CHNG 1. M U 1. I TNG V NHIM V CA VI SINH VT HC 1.1 i tng Xung quanh chng ta, ngoi cc sinh vt ln m chng ta c th nhn thy c, cn c v vn vi sinh vt nh b, mun nhn thy chng phi s dng knh hin vi, ngi ta gi chng l vi sinh vt. Mn khoa hc nghin cu v hot ng sng ca cc vi sinh vt c gi l Vi sinh vt hc. Vi sinh vt hc pht trin rt nhanh v dn n vic hnh thnh cc lnh vc khc nhau: vi khun hc (Bacteriology), nm hc (Mycology), to hc (Algology) virus hc (Virolory),... Vic phn chia cc lnh vc cn c th da vo phng hng ng dng. Do chng ta thy hin nay cn c y sinh vi sinh vt hc, vi sinh vt hc th y, vi sinh vt cng nghip, vi sinh vt hc nng nghip. Ngay trong vi sinh vt hc nng nghip cng c rt nhiu chuyn ngnh: vi sinh vt lng thc, vi sinh vt thc phm,... Mi lnh vc c i tng c th ring, cn i su. Tuy nhin mc nht nh cc chuyn ngnh trn u c nhng im c bn ging nhau. Vi sinh vt hc i cng, nghin cu nhng quy lut chung nht v vi sinh vt. i tng nghin cu ca vi sinh vt hc l vi khun, x khun (Actinomycetes), virus, Bacteriophage (th thc khun), nm, to, nguyn sinh ng vt. Vi khun: l nhm vi sinh vt c nhn nguyn thy, c th n bo, sinh sn ch yu bng hnh thc trc phn, c th nh b, mun quan st c phi s dng knh hin vi quang hc. Virus: l nhng sinh vt m kch thc ca chng v cng nh b, k sinh ni bo tuyt i, mun quan st chng phi s dng knh hin vi in t. Nm: trc y c coi l thc vt bc thp nhng khng c dip lc t, thng n bo, c nhm gi a bo, c th phn nhiu nhnh nhng khng c vch ngn hoc vch ngn nhng chnh gia c l thng, thuc t bo nhn tht. Vi sinh vt tuy c kch thc nh b v c cu trc c th tng i n gin nhng chng c tc sinh si ny n rt nhanh chng v hot ng trao i cht v cng mnh m. Vi sinh vt c th phn gii hu ht tt c cc loi cht c trn th gii, k c nhng cht rt kh phn gii, hoc nhng cht gy hi n nhm sinh vt khc. Bn cnh kh nng phn gii, vi sinh vt cn c kh nng tng hp nhiu hp cht hu c phc tp, trong iu kin nhit , p sut bnh thng. 1.2. S phn b ca vi sinh vt Vi sinh vt phn b rng ri trong t nhin: trong t, nc, khng kh,

trn c th cc sinh vt khc, trn lng thc, thc phm v cc loi hng ha. Chng nhng th, s phn b ca chng cn theo mt h sinh thi v cng phong ph, a dng, t lnh n nng, t chua n kim, t ho kh n k kh,... Do s phn b rng ri v do hot ng mnh m nn vi sinh vt c tc dng rt ln trong vic tham gia cc vng tun hon vt cht trn tri t cng nh tham gia vo cc qu trnh sn xut nng nghip. Vi sinh vt hc i cng, nghin cu nhng quy lut chung nht v vi sinh vt. 1.3. Nhim v ca vi sinh vt hc -Nghin cu cc c im c bn v hnh thi, cu to, di truyn, hot ng sinh l ha hc,ca cc nhm vi sinh vt. -S phn b ca vi sinh vt trong t nhin v mi quan h gia chng vi mi trng v cc sinh vt khc. -Nghin cu cc bin php thch hp c th s dng mt cch c hiu qu nht vi sinh vt c li cng nh cc bin php tch cc nhm ngn nga cc vi sinh vt c hi trong mi hot ng ca i sng con ngi. 2. LCH S PHT TRIN CA VI SINH VT HC Cn c vo qu trnh pht trin c th chia vi sinh vt hc ra lm 4 giai on pht trin. 2.1. Giai on trc khi pht minh ra knh hin vi T thi thng c ngi ta bit phn, trng xen cy h u vi cy trng khc, men, nu ru, nhng cha gii thch c bn cht ca cc bin php. Trong qu trnh nh canh con ngi thy c tc hi ca bnh cy. i vi bnh r st thi Aristote ngi ta xem nh l do to ha gy ra. Hy Lp by gi ngi ta cho rng cy b bnh l do t xu, phn xu, gy ra kh hu khng n ho nhng ch yu l do tri t. Trung Quc vo th k th nht trc cng nguyn trong quyn K thng Chi th ghi: mun cho cy tt phi dng phn tm, khng c phn tm th dng phn tm ln tp cng c. Trong sch ny cng ghi nhn trng xen cy h u vi cc loi cy trng khc. Trong cc ti liu Gip ct ca Trung Quc cch y 4000 nm thy cp n k thut nu ru. Ngi ta nhn thy trong qu trnh ln men ru c s tham gia ca mc vng, nh vy vi sinh vt c ng dng vo sn xut, phc v cuc sng t rt lu, nhng ngi ta cha hiu c bn cht ca vi sinh vt, mi n khi knh hin vi quang hc ra i, nhng hiu bit v vi sinh vt dn dn c pht trin, m ra trc mt nhn loi mt th gii mi, th gii ca nhng vi sinh vt v cng nh b nhng v cng phong ph. 2.2. Giai on sau khi pht minh ra knh hin vi (Pht hin ra vi sinh vt)

Leewenhoek l ngi u tin pht hin ra vi sinh vt nh pht minh ra knh hin vi, ng l mt thng nhn bun vi, mun tm hiu cu trc ca si vi ng ch to ra cc thu knh v lp rp chng thnh mt knh hin vi c phng i 160 ln, ng quan st nc ao t, nc ngm cc cht hu c, ba rng, Leewenhoek nhn thy u cng c nhng sinh vt nh b. Rt ngc nhin trc nhng hin tng quan st c ng vit Ti thy trong ba rng ca ming ca ti c rt nhiu sinh vt t hon hot ng, chng nhiu hn so vi vng quc H Lan hp nht. Pht minh ca Leewenhoek cng c quan nim v kh nng t hnh thnh ca vi sinh vt. Thi gian ny ngi ta cho rng sinh vt quan st c l t cc vt v sinh, tht, c sinh ra di v sau ngi ta cho ra i thuyt t sinh (hay thuyt ngu sinh). A- Knh hin vi u tin ca nhn loi B- Bnh c ngng m Pasteur nh hc thuyt t sinh 2.3. Giai on vi sinh vt hc thc nghim vi Pasteur n th k XIX cng vi s pht trin ca ch ngha t bn, cc ngnh khoa hc k thut ni chung v vi sinh vt hc ni ring, pht trin mnh m, nhiu nh khoa hc quan st v nghin cu v mt s vi sinh vt gy bnh v sng to ra mt s phng php mi nghin cu v vi sinh vt. ng gp cho s pht trin ca vi sinh vt giai on ny phi k n nh bc hc ngi Php Pasteur (1822-1895). Vi cng trnh nghin cu ca mnh ng nh hc thuyt t sinh, nh ch to ra bnh c ngng. ng chng minh thuyt t sinh l khng ng bng cc th nghim sau: TN1: Dng mt ci bnh cha nc tht un si, ngui sau mt thi gian th nc tht c, quan st thy c vi sinh vt. TN2: Tin hnh nh th nghim th nht nhng sau ng bt kn ming bnh li, mt thi gian nc tht khng b vn c. Lc ny mi ngi phn i, h ni khng c khng kh nn vi sinh vt khng pht trin c, cha thuyt phc c h ng lm th nghim tip theo. TN3: ng un c bnh ging nh hnh c ngng ko di ra cho thng vi khng kh, sau khi un si mt thi gian nc tht khng b c, khi ngi ta mi cng nhn bc b thuyt t sinh. Pasteur l ngi xut thuyt mm bnh, thuyt min dch hc, l c s sn xut vaccin trong phng bnh. ng chng minh bnh than cu l do vi khun gy ra v lan truyn t con bnh sang con lnh v ng tin hnh th nghim tim phng vaccin nhit thn cho cu nm 1881, ng chn 50 con cu khe mnh, tng ng, tim vaccin cho 25 con cn 25 con khng tim vaccin, sau cng c th 25 con khng tim vaccin

b cht cn 25 con tim vaccin sng bnh thng. Thi h b ch di cn l phi cht, rt thng tm trc ci cht ca nhng ngi b ch di cn, ng lao vo nghin cu vaccin phng v tr bnh ch di, thnh cng u tin l cu mt b trai thot khi pht bnh di. Sau khi thnh cng cc nh ho tm xy dng vin Pasteur ti php, sau ny nhn rng ra, y l thnh cng ln nht ca Pasteur i vi nhn loi. L. Pasteur tt nghip sinh ha, ng rt thnh cng trong nghin cu nhng gia nh ng rt bt hnh, anh trai v cc con ca ng u cht do bnh tt. Mc du L. Pasteur l ngi u tin chng minh c s khoa hc ca vic ch to vaccin nhng thut ng vaccin li do mt bc s nng thn ngi anh Edward Jenner (1749-1823) t ra. ng l ngi u tin ngh ra phng php chng u bng m u ma b cho ngi lnh, phng bnh u ma, mt cn bnh ht sc nguy him cho tnh mng thi by gi. 2.4. Giai on sau Pasteur v vi sinh hc hin i Tip theo sau Pasteur l Koch (Robert Koch 1843-1910), l ngi c cng trong vic pht trin cc phng php nghin cu vi sinh vt. ng ra phng php chng minh mt vi sinh vt l nguyn nhn gy ra bnh truyn nhim m ngy nay mi nh nghin cu bnh hc phi theo v gi l quy tc Koch. Ngy 24-3-1882, Koch cng b cng trnh khm ph ra vi trng gy bnh lao v gi n l Mycobacterium tuberculosis, l mt bnh nan y thi . Khm ph ny m ng cho vic cha tr bnh ngy nay. K hc tr ca Koch l Petri (Juliyes Richard Petri, 1852-1921) ch ra cc dng c nghin cu vi sinh vt m ngy nay cn dng tn ca ng t cho dng c y: a Petri. ng cng nu ra cc bin php nhum mu vi sinh vt. Ivanopxki, 1892 v Beijerrinck, 1896 l nhng ngi pht hin ra virus u tin trn th gii khi chng minh vi sinh vt nh hn vi khun, qua c lc bng s xp, l nguyn nhn gy bnh khm cy thuc l. Ngy nay vi sinh vt pht trin rt su vi hng trm nh bc hc c tn tui v hng chc ngn ngi tham gia nghin cu, cc nghin cu i su vo bn cht ca s sng mc phn t v di phn t, i su vo k thut cy m v tho lp gen vi sinh vt v ng dng k thut tho lp ny cha bnh cho ngi, gia sc, cy trng v ang i su vo gii quyt bnh ung th loi ngi Hooke (1665) ln u tin quan sat thy t bao Anton van Leewenhoek (1632-1723)

Louis Pasteur (1822-1895) Robert Koch (1843-1910) Alexander Fleming (1881-1955) Watson and Crick (1953) phat hin ra cu truc cua DNA Klug (1982) phat hin ra cu truc virus kham thuc la (TMV) 3. VAI TR CA VI SINH VT TRONG HOT NG SNG CA CON NGI V TRONG NNG NGHIP Trong thin nhin, vi sinh vt gi nhng mt xch trng yu trong s chu chuyn lin tc v bt dit ca vt cht, nu khng c vi sinh vt hay v mt l do no m hot ng ca vi sinh vt b ngng tr d ch trong thi gian ngn, c th n s lm ngng mi hot ng sng trn tri t. Tht vy ngi ta tnh ton nu khng c vi sinh vt hot ng cung cp CO2 cho kh quyn th n mt lc no lng CO2 s b cn kit, lc by gi cy xanh khng th quang hp c, s sng ca cc loi sinh vt khc khng tin hnh bnh thng c, b mt tri t s tr nn lnh lo. Vi sinh vt cn l nhn t tham gia vo vic gi gn tnh bn vng ca cc h sinh thi trong t nhin. i vi sn xut nng nghip, vi sinh vt c vai tr rt ln, vi sinh vt tham gia vo vic phn gii cc hp cht hu c, chuyn ha cc cht khong, c nh nit phn t lm giu thm d tr nit ca t. Trong qu trnh sng, vi sinh vt cn sn sinh ra rt nhiu cht c hot tnh sinh hc cao c tc dng trc tip i vi qu trnh sinh trng, pht trin ca cy trng, vt nui. Ngi ta nhn thy nu khng c vi sinh vt tiu th cc sn phm trao i cht do cy trng tit ra quanh b r th mt s sn phm ny s u c tr li cy trng. Trong chn nui v ng nghip, vi sinh vt cng c tc dng rt to ln, trong c th ca cc loi ng vt u c mt h vi sinh vt rt phong ph, h vi sinh vt ny gip cho qu trnh ng ha cc cht dinh dng v thi cc cht cn b trong qu trnh sng. Trong chn nui mt vn ln l lm th no phng chng c cc bnh truyn nhim, mn vi sinh vt th y cng mn dch t hc ra nhng bin php phng dch bnh ca sc vt v mt s bnh c th ly sang ngi, nh di, lao, nhit thn,... Hin nay vi sinh vt l mt mn khoa hc mi nhn trong cuc cch mng sinh hc. Nhiu vn quan trng ca sinh hc hin i nh, ngun gc s sng, c ch thng tin, c ch di truyn, c ch iu khin hc v cc t chc sinh vt hc, vi sinh vt hc ang c nhng bc tin v i, ang tr thnh v kh sc bn trong tay con ngi nhm chinh phc thin nhin phc v c lc cho sn xut v i sng.

MC TIU: Sau khi phn hc xong phn na sinh vin nm c: 1. S pht trin cu ngnh virut hc v tm quan trong cu n. 2. Virut l nhm i tng c bit cu ngnh virut hc. 3. Cc c im cu virut. 4. Cu ta cu virut. 5. Cc kiu chu trnh sng cu cc virut vi khun v ng, thc vt.

Chng 2: VIRUS

6. Virut v bnh tt. I/ LC S PHT HIN V NGHIN CU VIRUT. I.1 Pht hin ra virut l tc nhn gy nhiu b nh cc lo i c th sng. Trc khi loi ngi bit n bn cht cu virut, n l tc nhn gy nhiu bnh truyn nhim. ngi ta tm thy du du v t gy b nh virut trn ngi t thi thng c. nm 1884, Lui Paster khi nghin cu bnh da gi nh rng tc nhn gy bng da l mt loi t ba sng nh hn vi khun v ng ngh s dng thut ng virut dnh cho loi bnh khng r ngun gc( virut _ tin lalinh c nghi l cht c). _Nm 1892, . I. Ivannpxkii d chng minh rng dch qua lc t cy thuc l b bnh m thuc l c bn cht sng, c kh nng ly nhim v rt ra kt lun: tc nhn gy bnh m thuc l l mt loi vi sinh vt i qua ht tha cc loi phu lc vi khun. _Nm 1898, Beijerinck Martinus khng nh kt lun cu ivanopxkii v tnh k sinh bt buc cu chng: nguyn nhn gy bnh m thuc l l do dch cht c sng qua lc. Cht dch c ny ch gy b nh tr6en m sng cu cy thuc l, c th mt hot tnh khi dun si, nhng nu s y kh s vn bo ton hot tnh. Cc vi sinh vt qua l c ny nga nay c gi chung l vi rut. _Tip , cc loi virut gy bnh trn ngi, ng vt v vi sinh vt cng ln luc c khm ph, v d virut gy bnh l mm lng mng i gia sc c sng, virut gy bng s vng chu phi, virut gy bnh mu trng g, virut gy khi u g. Nm 1915,F.W.Twort d quan st tht hin tng virut ln tan Micrococcus trn mi trng thch. Nm 1917 Fellix D Herelle phn lp c virut lm tan Shigella disenteriae. ng gi virut k sinh trn vi khun l thc khun. _Ngy nay danh sch cc virut gy bnh ngi v ng thc vt nga cng di thm, trong c hhiu loi virut gy bnh cc ki nguy him nh HIV/AIDS, virut Ebola, virut Sart v cm g tuyp A(H5n1), virut ung th gan, vng hng, Burkit. I.2 Nghin cu v hnh thi, cu to ht virut v xy d ng cc phng php nghin cu virut. Ngnh virut hc cng tin nhng bc tin rt di v xy d ng phng php nghin cu ton din v bn cht virut. + Nm 1933 bng phng php li tm c bit, Schllesinger thu c Phage dng thun chng. +Nm 1940 nh c s ra i cu knh hin vi in t, ngi ta nhn thy virut m thuc l( Tabaco mosaic virut= TMV) v ngnh virut h c c nhng bc pht trin nhanh chng.

+Nm 1935 Stanley tinh th ha uc TMV. + Nm 1937 Bawden v Pirie thun chng TMV v xc inh c thnh phn cu trc cu ht TMV gm c axit nuclic (ARN) v v protein. + Mt d TMV l virut uc pht hin sm nht nhng cc th nghi m sinh ho v di truyn v sau ny li ch yu uc tin hnh trn phage. + Holmos (1929) x nh phng php m n v nhim thc vt nh cc vt hoi t trn cy v l. +Max Theiler (1937) a ra phng php nui cy virut ng vt trong phi g m u s nghi cu cc virut ng vt. S nui cy thnh cng cc virut trn cc m sng nhn to cu Ender nm 1949 cho php cc nghin cu virut tin hnh thun li hn. Tip , nm 1952 Dulbelco a ra phng php m n v nhim ng vt nh nui cy t bo mt lp trong hp petri. +Nm 1941 Hirst pht hin kh nng lm ngng kt hng cu cu virut cm t nn mng cho phng php chun an cc bnh virut bng huyt thanh v min dch hc virut. +T nhng nm 1960 cc phung php huyt thanh v mi n d ch h c ti p tc c pht trin v hon thin. + Nm 1975 nh thnh cng cu Kohler v Mils v to khng th n dng m ra mt bc tin mi trong vic hon thin cc phung php nghin cu virut. II. A CNG V VIRUT II.1 Tm tt v c im chnh (tnh cht) cu virut: -Virut l mt nhnh cu s sng, bao gn nhng th sng siu hin vi, nm ranh gii gia phn t hu c ln nht( phn t albumin 10 nm) v t bo vi khun nh nht ( Mycoplasma _ 150nm) i qua mng lc vi khun khng nhn thy di knh hin vi quang hc, khng lng ng trong my quay li tm thng. -Virut ch c kt cu a phn t, khng c cu to t bo, thng c gi l ht virut ch khng go l t bo virut( virut particles). Thnh ph n cu ht virut ch bao gm v protein v li axit nucleic ( mt vi virut phc tp c mng bao bc cha thm polisaccharit hoc lipopolisaccharic) -Khng c h thng trao i cht v nng lng ring. Khc vi tt c cc loi vi sinh vt bit, ht virut ch cha mt loi axit nucleic ho c ADN hoc ARN. Ch c axit nucleic mi gi chc nng di truy n, protein v v bc ch gi chc nng nng bo v. -Virut l vi sinh vt k sinh bt buc, ch sinh trng pht tri n trong t bo vt ch sng. Khi ngoi c th vt ch vi rut ch c th tn ti dng i phn t ho hc v c tnh truyn nhim ( dng virion).

-Mt s virut thc vt c kh nng hnh thnh tinh th. Virut l nhm c bit cu sinh gii v c kh nng gy bnh trn tt c cc sinh vt khc t vi khun , nm to nguyn sinh ng vt n th c vt v con ngi,. - V nhng tnh cht rt c bit nh trn virut cha c xp vo bt c nhm phn loi na trong cc h thng phn loi sinh gii. II.2 Nhng c im c trng cu virut II.2.1 Hnh dng, kch thc - Virut cha c cu to t bo, mi virut khng th gi l mt t bo m c go l ht virut hay virion. l mt virut thnh th c c c u trc hon chnh. Virut c nhiu dng hnh thi khc nhau. 1. hnh dng cu i xng xon Dng thng hay gp, a s cc virut gy bnh cho ngi v ng vt thng dng ny nh virut cm, virut quai b, virut ung th ngi v gia cm, kch thc t 100- 150 nm.

Virut quai b

virut ung th

2. Dng hnh que i xng xon Gm hu ht cc virut gy bnh cho thc vt nh: virut m l cy thuc l, virut m khoai ty, kch thc t 15-250 nm. 3. Dng hnh khi i xng xon Cy m thuc l Gm cc virut c nhiu gc cnh, c cu to phc tp nh: virut u mu, virut khi u cu ngui v ng vt, virut ng h hp, kch thc t 30-300nm. 4. Dng hnh tinh trng Gm hai phn: phn u c dng hnh khi sa cnh, ph n sau l ui c Virut u ma dng hnh que, go l thc khun th (phage, bacteriophage) c kch th c bin ng t 10-250nm.

Tr virut u ma c th quan st bng knh hin vi quang hc, cn h u ht tt c cc virut c kch thc khong 1,2 m th khng th y c. V ln th virut h Poxviridae c kch thc ln nht 250 nm v virut nh nht l virut thuc h Piconaviridae c kich thc khong 10- 20 nm. II.2.2 C TRC CU VIRUT C th khi qut cu trc ca viut nh sau: V V capsit Mng bc + gai+enzim( mt s virut) Li AND hoc ARN

Ht virut

enzym( mt s virut) Tt c cc virus u c cu to gm hai thnh phn c bn: li l acid nucleic (tc genom) v v l protein gi l capsid, bao bc bn ngoi bo v acid nucleic. Phc hp bao gm acid nucleic v v capsid gi l nucleocapsid hay xt v thnh phn ho hc th gi l nucleoprotein. i vi virus ARN th cn gi l ribonucleoprotein Genom ca virus c th l ADN hoc ARN, chui n hoc chui kp, trong khi genom ca t bo lun l ADN chui kp, v trong t bo lun cha hai loi acid nucleic, ADN v ARN. II.2.2.1V capsid: - Capsid l v protein c cu to bi cc n v hnh thi gi l capsome. - - Capsome li c cu to t 5 hoc 6 n v c u trc g i l protome. Protome c th l monome (ch c mt phn t protein) hoc polyme (c nhiu phn t protein) - Pentame (penton) c 5 protome nm trn cc nh ca khi a din, cn hexame (hexon) to thnh cc cnh v b mt hnh tam gic. - Capsid c kh nng chu nhit, pH v cc yu t ngoi cnh nn c ch c nng bo v li acid nucleic - Trn mt capsid cha cc th th c hiu, hay l cc gai glicoprotein, gip cho virus bm vo cc th th trn b mt t bo. y cng chnh l cc khng nguyn (KN) kch thch c th to p ng min dch (MD). V capsid c kch thc v cch sp xp khc nhau khin cho virus c hnh dng khc nhau. C th chia ra ba loi cu trc: i xng xon, i xng hnh khi v cu trc phc tp (Hnh 1).

Hnh 1. Kch thc v hnh thi ca mt s virus in hnh .Theo Presscott L. M. et al. , Microbiology. 6th ed. Intern. Ed. 2005.

1. Cu trc i xng xon:

S d cc virus c cu trc ny l do capsome sp xp theo chiu xon ca acid nucleic. Tu loi m c chiu di, ng knh v chu k lp li ca cc nucleocapsid khc nhau. Cu trc xon thng lm cho virus c dng hnh que hay hnh si v d virus m thuc l (MTV), di (rhabdo), quai b, si (paramyxo), cm (orthomyxo). virus cm cc nucleocapsid c bao bi v ngoi nn khi quan st di knh hin virus in t thy chng c dng cu. ( chen hinh) 2. Cu trc i xng dng khi a din 20 mt

Hnh ca phng th nghim cc virus loi ny, capsome sp xp to v capsid hnh kh i a di n vi 20 mt tam gic u, c 30 cnh v 12 nh. nh l n i g p nhau c a 5 cnh thuc loi ny gm cc virus adeno, reo, herpes v picorna. Gi l i xng v khi so snh s sp xp ca capsome theo trc. V d i xng bc 2, bc 3, bc 5, v khi ta xoay vi 1 gc 1800 (b c 2), 1200 (b c 3) v 720 (bc 5) th thy vn nh c. Cc virus khc nhau c s lng capsome khc nhau. Virus cng ln, s lng capsome cng nhiu. Da vo s lng capsome trn mi cnh c th tnh c tng s capsome ca v capsid theo cng thc sau: N= 10(n-1)2+2 Trong N- tng s capsome ca v capsid, n-s capsome trn mi cnh.

Hnh 2. A. S virus hnh que vi cu trc i xng xon (virus khm thuc l). Capsome sp xp theo chiu xon ca acid nucleic. B- S virus a din n gin nht. Mi mt l mt tam gic u. nh do 5 cnh hp li. Mi cnh cha 3 capsome. C- S i xng ca hnh a din th hin khi quay theo trc bc 2 (1800), bc 3 (1200) v bc 5 (720). Theo J. Nicklin et al., Instant Notes in Microbiology, Bios Scientific Publisher, 1999 i din kiu cu trc khi c cc loi: virut ng h hp,virut ng rut, virut khi u. 3. Virus c cu to phc tp Mt s virus c cu to phc tp, in hnh l phage v virus u ma. Phage c cu to gm u hnh khi a din, gn vi ui c cu t o i xng xon. Phage T chn (T2, T4, T6) c ui di trng gi ng nh tinh trng, cn phage T l (T3,T7) c ui ngn, th m ch c lo i khng c ui Virus u ma c kch thc rt ln, hnh vin gch. gia l li lm hai pha trng nh qu t. i din vi hai mt lm l hai cu trc d ng th u knh gi l th bn. Bao bc li v hai th bn l v ngoi. II.2.2.2. Axit nucleic Nm gia ht virut to thnh li hay h gen ca virut, ch a axit nucleic, mi loi virut u c mt trong hai axit nucleic hoc AND ho c ARN. Nhng virut c cu trc AND phn ln mang AND si lp, cn virut mang ARN th ch yu dng si n. Axit nucleic ch y u l vt li u c m ho mang thong tin di truyn ca virut, hu ht cc virut th c v t ch a

ARn, virut gy bnh cho ngi v ng vt mt s ch a AND, mt s cha ARN, cn thc th khun(phage) th lun lun cha AND. Trong dng virut que, axit nucleic xp xp nh mt mch xon vng, ging nh hnh l xo xon c. Trong dng virut hnh khi, hnh cu v phn u ca phage th axit nuleic nm cun trn chnh gia trong nh cun len ri. Axit nuleic ca virut ch chim t 1-2% khi lng ca ht virut,nh ng c chc nng c bit quan trng: + cc axit nuleic mang mt m di truyn t trng cho tng virut. + axit nuleic quyt nh kh nng gy nhim trng ca virut trong tng t bo cm th. + axit nuleic quyt nh chu ki nhn ln ca virut trong tng t bo cm th. + axit nuleic mang tnh bn khng nguyn trong tng t bo cm th. II.2.2.3 Cu trc ring 1.Cu trc bc ngoi hay v bc ngoi(envelop) Mt s virut bn ngoi capsit cn c mt mng bao, gi l envelop, cu to bi lipoprotein, trn mng bao cn c th c them gai nh (spike) bm xung quan. Mng ny thc cht l mng t bo cht ca vt ch nhng b virut ci to thnh v mang tnh khng nguyn t trng cho virut, mng bao c th b cc dung mi ha tan virut ph hy. Cu trc v ngoi ca virut c mt s chc nng sau: + Tham gia vo s ca virut trn cc v tr thch hp ca t bo cm th, nh cht hemagglutinin ca virut cm. + Tham gia vo giai on lp rp v gii phng virut ra khi t bo. + V bc ngoi gip cho virut gi c tnh n nh ca kch thc. +To nn cc khng nguyn cc hiu trn b mt virut. 2. Enzym Trong thnh phn cu trc ca virut c mt s enzyme, l nh ng enzyme cu trc, chng gn vi cu trc ca h t virut hon ch nh. Cc enzyme cu trc thng gp l Neuraminidaza, AND v ARN polimeraza, men sao chp ngc(reverse transcriptase). Mi enzyme cu trc c nhng chc nng ring trong chu k nhn ln c a virut trong t bo cm th v chng cng mang tnh khng nguyn ring t hiu cho mi loi virut. 3.Tiu th bao hm(inclusion) Trong t bo ng vt v thc vt b nhin vi rut, c th xut hin nh ng ht nh trong nhn hoc trong t bo tng, c kch thc v bt mu c trng nn c th nhum v quan st di knh hin vi quang hc c,

ng thi da vo c th d on gin tip s nhim virut trong t bo.Bn cht ca cc ht ny c th l do cc ht virut ko6ng gi i phng khi t bo hoc c th l do thnh phn cu trc ca virut ch a c lp rp thnh ht virut mi, cng c th l cc ht phn ng ca t bo khi nhin virut, nhng ht gi l tiu th bao hm hay th n nhp(inclusion). V d trong nguyn sinh cht t bo ca ngi mt u ma c tiu th bao hm Guarnieri, g mt bnh u c tiu th bao hm Bollinge, trong nguyn sinh cht t bo thn kinh trung ng ca ngi mt bnh di c tiu th bao hm Negri. III Chu trnh nhn ln ca virut trong t bo vt ch _Virus khng c kh nng sng c lp, chng sng k sinh trong t bo sng. Kt qu ca qu trnh k sinh c th xy ra 2 kh nng: Kh nng th nht l ph v t bo lm t bo cht v tip tc xm nhp ri ph v cc t bo ln cn. Kh nng th 2 l to thnh trng thi tim tan trong t bo ch, ngha l tm thi khng ph v t bo m ch hot ng sinh sn cng nhp iu vi t bo ch. nhng iu kin mi trng nht nh, trng thi tim tan c th bin thnh trng thi tan ph v t bo. _Nhng virus c kh nng ph v t bo gi virus c, nh ng virus c kh nng to nn trng thi tim tan gi l virus khng c. Qu trnh hot ng ca virus c: Qu trnh ca virus c chia lm 4 giai on: + Giai on 1: Giai on hp th ca ht virus t do trn t bo ch: Cc ht virus t do tn ti ngoi t bo khng c kh nng hot ng, chng trng thi tim sinh gi l ht Virion. Khi gp t bo ch , ph thuc vo tn s va chm gia ht virion v t bo, va chm cng nhiu cng c kh nng tm ra cc im th cm trn b mt t bo gi l cc receptor. Lc im th cm ca t bo ch v gc ui ca virus kt hp vi nhau theo c ch khng nguyn - khng th nh c thnh ph n ho hc ph hp vi nhau. Kt qu l virus bm cht ln b mt t bo ch. Mi loi virus c kh nng hp th ln mt hoc vi lo i t bo nht nh. iu ny gii thch c ti sao mi loi virus ch gy bnh cho mt vi loi nht nh. + Giai on 2:Giai on xm nhp ca virus vo t bo ch Qu trnh xm nhp ca virus vo t bo ch xy ra theo nhiu c ch khc nhau ph thuc vo tng loi virus v t bo ch .

thc khun th T4 sau khi virus bm vo im th cm ca t bo ch, n tit ra men Lizozym thu phn thnh t bo vi khun. Sau di tc dng ca ATP - aza bao ui ca phage co rt lm cho tr ui xuyn qua thnh t bo v phn t ADN c bm vo bn trong t bo ch . V capxit vn nm ngoi. Ngi ta chng minh c c ch trn nh phng php nguyn t nh du. Ngoi c ch trn cn c mt s c ch khc: mt s virus ng vt, sau khi tit ra men phn hu thnh t bo ch, ton b ht virion lt vo trong t bo, sau cc men bn trong t bo mi tin hnh phn hu v Capxit gii phng ADN. Ngi ta gi l qu trnh ny l qu trnh ci o. Mt s t bo ch li c kh nng bao bc virion ri nut theo ki u thc bo. Sau c qu trnh ci o gii phng ADN ca virus. + Giai on 3: Giai on sinh sn ca virus trong t bo ch (sao chp v nhn ln). Qu trnh sinh sn ca virus cn gi l s nhn ln c a chng. y l v n rt hp dn ca sinh hc phn t trong thi gian gn y. Bng cc phng php hin i ngi ta lm sng t qu trnh nhn ln ca virus. Sau khi phn t ADN ca virus lt vo t bo ch, qu trnh t ng hp ADN ca t bo ch lp tc b nh ch. Sau qu trnh tng h p protein ca t bo cng ngng v bt u qu trnh tng hp cc enzym ny cn gi l protein sm v n l nhng protein c tng hp u tin sau qu trnh xm nhp. Khi cc enzym ny c hon thnh, b t u xc tc cho qu trnh tng hp ADN ca virus bng nguyn liu ADN ca t bo ch b phn hu. Sau khi cc phn t ADN virus c tng hp n mt s lng nht nh qu trnh ny ngng v bt u qu trnh tng hp Protein mun bao gm v Capxit ca virus v cc enzym c trong thnh phn ca virus trng thnh. Cc qu trnh ny c tin hnh do s i u khin ca b gen virus. Nh vy, 2 phn v v li virus c tng h p ring bit. + Giai on 4: Giai on lp rp ht virus v gii phng chng ra khi t bo: Giai on ny cn gi l s chn ca virus. Sau khi cc b ph n c a virus c tng hp ring bit (axit nucleic, v capxit, bao ui, a gc, lng ui) cc thnh phn lp rp li vi nhau thnh ht virus trng thnh, kt thc thi k tim n, tc l thi k trong t bo cha xut hin virus trng thnh. Thi k tim n ko di bao lu tu thuc tng loi virus. Trong nhiu trng hp cc virus trng thnh tit men lizozym phn hu thnh t bo v ra ngoi, t bo b ph v. Cc virus con tip tc xm nhp vo cc t bo xung quang v ph v chng. mt s virus, virus tr ng thnh khng ph v t bo m chui ra qua l lin bo sang t bo bn c nh

hoc c phng thch nh qu trnh o thi ca t bo. Trong t bo u tin vn tip tc qu trnh tng hp virus mi. c 2 c ch , t bo ch sm mun cng b cht hng lot. l qu trnh hot ng ca virus c. Sau y ta nghin cu qu trnh hot ng ca virus khng c. Qu trnh hot ng ca virus khng c Virus khng c cn gi l virus n ho, hot ng ca n khng lm ch t t bo ch m ch gy nn trng thi tim tan, gi l trng thi Lyzogen. Virus sng chung vi t bo ch, sinh sn cng nhp iu vi n. Hin tng Lyzogen c pht hin trn vi khun, cc phage ny c gi l phage n ho hoc prophage. T bo c cha prophage c kh nng min dch vi cc phage khc. Nguyn nhn ca hin tng ny l do prophage c kh nng tng hp nn cc protein c tc dng km hm s nhn ln ca virus l cng nh vn thn prophage. Mt s tc nhn t bin lm mt hot tnh hoc lm ngng s tng hp cht km hm trn, dn n s thay i trng thi Lyzogen, tc l bin trng thi ti m tan thnh trng thi tan. Lc phage n ho bin thnh phage c v t bo ch s b ph v. Qu trnh ny ngoi tc nhn t bin cn ph thuc vo h gen ca prophage v trng thi sinh l ca t bo cng nh c im nui cy. Bi vy, cng mt loi vi khun, c nh ng ch ng c m ng v i phage, c chng khng. Khi nui chung hai chng vi nhau trn mi trng thch a c th thy r nhng vt b tan trong thm vi khun khng b tan. Trong iu kin t nhin, tn s bin trng thi ti m tan thnh trng thi tan ch l 10-2 10-5. Chu trnh nhn ln ca virut trong t bo bao gm 5 giai on. Cc giai on: Cc c im giai on 1 Hp th _ Virut bm trn b mt vt ch nh th th t hiu vi th th ca t bo vt ch. _ Virut bm mt cch t hiu ln th th b mt t bo nh gai glycoprotein t hiu vi th th trn b mt t bao. _ Chnh v s bm t hiu trn m i loi virut ch c th k siinh trn mt hoc mt s loi vt ch nht nh 2 Xm _ Bao ui ca virut co li y b gen ca virut chui vo nhp trong t bo vt ch.

3 4 5

Sinh tng hp Lp rp Phng thch

_virut ng vt a c nulecapsit vo t bo cht sau ci v gii phng axit nuleic. _Vrut tit enzyme lizoxom ph hu thnh t bo a axit nuleic vo trong _ B gen ca virut iu khin b my di truyn ca t bo ch tng hp AND v v capsit cho mnh. _ V capsit bao ly li AND, cc b phn nh a gc, ui gn li vi nhau to thnh virut hon chnh.. _ Cc virut mi c tho thnh ph b v t bo ch at ra ngoi to thnh mt l thng trn v t bo ch v chui ra ngoi. _ Khi virut nhn ln m lm tan t both gi l chu trnh tan.

S ho nm giai on pht trin ca phage c: IV. Hin tng cm nhim (Interference) v ng dng ca n Interference l hin tng khi gy nhim mt loi virus cho t bo th vic gy nhim virus khc s b c ch. Hin tng c ch ny khng c tnh c hiu i vi virus. Cc virus hon ton khc nhau c th c ch nhau, v d virus AND c th c ch s xm nhim ca virus ARN v ngc li. Mt virus b lm bt hoi bi tia cc tm vn c kh nng gy ra hin tng Interference i vi virus sng. Song hin tng ny li c tnh c hiu i vi loi thuc t bo ch. Cht c ch gi l Interferon sinh ra bi t bo thuc loi no th ch c tc dng i vi cc t bo thuc loi y. V d Interferon sinh ra t bo g th khng c tc dng c ch t bo b hoc ln. Interferon l mt loi protein c bit c sinh ra trong t bo sau khi b nhim virus. Chnh n c ch qu trnh tng hp ARN c a virus l, t khng th c qu trnh tng h p AND hay protein. B i v y m virus l c th xm nhp vo t bo nhng khng pht trin nhn ln

c. Cng ca hin tng ny ph thuc vo s lng virus gy nhim ln th 1 v thi gian t lc n lc gy nhim ln th 2, thng khong 2 gi th c tc dng. Ngi ta ng dng hin tng Interference trong vi c phng chng bnh do virus gy nn. Cht Interferon c th c ch rng ri nhiu loi virus khc nhau v n khng c tnh c hiu i vi virus m ch c tnh c hiu i vi t bo ch. V. Virut v bnh tt Virut l dng sng v bo gy nhiu loi bnh trn mi i tng sinh vt( t vi sinh cho n cc ng vt bc cao cp) l tc nhn gy h n 500 loi bnh trn c th ngi, ng vt v hn 600 bnh hin bi t trn thc vt. T nm 1971, ngi ta cn lien tip pht hin ra cc tc nhn gy bnh c cu trc n gin hn c virut: chnh l viriot (virino), prion) v virutoit. Ngy nay khi cc bnh dch virut c y li, th cc b nh virut khc li ang l nguy c e do tnh mng ca ton nhn loi:v d virut ebola gy bnh st xut huyt c tnh chu phi, virut gy b nh vim phi cp( SARS),, virut cm gia cm cc tnh(H5N1), virut B gy vim gan, virut gy ung th v virut HIV gy i AIDS. V.1 S lan truyn virut Bnh virut c th lan truyn theo hai c ch chnh: +S lan truyn dc( lan truyn di truyn): cc t bo b m nhim virut dng tin sinh truyn cho con chu t th h ny sang th h khc. V d cc virut thuc retro, virut gy AIDS, virut rubella.(Togaviridae) +Lan truyn ngang ) lan truyn tip xc: bao gm mt s con ng chnh sau: - Qua ng h hp: qua khng kh bn chc virut gy bnh, v d nh viirut cm, quai bi, si, u ma. - Qua ng tiu ho( qua thc n v nc ung b nhim) ,v d nh virut bi lit(poliomyelite),virut vim gan A( piconaviridae) - Qua ng sinh duc v tit niu:HIV, HIV - Lan truyn do vt trung gin nh mui, b cht, ch y r n.v d cc virut gy bnh st vng da, vim no, st vt, st xut huyt - Lan truyn qua vt cn; virut di(Rhabdoviridae) - Lan truyn ng truyn mu: HIV ,HBVVirus bnh di

V.2. Virut v bnh ung th Ung th l cn bnh nang y nht hin nay. Ngi ta bi t rng nguyn nhn ch yu gy bnh ung th l do thc n v mi trng sng( 30%60% ). Virut ch l nguyn nhn ca mt phn nh cc khi u c tnh( chim khong 5%). Cho n nay ngi ta cho rng c t nh t 4 lo i virut c lien quan cht ch n s tin trin ca ung th. l: +Virut Epstein (EBV) l virut gy bnh ung th c nghin cu l nh t. chng gy bnh mu trng (ung th mu dng burkit),ung th vm hng, ung th vng bng,ung th hm +Virut gy vim gan B(HBV) cng c chng minh ch c ch n lien quan n ung th gan. +Virut Papilona gy ung th c t cung ngi +t nht c mt loi retro virut gy bnh ung th t bo limpho ngi V.3.Virit HIV v hi chng suy gim min dch V.3.1 s lc v HIVVirus vim gan B

HIV (ting Anh: human immunodeficiency virus, c ngha virus suy gim min dch ngi) l mt lentivirus (thuc h retrovirus) c kh nng gy hi chng suy gim min dch mc phi (AIDS), mt hi chng h min dch trong c th con ngi bt u b hng, dn n nhng nhim trng c hi c th lm cht ngi.

Retrovirus l mt h virus ph bin cc loi ng vt v t ph bin hn ngi. H virus ny c dng hnh cu, bn ngoi c v lp pepton v bn trong c v capsid, di truyn ARN. V vy dng di truyn ca n l dng di truyn ngc chiu t ARN sang ADN ch khng phi thun chiu ADN sang ARN. ARN ca virus c phn m thnh ADN nh mt enzim c bit l mt enzim phin m ngc. ADN ca virus di truyn vo trong nhn v lng ghp vi ADN ca t bo b nhim tr thnh ADN tin virus, tn t i mt cch thm lng. Khi t bo b nhim phn chia, ADN ti n virus cng c chuyn cho t bo con. ADN tin virus c th sn sinh ra cc protein virus, tng hp cc proten v hnh thnh cc virus mi. Cc virus mi ny ph hu cc t bo m v gy nhim HIV cho cc t bo ln cn v c th tip tc nhn ln.

V.3.2Cu trc HIV: Bao ngoi l mt lp mng lipid kp, di mng c gai l cc glycoprotein trng lng phn t 120 kiloanton (KD) k hiu l gp120 hay cn gi l Protein mng ngoi. Xuyn qua cc lp lipid kp l cc lp glycoprotein gp41 (Protein xuyn mng) gp120 v gp41 gn vi nhau to thnh cc phn t gp160. V Protein: c dng hnh cu gm cc phn t Protein c trng l ng phn t 18KD, p18. Li: c dng hnh tr c bao bc bng mt lp protein p24. Trong li c hai si ARN n, c enzym phin m ngc v mt s phn t protein phn t lng nh. Trong mi si ARN ca Virus ny c 3 gen cu trc l gen GAG- gen m ho cho cc protein trong ca Virus; gen pol m ho cho cc enzyme phin m ngc v gen env m ho cho protein bao ngoi ca Virus gp120.

Cu to ca virus V.3.3 Cc biu hin lm ca nhim trng HIV c chia theo 4 giai on: sng

1. Nhim trng cp (cn gi l s nhim hay ni cch khc l th i k c a s) Trong 2-8 tun sau khi nhim HIV, bt k qua con ng no, 20% b nh nhn c biu hin ca mt nhim trng cp vi st (38-40 C), au c , au khp, v m hi, mt mi, chn n, nn i, tiu ch y, vim h ng, pht ban ngoi da (xut hin 50% bnh nhn), hch to, lch to. Mt s bnh nhn c biu hin thn kinh nh vim no, vim mng no, vim dy thn kinh ngoi bin Cc triu chng ny hin din trong vng 5-10 ngy v t khi hon ton. Cn li, hu ht nhng ngi nhim HIV khng c biu hin g khi mi nhim. Trong giai on ny, ch mi c s hin din ca khng nguyn tc virus HIV trong mu. Phi ch 2-12 tun sau khng th mi xut hi n v lc ny mi c th xc nh c bng cc th nghim xc nh nhim HIV thng thng (huyt thanh chn on). y l giai on c bit d ly do bnh nhn khng bit mnh nhim bnh. 2. Nhim trng khng triu chng Sau thi k nhim trng cp, bnh nhn nhim HIV ri vo giai o n di khng triu chng lm sng, nhng chn on huyt thanh li kh d dng, da vo s hin din ca khng th chng HIV. Tc l trong giai on ny bnh nhn s c kt qu chnh xc sau khi lm xt nghi m mu tm khng th chng virus HIV. S d, chng ta phi lm xt nghi m tm khng th l v vic xt nghim tm khng nguyn (pht hin virus HIV) i hi phi c iu kin c s vt cht v trang thit b cao cp.

Trong khi , tnh trng ngn sch ca chng ta th cha th p ng c. 3. Hi chng hch to ton thn v ko di Sau khi huyt thanh dng tnh, 50-70% trng h p xut hi n h i ch ng hch to ton thn v ko di. Hi chng ny c chn on khi c cc iu kin sau: - C t nht 2 hch khc nhau (khng k hch bn). - Mi hch thng c ng knh trn 1 cm. - Hin din ko di trn 1 thng -Khng gii thch c l do ni hch. Hay gp nht l hch c, ri n hch di hm, hch nch. Mt s hch t gp hn l hch khuu tay, trung tht (trong lng ngc), v trong bng. 4. Biu hin lm sng thc s ca AIDS Khi bnh nhn c chn on l AIDS ngha l m c cc b nh nhi m trng c hi t bn ngoi hay ni cch khc l do HIV n giai o n cui cng. Thi gian t lc bnh nhn c xc nh l AIDS n lc cht thng khng qu 2 nm, trung bnh l 18 thng. Ring i vi tr em, thi gian ny thng ngn hn, khong 10-12 thng. Biu hin lm sng chnh thng l nhim trng c hi hoc ung th. Phn ln l bnh nhn mc cc bnh lao c bit l lao phi, cc bnh ng tiu ho, bnh lin quan n dy thn kinh v cc nhim trng ngoi da. Tuy nhin, nu c chm sc tt, ngi bnh c th sng hon ton kho mnh trong vng 15-17 nm k t khi nhim HIV n khi c biu hin ca AIDS. Ngy nay, v i cc tin b trong thuc iu tr, thi gian ny cn kh quan h n nhi u. Tuy nhin, th thch ln nht hin ti l thuc iu tr vn cn qu t v cng thng khng sn c. V.3.4 ng truyn HIV v cch phng trnh HIV ly truyn qua ba con ng: Tnh dc, ng mu v m truy n sang con (Lc mang thai, khi sinh hoc khi cho con b).

Tnh dc

Virus HIV c rt nhiu trong mu, trong cc cht dch sinh dc. Do vy, virus c th xm nhp vo mu bn tnh qua c quan sinh dc. Vic sinh hot tnh dc, d c giao hp hay ch tip xc c quan sinh dc, u d n n nguy c ly nhim.

ng mu

HIV c nhiu trong mu. Bm kim tim dng xong m khng ti t trng, hoc tit trng khng tt th vn cn ng mu (d c th khng nhn thy). Do , nu dng chung bm kim tim vi mt ngi mang HIV, bn c th nhim HIV. Nu bn mang HIV, bn c th truy n cho ng i khc theo ng y.

T m truyn sang con

C mt trm ph n nhim HIV sinh con th khong 25-30 tr b nhim. HIV c th ly sang b qua rau thai khi b trong bng m, qua mu v cht dch ca m khi sinh, hoc qua sa m khi m cho con b. Tr s sinh nhim HIV thng khng sng c qu ba nm. V.3.4 SARS . HI CHNG H HP CP -Hi chng h hp cp tnh nng (SARS), l b nh ng h hp gy vim phi khng in hnh nhng ngi b nhim. -Vim phi khng in hnh gy sng v suy yu ph nang, lm gim cung cp mu ti ch cng nh c ch vn chuyn oxy. Mc d nguyn nhn cha c xc nh, song cc Con cy hng nh khoa hc cho rng bnh do virut mi thuc h coronavirus gy ra. Cy hng c coi l th phm truyn virut SARS. Cng c kin cho rng virut bt ngun t ng vt, nhng dng nh n khng c g ging vi cc virut thy trn ngi v ng vt. 1. Virut i vo c th qua ming, mi v mt. 2. Virut n ph nang hay l cc ti trong phi

Virus sars

3. Khi b tn cng, ph nang b sng ln v suy yu, lm gim cung cp mu v vn chuyn oxy. Cc coronavirus l nhm cc virut thng gy ra cc bnh ng h hp trn mc nh v va cho ngi v c lin quan n cc b nh th n kinh, gan, tiu ha v h hp trn ng vt. Trong khi, ngy cng nhiu cc chng c rng virut l nguyn nhn ban u, vn cn rt nhiu cng vic xt nghim tm ra cc c im chnh xc ca n. *Cc triu chng: Cc triu chng chnh gm: - St cao trn 38 C - Ho, th nng, kh th, au u hoc au hng v - i n nhng khu vc c cc ca bnh SARS trong vng 10 ngy gn y hoc - Tip xc trc tip trong vng 10 ngy gn y vi nhng ngi c nhng triu chng trn v i n khu vc b nh hng. Nu c mt trong cc vn trn, cn i khm bnh ngay lp tc. gip cc bc s, bn cn k v vic i li gn y ca b n v nh ng ngi m bn tip xc gn y. *Ly nhim: - Virut c th ly lan qua dch h hp do ht hi - Vi rt cng c th ly lan gin tip nh tip xc vi nh ng vt c dnh dch bi tit ca c th cha vi rt nh in thoi, tay xoay ca b nhim vi rt. Bi v vi rt c th sng t 3-6 gi ngoi c th ngi. - Bnh c th c ly truyn qua khng kh. - Vi rt tn ti trong phn (v nc tiu) nhit phng trong t nht 1-2 ngy, thm ch ti 4 ngy. - Vi rt mt hot tnh gy nhim sau khi tip xc vi cc ch t ti t khu n v c th b cht 56 C. *T phng: Trnh i n cc khu vc b nh hng. - Trnh tip xc trc tip vi bnh nhn SARS. - Thc hin v sinh c nhn: + eo khu trang c phn mm tin cho vic ht hi. + Ra tay nu bn tip xc vi dch h hp (sau ht hi chng hn). + Ra tay trc khi phi ng, s ln mt hoc ming ca bn.

Virus cm

virus cm gia cm

+ Thng xuyn v sinh ni , bp v nh v sinh. * S nguy him: T l t vong khong 3-5%. C ti liu cho rng c th ln n 10%, c bit l nhng ngi cao tui. Nhng ngi b nhim xy ra vim phi c th gy nhiu bin chng. Th trng suy sp rt nhanh, trong vng vi ngy. *iu tr : Hin cha c thuc iu tr c hiu, nhng cc bc s ang ch a tr bnh bng cc thuc khng vi rt v steroid. Nu iu tr sm, phn ln bnh nhn khng mc cc bnh khc, c th hi phc. V.3.5 VIRUT CM V DCH CM GIA CM Virus cm thuc chi Cm (gm cm A, B v C), h Orthomyxoviridae, l nhng virus c genome l RNA i m (negativesense RNA) gm nhiu on (multipartite). Virus cm thng c hnh cu, vi ng knh t 90 n 100 nm. Genome ca n l tm on RNA m ha cho nhiu loi protein khc nhau, trong c cc protein ca enzyme phin m trn khun RNA (RNA dependent transcriptase) cn thit cho s sao chp ca loi virus RNA i m trong t bo. Virus cm sau khi i vo t bo s i vo nhn s dng b my phin m ca nhn cho vi c t o ra cc RNA virus mang m bi virus cm khng c kh nng ng np (capping) u 5. Virus cm c bao bc bi mt lp lipid kp c ngun gc t t bo vt ch khi n bt ra khi t bo. Trn lp mng ny nh ra cc glycoprotein thuc hai nhm chnh l Hemagglutinin (HA) v Neuraminidase (NA). Vai tr ca HA l gip virus gn vo th th trn t bo vt ch kch thch t bo vt ch nut virus vo trong (endocytosis) cn vai tr ca NA th khng r rng lm, c l n gip virus bt ra khi t bo vt ch bng cch ct sialic acid kh i cc glycoprotein ca virus v t bo vt ch. Bn trong lp v lipid kp l lp protein n n bao quanh v nhn (nucleocapsid). Cc loi cm A, B v C khc nhau v s lng cc on RNA cng nh cu trc ca protein nn v protein nhn.

Cm A l loi gy ra cc i dch cho con ngi v vt nui nhiu nht. S khc nhau gia cu trc ca HA v NA ca cc ch ng virus cm khc nhau c s dng phn loi chng. V d chng ta c cc chng virus cm tng gy i dch cho ngi nh H0N1, H1N1, H2N2, H3N2 H7N7, H5N1. iu ng ch l i dch cm thng l p li c tnh chu k, nhiu khi do cng mt chng virus cm gy ra. V d chng H1N1 gy ra 3 i dch cc nm 1947, 1977, 1986 v 1995. Cm B : HA t thay i thng ch gp trn ngi. Cm C: it gp v thng ch gp trn ngi . VI. PHN LOI VIRUT 1. Da vo c th b bnh do virut Virut thc vt (phytophagineae). Virut ng vt (zoophagineae). Virut vi khun (phagineae). Virut cn trng. 2. Da vo tnh cht dch t v tnh cht lm sng ca bnh. Bnh do virut ng h hp. Bnh do virut ng rut. Bnh do virut hng b. Bnh do virut hng thn kinh. Bnh do virut hng ni tng. 3. Da vo cu trc v c im sinh hc.

H virut

Pravoviridae Parovirus Densovirus Adeno_assovirus

Kiu i xng ca virion Khi

ng V bc Dng v cu trc V tr knh ca ca ca axt nucleic nhn ln virion virion ca virut trong t bo 18-26 Khng AND si n Nhn

Papovaviridae Papillomavirus Polimavirus Adenoviridae Mastadenovirus Aviadenovirue Iridoviridae Iridovirus Herpesvisudae Herpervirus Poxviridae Orthopoxvirus Avipoxvirus Capripoxvirus Leporixvirus Parapoxvirus Entomopoxvirus Picornaviridae Enterivirus Rhinovirus Calicivirus Reoviridae Reovirus Orbivirus Togaviridae Alphavirus Flavivirus Ribivirus Pestivirus Orthomyxoviridae Inluuenzavirus Paramyxoviridae Paramyxovirus Morbillivirus Retrovoridae Onornamavirinae Lentivirinae Spumavirinae Rhabdoviridae Vesiculovirus

Khi Khi Khi Khi Phc tp

44-55 55 45 70-90 130-300 120-150 300-450 170_260

Khng Khng C

AND Si kp AND si kp

Nhn Nhn Nhn Nguyn sinh chat nhn nguyn sinh cht

AND si kp C AND si kp C AND V phc si kp tp

20-30 Khi 35-40 60-80 Khi Khi Tr 40-70 80-120 150 C c khng khng

ARN Si n ARn si kp

nguyn sinh cht nguyn sinh cht

ARN si n

nguyn sinh cht

Khi

100

ARN si n ARN si n ARN si n

nguyn sinh cht nguyn sinh cht nguyn sinh cht

Tr

130-300

c

ARN

nguyn

Lyssavirus Sigmavirus Bunyavirudae Bunyavirus Arenavirudae Arenavirus Coronviridae coronavirus

si n 90-100 50-500 100 c c c ARN si n ARn si n ARn si n

sinh cht nguyn sinh cht nguyn sinh cht nguyn sinh cht

CHNG IV SINH L HC VI SINH VT 4.1 DINH DNG CA VI SINH VT Cc cht dinh dng i vi vi sinh vt l bt k ch t no c vi sinh vt hp th t mi trng xung quanh v c chng s dng lm nguyn liu cung cp cho qu trnh sinh tng hp to ra cc thnh phn ca t bo hoc cung cp cho qu trnh trao i nng lng. Qu trnh hp th cc cht dinh dng tho mn mi nhu cu sinh trng v pht trin c gi l qu trnh dinh dng. Cht dinh dng phi l nhng hp cht c tham gia vo cc qu trnh trao i ch t ni bo. Thnh phn ho hc ca t bo vi sinh vt quyt nh nhu c u dinh dng ca chng. Thnh phn ho hc ca cc cht dinh dng c cu to t cc nguyn t C, H, O, N, cc nguyn t khong a v vi lng. Lng cc nguyn t cha cc vi sinh vt khc nhau l khng gi ng nhau. Trong cc iu kin nui cy khc nhau, tng ng vi cc giai on pht trin khc nhau, lng cc nguyn t cha trong cng mt loi vi sinh vt cng khng ging nhau. Trong t bo vi sinh vt cc hp cht c phn thnh hai nhm ln: (1) nc v cc mui khong; (2) cc ch t hu c.

90 % khi Nc v mui khong. Nc chim n 70 lng c th vi sinh vt. Phn nc c th tham gia vo qu trnh trao i cht ca vi sinh vt c gi l nc t do. a phn nc trong vi sinh vt u dng nc t do. Nc kt hp l phn nc lin kt vi cc h p cht h u c cao phn t trong t bo. Nc lin kt mt kh nng ho tan v lu ng. 5 % khi lng kh ca Mui khong chim khong 2 t bo. Chng thng tn ti di cc dng mui sunfat, phosphat, cacbonat, clorua...Trong t bo chng thng dng cc ion. Cc ion trong t bo vi sinh vt lun lun tn ti nhng t l nht nh, nh m duy tr pH v p sut thm thu thch hp cho tng loi vi sinh vt. Cht hu c trong t bo vi sinh vt ch yu c cu to bi cc nguyn t: C, H, O, N, P, S...Ring cc nguyn t C, H, O, N chi m 97% ton b cht kh ca t bo. l cc nguyn t ch yu c u t o ti 90 nn protein, axit nucleic, lipit, hydrat- cacbon. Trong t bo vi khun cc hp cht i phn t ch chim 3,5% , cn cc ion v c ch c 1%.Vitamin cng c s khc nhau rt ln v nhu cu ca vi sinh vt. C nhng vi sinh vt t dng cht sinh trng, chng c th t tng hp ra cc vitamin c n thi t. Nh ng cng c nhiu vi sinh vt d dng cht sinh trng, chng i h i phi cung c p nhiu loi vitamin khc nhau vi liu lng khc nhau.

4.1.1 Ngun thc n cacbon ca vi sinh vt Cn c vo ngun thc n cacbon ngi ta chia sinh vt thnh cc nhm sinh l t dng v d dng. Tu nhm vi sinh vt m ngun ccbon c cung cp c th l cc cht v c (CO2, NaHCO3, CaCO3...) hoc cht hu c. Gi tr dinh dng v kh nng hp th cc ngun thc n khc nhau ph thuc vo hai yu t: mt l thnh phn ho h c v tnh cht sinh l ca ngun thc n ny, hai l c i m sinh l c a t ng lo i vi sinh vt. Thng s dng ng lm ngun cacbon khi nui cy phn ln cc vi sinh vt d dng. Trong cc mi trng cha tinh bt trc ht phi 700C, sau un si ri mi a i tin hnh h ho tinh bt nhit 60 kh trng.

Xenluloza c a vo cc mi trng nui cy vi sinh vt phn gi i xenluloza di dng giy lc, bng hoc cc dng xenluloza . Khi s dng lipit, parafin, du m... lm ngun ccbon nui cy mt s loi vi sinh vt, phi thng kh mnh to t ng git nh c th ti p xc c vi thnh t bo ca vi sinh vt. Cc hp cht hu c cha c C v N (pepton, nc tht, nc chit ng, nc chit nm men, nc chit i mch, nc chit gi u...) c th s dng va lm ngun C va lm ngun N i vi vi sinh vt. Trong cng nghip ln men, r ng l ngun cacbon r tin v rt thch hp cho s pht trin ca nhiu loi vi sinh vt khc nhau. Ngun C (Carbon sources) - T dng (autotroph) - D dng (heterotroph) Ngun nng lng - Dinh dng quang (phototroph) Dinh dng ho (chemotroph) Ngun in t - Dinh dng v c (lithotroph) - Dinh dng hu c (organotroph) CO2 l ngun C duy nht hay ch yu Ngun C l cht hu c nng Ngun nng lng l nh sng nng Ngun nng lng l nng lng ho hc gii phng ra t s oxi ho hp cht hu c Dng cc phn t v c dng kh cung cp in t Dng cc phn t hu c dng kh cung cp in t

Ngun nng lng, Hydrogene, Loi hnh dinh dng i din in t, carbon Vi khun sulfur, - T dng quang nng v Quang nng; H2, mu tm, mu c H2S, S hoc lc, vi khun (photolithoautotrophy) H2O; CO2 lam

- D dng quang nng Vi khun phi lu hu c Quang nng; cht hunh mu ta, (photoorganoheterotro hu c mu lc phy) Vi khun oxi ho S, Ho nng (v c), Vi khun H2, H2S, - T dng ho nng v c hydrogene, vi Fe2+, NH3 (chemolithoautotrphy) khun nitrat hoc NO2-, ho, vi khun CO2 oxi ha st ng vt nguyn sinh, nm, phn - D dng ho nng hu c ln cc vi khun Ho nng (hu c); (chemoorganoheterotrop khng quang Cht hu c hy) hp (bao gm c cc vi khun gy bnh) Ngun thc n nit ca vi sinh vt Ngun nit d hp th nht i vi vi sinh vt l NH3 v NH4+. Mui nitrat l ngun thc n nit thch hp i vi nhiu loi to, nm si v x khun nhng t thch hp i vi nhiu loi n m men v vi khun. Thng s dng mui NH4NO3 lm ngun nit cho nhiu loi vi sinh vt. Ngun nit d tr nhiu nht trong t nhin chnh l ngun kh nit t do (N2) trong kh quyn. Vi sinh vt cn c kh nng ng ho rt tt nit cha trong cc th c n hu c. Ngun nit hu c thng c s dng nui cy vi sinh vt l pepton loi ch phm thu phn khng trit ca mt ngun protein no y. Nhu cu v axit amin ca cc loi vi sinh vt khc nhau l rt khc nhau. Ngun thc n khong ca vi sinh vt

Khi to cc mi trng tng hp (dng nguyn liu l ho ch t) b t bu c phi b sung cc nguyn t khong cn thit. Nng cn thit ca tng nguyn t vi lng trong mi trng thng ch vo khong 10-6 108 M. Nhu cu khong ca vi sinh vt cng khng ging nhau i vi t ng loi, tng giai on pht trin. Nhu cu v cht sinh trng ca vi sinh vt Mt s vi sinh vt mun pht trin cn phi c cung cp nhng ch t sinh trng thch hp no . i vi vi sinh vt ch t sinh trng l m t khi nim rt linh ng. Cht sinh trng c ngha nht l nhng cht hu c cn thit cho hot ng sng ca mt loi vi sinh vt no khng t tng hp c ra chng t cc cht khc. Nh vy nhng cht c coi l cht sinh trng ca loi vi sinh vt ny hon ton c th khng phi l cht sinh trng i vi mt loi vi sinh vt khc. Thng thng cc cht c coi l cc cht sinh trng i v i mt lo i vi sinh vt no c th l mt trong cc cht sau y: cc gc ki m purin, pirimidin v cc dn xut ca chng, cc axit bo v cc thnh ph n ca mng t bo, cc vitamin thng thng... 4.2 H HP V CC QU TRNH LN MEN 4.2.1 H HP HIU KH V K KH Thng thng khi cht nhn electron cui cng l oxi phn t th ng i ta gi l qu trnh h hp v vi sinh vt thuc dng ny g i l vi sinh v t hiu kh. Khi cht nhn electron cui cng l mt cht khc khng ph i l oxi t do, th gi l qu trnh ln men v tc nhn gy ln men g i l vi sinh vt k kh. Trong s cc c th k kh c loi c th dng ch t nhn electrron l ch t hu c, loi khc cht v c. i vi loi u, ng i ta g i l ln men (ngha hp), i vi loi sau ngi ta gi l h hp k kh. - H hp i vi mt vi khun l do n c m t chui v n chuy n electron lin kt mng t bo v s i vo ca mt dng electron theo mt chiu v mt dng tng ng cc proton theo chiu ngc li, m hp cht lm cht nhn electron cui cng c th l O2, NO3-, h p ch t hu c, - Ln men ch s c mt ca chui vn chuyn electron nm trong t bo cht, khng c s t ng i qua ca dng electron hoc proton phn bn ny v phn bn kia ca t bo. V phng din chuyn ho

nng lng, ln men cng l mt qu trnh oxi ho kh, nhung cht nhn electron cui cng l cc hp cht hu c, ch khng phi l cc phn t oxi. Qu trnh ny cng gii phng nng lng nhng t hn nhiu so vi qu trnh h hp. Oxi ho hon ton mt phn t glucoz (h hp) thnh CO2 v H2O trung bnh sinh ra c 2800kJ, trong khi ln men mt phn t glucoz thnh axit lactic ch gii phng c 94kJ 4.3 SINH TRNG V PHT TRIN, PHN B Khi ni v sinh trng v pht trin ca vi khun tc l cp ti sinh trng v pht trin ca mt s lng ln t bo ca cng mt loi. Do t bo vi khun qu nh nn vic nghin cu chng gp nhiu kh khn. S tng s lng khng phi bao gi cng din ra cng vi s tng sinh khi.V vy cn phi phn bit cc thng s v hng s khc nhau khi xc nh s lng v khi lng vi khun.Bng cc thng s v hng s s dng khi xc nhs lng v khi lng vi khun: Cc thng s cn xc S lng vi khun nh Khi lng vi khun

Mt 1)Thi gian tng n v th tchS lnNng 1)Thi gian th tng i sau mt n vh g vi khun (s t(h vi khun (sinh thi gianThi gian cnbo/ ml)Hng s tc khi kh/ ml)Hng s tc sinh trng i thit cho s tng i phn chia C (h (h) (h) Tu theo tnh cht thay i ca h vi khun c hai ph ng php nui c y vi khun c bn: nui cy tnh v nui cy lin tc.Trong vi sinh v t h c khi ni n sinh trng l ni n s sinh trng ca c qu n th . D i y chng ta kho st mu th nghim l tng theo di s sinh tr ng v pht trin ca vi khun. Nu s t bo ban u l No th sau n ln phn chia s t bo tng cng l N: N=No2n (1.1) Gi tr n (s th h) c th tnh nh logarit thp phn: logN=logNo+nlog2 Thi gian th h (g) c xc nh theo cng thc

Sinh trng v pht trin ca vi khun trong iu kin nui cy tnh Phng php nui cy m trong sut thi gian ng i ta khng b sung thm cht dinh dng v cng khng loi b sn phm cui cng c a s trao i cht gi l nui cy tnh (qun th t bo b gii hn trong mt khong thi gian nht nh). S sinh trng trong mt h th ng ng nh vy tun theo nhng quy lut bt buc [theo cc pha lag (pha m u), pha log, pha n nh v pha t vong]. Pha lag tot1titr hlog2N12Hnh 1.8 . th biu din pha lag:1- ng thng l tng;2- ng thng thc t;(r- Thc t; i- L tng)hlog2Ni= log2NrPha ny tnh t lc bt u cy n khi vi khun t c tc sinh trng cc i. Trong pha lag vi khun cha phn chia nhng th tch v khi lng t bo tng ln r rt do qu trnh tng hp cc cht trc ht l cc hp cht cao phn t (protein, enzim, axit nucleic) di n ra m nh m. di ca pha lag ph thuc trc ht vo tui ca ng ging v thnh phn mi trng. Thng t bo cng gi th pha lag cng di. Vic tm hiu di ca pha lag l cn thit trong vic phn on c tnh ca vi khun v tnh cht ca mi trng. thun ti n cho vi c tnh ton ngi ta chuyn cc phng trnh ny thnh cc ph ng trnh ng thng bng cch s dng logarit: lnN=Ctln2+lnNo =t+lnNo V log2N=log2e+log2No=Ct+log2No Pha lag c coi nh l khong cch thi gian gia ng th ng th c nghim (hoc thc t) v ng thng l tng song song vi n khi m vi khun, gi d khng phi tri qua pha lag. Gi thi gian c a pha lag l TL, ta c : TL=trti =t1to(1.11) Phng trnh ca ng thng l tng l: logNi=Cti+logN0

V: logNi=logNr C th vit: logNr=Cti+logNo logNrlogNo=Cti Pha log Trong pha ny vi khun sinh trng v pht trin theo lu th a, ngha l sinh khi v s lng t bo tng theo ph ng trnh: N = t. Trong pha ny kch thc ca t bo, thnh phn ho hc, No.2ct hay X = Xo.C hot tnh sinh l... khng thay i theo thi gian. Nu ly trc tung l logarit ca s t bo th ng bi u di n sinh trng theo lu tha ca vi khun s l ng thng. V pha sinh tr ng theo lu tha ca vi khun c biu din bng s ph thuc theo ng thng gia thi gian v logarit ca s t bo nn pha ny c g i l pha logarit. Thng dng logarit c s 2 l thch h p h n c v s thay i mt n v ca log2 trn trc tung chnh l s tng i s l ng vi khun v thi gian cn tng mt n v ca log2 li l th i gian th h. Thi gian th h (hoc thi gian tng i) g, hng s l ba thng s quan trng catc phn chia C v hng s tc sinh trng c th tnh c t phng trnh:pha log. Trong iu kin th nghim c th iu chnh sao cho tc sinh trng ca vi khun ch mn cm, ngha l ch ph thuc vo mt yu t. Trong trng hp nh vy yu t cho l yu t hn ch tc sinh trng. Cht dinh dng hn ch c th l ng, axit amin, cht v c. vi nng chtMi quan h gia cc hng s C v dinh dng hn ch c biu din qua cc phng trnh: C=Cmax Pha n nh

Trong pha ny qun th vi khun trng thi cn bng ng hc. S t bo mi sinh ra bng s t bo c cht i. Kt qu l s t bo v c sinh khi khng tng cng khng gim. Nguyn nhn tn ti ca pha n nh l do s tch lu cc sn ph m c ca trao i cht v vic cn kit cht dinh dng. S tng sinh khi tng cng t l thun vi nng ban u ca ch t dinh dng hn ch. G = K.C trong : G - tng sinh khi tng cng; C - nng ban u ca cht dinh dng hn ch; K - hng s hiu sut:

Pha t vong Trong pha ny s lng t bo c kh nng sng gim theo lu tha. Cha c mt quy lut chung cho pha t vong. S cht ca t bo c th nhanh hay chm, c lin quan n s t phn hay khng t phn. Trong trng hp mi trng tch ly cc axit l nguyn nhn lm ch t t bo tng i r th nng cht dinh dng thp di mc cn thi t v hu qu l gim hot tnh trao i cht, phn hu dn dn cc ch t d

tr v cui cng dn n s cht hng lot ca t bo. Ngoi c tnh ca bn thn chng vi sinh vt, tnh ch t ca cc s n ph m trao i ch t tch lu li cng nh hng n tin trnh ca pha t vong. Sinh trng v pht trin ca vi khun trong qu trnh nui cy lin tc Trong thc tin sn xut cn cung cp cho vi sinh vt nh ng iu ki n n nh trong mt thi gian di chng vn c th sinh trng trong pha log. D nhin mt mc no c th cy chuyn t bo nhiu ln vo mi trng dinh dng mi. n gin hn nn a lin tc mi trng dinh dng mi vo bnh nui cy vi khun ng th i loi kh i bnh mt lng tng ng dch vi khun. y chnh l c s c a ph ng php nui cy lin tc trong cc thit b nui cy lin tc. Gi s c mt bnh nui cy trong vi khun ang sinh trng, pht trin. Lin tc b sung vo bnh mi trng mi c thnh ph n khng i. Th tch bnh nui cy khng i, ngha l lng mi trng c b sung cn bng vi lng mi trng i ra cng tc . Gi th tch bnh l V (lt), tc dng mi trng i vo l f (lt/h) th tc pha long (h s pha long) D s l f/V. i lng D bi u th s thay i th tch sau 1 gi. Nui cy tnh c coi nh h thng ng, qun th t bo sinh trng trong phi tri qua cc pha m u, logarit, n nh v t vong. Mi pha sinh trng c c trng bi nhng iu kin nht inh. Vic t ng ho cc pha l kh thc hin. Nui cy lin t c, tri l i, l h th ng m c khuynh hng dn n vic thit lp mt cn bng ng hc. Yu t thi gian y, trong phm vi nht nh, b loi tr. T bo c cung cp nhng iu kin khng i, nh vic iu chnh t ng.

CHNG 5 DI TRUYN V BIN D VI SINH VT 5.1 DI TRUYN VI SINH VT

5.1.1 c im di truyn vi sinh vt + Vi sinh vt c cu to rt n gin, cho nn trong di truy n vi sinh v t c s sai khc nht nh so vi sinh vt bc cao. + T bo VSV thng n bi, sinh sn VSV cc nhanh, do nghin c u di truyn VSV bitees c kt qu nhanh hn cc sinh vt bc cao. + VSV cng nh sinh vt bc cao, cc phn t mang thng tin di truyn cha trong mt vng xc nh ca t bo, theo mt trnh t mch thng v c truyn ln lt t t bo cho sang t bo nhn. + Nghin cu di truyn VSV gp phi nh ng kh khn ch y u l: kch th c v cng nh b, nhiu vi cu trc ca t bo nm ngoi phm vi kim sot ca my mc. 5.1.2 Nhn t di truyn ca VSV. - VSV th nhn t di truyn l axit nucleic (AND v ARN ) l nguyn liu di tryn s cp m t trc tip cu to nn cc nhim sc th v cc gen cng nh cc plasmit VSV. - ARN l nguyn kiu di truyn th cp, n tham gia vo qu trnh phin m thng tin di truyn 5.1.3 S lc v s trao i di truyn VSV v c ch sao chp li a S trao i di truyn b C ch sao chp li Khi AND sinh sn, 2 si l xo dui ra, mi lin kt hiddro gi a cc bazo nito b t. hai nhim sc th tch ri nhau, tng si 1 t sao chp thnh m t s i m i tng ng vi n. 5.4Qu trnh truyn nguyn liu di truyn vi sinh vt 5. 4.1 Bin np (transformation ) nh ngha Bin np l s bin i genotip ca vi khun th nhn di nh h ng ca AND t vi khun th cho. AND di th dung dch do mt th vi khun th cho gii phng ra, c truyn i khng c s can thip ca mt nhn t c u trc nhim sc th hoc epixom, hoc ca phage vecto. iu kin ca qu trnh bin np: qu trnh bin np ch xy ra khi vi khaunar nhn mt tnh trng sinh l c bit ( khong 1- 15% t bo qu n th thng thng giai on pht trin gim ) tnh trng ny lm thay i tnh ch t b mt t bo nhn c cc yu t cm ng enzyme c bit trn c cc o n phn t AND c th xm nhp c trn b mt t bo nh n c cc y u t c m ng cho on phn t AND c th c nh c chng 30- 70 vng cm ng nh th on AND nhp vo t bo c tch i, v mt mch n c ghp vo NST ca t bo nhn. Qu trnh ny gi l s ti t hp (recombination ).

Grifith l ngi u tin pht hin s bin np ph cu khu n (streptococcus pneumoniae, tn c l Diplococcus pneumonae hay pneumococcus ) vo nm 1928 vi khun ny c hai dng khc nhau - Dng gy bnh cho ng vt hnh thnh khun lc lng k hiu l S - Dng khng gy bnh hnh thnh khun lc nhm k hiu R. n u tim vi khun sng chng s th lm cho chut nht ch t, tim s ch t cho qua s l nhi t (h nng ) th chut vn sng, cn tim vi khun ch ng R cho chu t thi chu t vn sng , nhng ng thi tim R v S cht th l i lm chu t ch t v sau trong mu chut cht phn lp c chng S c trng. Cc th nghim sau (Avery, Macleod v Mecarty, 1946 ) cho thy nu s l dch S ch t c tinh ch vn c nng lc bin np Invitro v nu x l b ng Dnase th lm m t ho t tnh bin np ca dch ny trong khi x l bng protease vn gi nguyn tnh bin np iu chng minh rng AND ch khng phi l protein l vt ch t mang thng tin di truyn. - Cho n nay nhng tnh trng c bin np c bit l kh nng t ng hp yu t sinh trng, kh nng s dng sinh trng, kh nng khng thuc, kh nng sinh c tnh hin tng ny c vn dng rng ri trong k thut di truyn. VD: 5. 4.2. Ti np

(chuyn np _ transduction ) nh ngha: ti np l s vn chuyn vt cht di truy n nh phage (bacteriophage hay thc khun th ) l cc virut k sinh vi khun, c 2 loi phage. Cc phage c lm tan vi khun. tuy vy cc phage n ha c hai giai o n thay

th nhau trong chu trnh pht trin, chng c th tr thnh phage c khi m mi trng c tc nhn (ha, l ) gy t bin. Khi phage hp bm trn mng t bo vi khu n c hi u b ng th th lng ui, ATP- ase ng ui ca phage c hot ha phn gii ATP gi i phng nng lng lm co rt v ui, kt qu l ng ui chc thng mng t bo vi khun v lm AND phage theo ng ui ny xm nhp vo t bo vi khun, sau khi xm nhp AND phage c tn ti c lp trong t bo ch t i u chnh qu trnh tng hp protein phage v lm phn h y AND c a vi khu n , trong qu trnh lp rp v protein phage li cha mnh AND vi khun ( to thnh phage khuyt tn ) khi gii phng ra ngoi cng ca phage khc do dung gi i t bo phage khuyt tn nay li tip tc hp bm ln t bo mi v a on AND ca t bo c vo t bo mi. mt s phage gi l phage n ha sau khi xm nhp vo t bo cht ca vi khun, AND n nhp vo cu trc phn t AND NST c a vi khu n dng tin phage (prophage ). trng thi episome ny b gen c a phage n ha c truyn cho th h sau ca vi khun tng t cc gen khc ca NST. Cc vi khun mang prophage c gi l vi khun dung nguyn (lysogennic bacteria ) do nhng vi khun ny mang mm mng ca qu trnh dung khun sau ny, khi chuyn sang trng thi c vi khun dung nguyn tip tc sinh trng bnh thng. tuy nhin khi gp iu kin mi trng c cc yeus t gy t bi n th phage chuyn sang trng thi c lm vi khun dung gii khi cc prophage t sao chp thnh nhng phin bn trng thi c lp trong t bo cht v b t u chu trnh dung gii vi khun. trong qu trnh sao chp cc phage m i hnh thnh c th mang theo AND ca phage v on AND (nm k bn ) cua NST vi khun khi xm nhp t bo mi, cc phage mang gen NST th c hin ch c nng mang vt cht di truyn t t bo cho sang t bo nh n. s ti np ph bi n rng ri v c nghin cu vi khun h enterobacteriaceac. ecoli l cc phage T v P-1, shigella P-1, salmonella typhimurum P-22. cc phage t i n p pseudomanas v proteus cng bit n. qu trnh ti np c th vn chuy n mt hoc mt s gen bt k nh nu trn c gi l ti np chung hay t i n p khng c hiu (nh ti np do phage P-1 v P-22 Ecoli Shigella v Salmonella. Nhiu phage ch c th ti t hp vo 1 v tr (Locus) nht nh trong genome k ch chnh v vy chng ch c th vn chuyn nhng gen phn b gn locus ny m thi hin tng ny gi l ti np c hiu. Ni chung vi khun chuyn np ng vai tr trong lan truy n c tnh, lan truyn khng nguyn thn (gy phn ng cho min dch) v nng cao kh nng tng hp cc cht yu t sinh trng. 5.4.3 Tip hp

Tip hp l mt hin tng truyn mt phn vt ch t di truy n theo m t chiu t t bo cho (th cho l vi khun c ) sang t bo nh n (th nh n l vi khun ci), vic truyn dn ny i hi s tip xc v s kt i gi a hai vi sinh vt. dn ti s hnh thnh mt hp t hp nhn (Meoyzot ) ch a h gen ca vi sinh vt c th tinh v mt mnh ca h gen ca vi sinh v t cho. Hai thnh phn ny kt hp li thnh mt nhim sc th duy nh t. nh ng trng thi nh bi ch l tam thi. trong s phn chia ny, nh ng t bo sinh ra do ti p h p c gi l th ti t hp (Recombinant ). Qu trnh truyn vt cht di truyn ch din ra mt chiu t t bo c (F+) sang t bo ci (F-). iu ny c Lederberg v Tatum chng minh ln u tin vo nm 1964 trn cc bin chng E.coli K-12. kh nng cho c a t bo c quyt nh bi s c mt ca yu t di truyn ngoi NST l F ( fertility factor, s-factor, yu t gii tnh ). Cc thut ng t bo c v t bo ci c dng theo h th ng nh danh hin i t nm 1976. Trn b mt t bo F+ c cc nhung mao c bit _pili gii tnh c th hp th cc phage c bit s lng pili gii tnh rt t (khong 2-3). ng knh trong khong 25 A c th cho php si AND ca t bo i qua khi n ti p xc vi t bo nhn. Yu t ngoi NST iu khin qu trnh tip hp ( conjugative plasmid ) nhng plasmid ny c th iu khin tng hp coliein ( colj, colv2, colv3 ). Plasmid iu khin tng hp enterotoxin E.coli, v mt vi khng nguyn khc. Qu trnh tip hp ca plasmid F ti t h p trong AND m ch vng c a NST bt u t khi 2 t bo c v ci tip xc nhau. Khi mt on ca NST k bn yu t F b ct v dui ra m tr nn c cu trc thng. u NST t do ny tch ra v t sao thnh 2 si h ng v pha pili gi i tnh v c chuy n theo pili ny sang t bo F- . Bi v plasmid F nm cui chui thng NST nn n khng c truyn qua t bo F - v trong qu trnh tip hp ngn ngi AND nhim sc th thng b t on, v nh ch mt phn NST ca t bo F + c chuyn sang t bo F- nhng chng c tng sut bin np gen NST cao c gi l chng Hfr (chng c tn sut bin np cao). Trong trng hp pili gii tnh t do trong t bo cht hai hin tng ny c th gp l bi n n p m t phn genome plasmid F hoc bin np ton b genome plasmid trong tr ng hp u ch 1 s gen ca plasmid F c chuyn sang v c th ti t hp vo NST t bo nhn trong trng hp sau: t bo nhn tr thnh t bo F + hin tng ny gi l s hng ha ( c ha) t bo ci. 5.2 BIN D VI SINH VT V S T BIN 5.2.1. Cc loi bin d a. Bin d phenotip

L nhng bin d v kiu hnh, tam thi v thun ngh ch, khng n nh c a ton b qun th vi sinh vt, gy ra do nhng iu kin ca mi trng trong vi sinh vt bt buc phi sng v sinh sn. nh ng biu hi n ny xu t hi n ch m v mt i vi s bin mt ca yu t lm xut hin chng, chng khng phi l sinh ra do di truyn. a.1. Bin d v hnh thi vi sinh vt Hnh thi vi sinh vt khng phi l c nh. Nhng bin d v hnh thi c th sinh ra di nh hng ca nhng yu t khc nhau, c lin quan n tui c a vi sinh vt v ca mi trng xung quanh. Bin d v hnh thi trong qu trnh sinh sn Bin d v hnh thi di nh hng ca ngoi cnh: cu to ha hc ca mi trng nhng iu kin l ha khng thun li ca mi trng, nhng cht tiu c, st trng, khng sinh, ha tr liu. a.2.Bin d v dng khun lc Nhng bin d trn khun lc pht trin trn mi trng c t nh ng vi khun cng loi hin nay c coi nh nhng bin d gy ra do ngo i c nh. Nhng tn thng trong cu trc ca vi sinh vt hnh thnh nhng khu n l c ring bit ny, lm bin i dng ca nhng khun lc ny. Bin d genotip ( t bin ) Bin d genotip l nhng bin d t ngt, xut hin mt cch ng u nhin, khng d nh trc v khng lin tc mt s c th him hoi ( 1x 10 -5 n 1x10-8) ca mt qun th sinh vt. chng tng i c l p vi mi tr ng xung quanh, c tnh cht c nh, vnh cu, di truyn. Nhng tc nhn gy t bin vt l (tia phng x hoc ha hc ch lm tng gp bi tn s ca t bin ny) 5.2.2 Nhng biu hin ca s t bin vi khun - C kh nng pht sinh t bin - Dng khun lc pht trin trn mi trng dinh dng c - S hnh thnh sc t trn mi trng chon lc - S hnh thnh ni t - Kh nng tng hp mt cht chuyn ha hoc mt yu t sinh trng - Kh nng ln men ng - c lc ca vi sinh vt kim tra bng cch tim nhim qua ng vt th nghim. - Tnh khng nguyn kim tra bng cch cy trn mi trng c huy t thanh c hiu - S mn cm i vi khng sinh 5.2.3. Th t bin t pht v th t bin cm ng a. Th t bin t pht

Ngi ta pht hin cc th t bin t mi trng chn lc. nhng s chn lc trc tip ny c th lm xut hin mt th t bin ch khng pht hin s c mt ca mt th t bin hnh thnh t trc. C hai phng php c p dng: phng php th nht chng minh s c mt ca nhng th t bin t pht c trc khi phn lp trn mi trng chn lc ( phng php thng k ) Phng php th hai l phng php thc nghim theo k thut ng du Ldebec. b. Th t bin cm ng bng nhng tc nhn gy t bin Cc tc nhn gy t bin c th lm tng rt nhi u l n t n s t bin. l cc tc nhn vt l nh: tia phng x ( tia X, tia t ngo i ) c c ng thp hoc nhng tc nhn ho hc ( oxi gi, axit nitoric, cacbua hidro gy ung th ). c. cc loi th t bin - Bin d ca khun lc vi khun - Th t bin ha sinh hoc dinh dng th t bin sinh trng - Nhng th t bin khng Tm li: t bin l mt qu trnh gy ra do tc nhn t bin tc ng ln cc cu trc ca gen, gy ra nhng sai st trong qu trnh sao li AND. 5.3 NHNG THNH TU TRONG NGHIN CU DI TRUYN VI SINH VT 5.3.1. Cc phng php chn lc ging khng dng tc nhn gy t bin - Phng php chn lc t nhin: da vo mc tiu v yu cu sn xut m t chn c nhng ni VSV thch nghi v t n ti trong mi tr ng theo mun. - Phng php chn lc nhn to: theo phng php ny ngi ta tch nhng ni VSV mang nhng du hiu hu ch cn thit t qun th VSV nui cy trn mi trng c, mi trng phn lp thch ihoc thch phn lp c bit v chn lc nhng khun lc in hnh p ng yu cu sn xut. - S dng c ch lai: ngi ta phi 2 dng vi sinh vt to th lai c nhng du hiu tri ca VSV b m (lai lng bi) hoc c th kt h p cc tnh trng ca b m ( ti t hp ). 5.32. Cc phng php chn lc ging dng tc nhn gy t bin - To ging vi sinh vt bng tc nhn sinh hc - To ging vi sinh vt bng tc nhan ha hc - To ging vi sinh vt bng cc tc nhn vt l CHNG 6

NH HNG CA IU KIN NGOI CNH N VI SINH VT V S PHN B CA VI SINH VT TRONG T NHIN NH HNG CA IU KIN NGOI CNH I VI VI SINH VT 1. nh hng ca cc nhn t vt l nh hng m Hot ng ca vi sinh vt iu lin quan n nc, VSV cn nc trng thi t do, do qu trnh trao i cht nu thiu nc s c hi n t ng lo i n c ra khi t bo, lm cho t bo c th b cht. Nhit - Khi nhit thp di 00C lm ngng qu trnh sinh trng, pht trin ca vi sinh vt ng dng: bo qun ging vi sinh vt, thc n v cc vt liu cn thit - Khi nhit cao hn 00C VSV c s sinh trng v pht trin. Mi loi VSV u c nhit thp nht, cao nht v nhit thch hp cho s sinh tr ng c a ring n. ng dng: kh trng dng c, nguyn liu trong lnh vc ch bin thc phm, y t, VSV hc p sut thm thu Mng t bo l mt mng bn thm, nng ch t ha tan trong dung d ch m VSV tn ti quyt nh p sut thm thu. ng dng: thng dng mui, ng nng cao trong bo qun v ch bin thc phm. Cc tia bc x a s VSV khng cn nh sng, tc ng ca nh sng mt tri c th trc tip lm ph hy t bo, ho gin tip to ra cc cht c trong mi trng, gy h i cho VSV. ng dng: cc tia bc x c s dng trong kh trng, tiu c, trong bo qun, ch bin v cng tc y, VSV hc. 2. nh hng ca cc nhn t ha hc pH Gii hn pH ca s sinh trng l gii hn pH t c c ti u n c c i m VSV c kh nng sinh trng. Trong gii hn ny c pH thch h p nh t, m VSV c s sinh trng v pht trin cao nht. a s VSV thch ng pH 4,5 9,0. Cc cht xc trng, c ch, dit khun - Cht xc trng l nhng cht c th gy cht VSV gy bnh hoc khng gy bnh nhng khng git cht c nha bo. I.

- Cht c ch l nhng cht lm ngng qu trnh sinh trng, pht trienr, VSV khng b git m trng thi tim tng. - Cht dit khun: l nhng cht c th git ton b vi khun k c nha bo ( hay bo t), mt cht va xc trng, c ch hay dit khun ty thuc vo n ng , thi gian, loi VSV tc ng v cc yu t khc. Cc cht ha tr liu: gm nhng cht c th tng hp c bng phng php ha hc. c tc dng c i vi VSV nhng khng gy hi cho ng vt. Cht khng sinh: l cht do VSV sinh ra, ngay nng thp kgangs sinh cng c kh nng c ch hoc tiu dit cc VSV mt cch c hiu, mi khng sinh ch tc ng ln mt vi khun hoc mt nhm vi khun bng cch gy ri lo n phn ng VSV ngng phn t. Tiu c, kh trng, tit trng - C ch tc dng ca cc yu t tiu c, kh trng Gy tn hi n mng nguyn sinh cht, lm thay i tnh th m c a mng, tr ngi n qu trnh trao i cht. Gy tn hi n thnh phn nguyn sinh cht t bo, lm tr ngi hoc ngng cc phn ng trao i cht. Gy nn s km hm hoc mt hot tnh men trong t bo. Thay i qu trnh sinh tng hp trong t bo lm hnh thnh cc ch t khng cn thit cho qu trnh sinh trng, pht trin ca t bo. Ph v hoc hy hoi ton b t bo. - Tiu c, kh trng: tiu c l bi php loi tr v tiu dit mm bnh ngoi cnh bn ngoi c th ngi v ng vt, kh trng l mt bin php laoij tr hon ton VSV c trong mt mi trng no bng cch tiu di t hay lo i b chng. Bin php tiu c kh trng - Bng cc cht ha hc - Bng nhit - Bng phng php lc 3. Tc ng ca cc yu t sinh vt hc Quan h cng sinh: l mi quan h hai bn cng c l i gi a hai sinh v t khc nhau, hot ng sng ca sinh vt ny s thc y s sinh trng v pht trin ca sinh vt kia v ngc li, mi quan h gi a chng kh tch ri. nu chng tch ri s nh hng n hot ng sng ca chng. Quan h tng h: khng c s rng buc mt cch cht ch gia cc sinh vt trong mi quan h ny, chng c th tch ri nhau, khng cn n nhauvaf gia chng ch c mt bn nhn m khng h c s gip bn kia.

Quan h i khng: y l mi quan h khng c li, gy ra nhng nh hng hn ch hoc tiu dit loi tr nhau biu hin trn cc mt nh tranh chp cht dinh dng, tit ra nhng sn phm c hi. Quan h k sinh: l mi quan h gia hai c th m mt bn c li, m t bn b hi. II. Phn b ca vi sinh vt trong t nhin 1. S phn b ca vi sinh vt trong t 1.1. Mi quan h gia t v vi sinh vt t - dy ca tng t canh tc - c im v tnh cht ca t - Thi tit kh hu - R cy h u 1.2. Tc dng ca vi sinh vt trong t Tng hp cc cht cn thit cho s pht trin ca cy trng v tng ngun dinh dng cho t Tng cng s phn gii cc hp cht hu c trong t gp ph n hnh thnh ch t mn trong t tng ph trong t. Tng cng s chuyn ha cc hp cht hu c trong t: VSV m trong phn ln l vi khun c tc dng chuyn ha cc hp cht c cha N v khng cha N. 2. Phn b vi sinh vt trong nc 2.1 Ngun gc vi sinh vt trong nc Trong t nhin t khi c nc v trng. Ngun VSV trong nc t t, khng kh v cht thi, do nc trn b mt sng h, i ng cng cha VSV S tn ti pht trin ca vi sinh vt trong nc: nc l mi trng c coi l thch hp ca nhiu loi VSV, v nc c ch a y cc ch t h u c, khng kh v nhit thun li cho sinh trng pht trin ca VSV. - Nc trn b mt: nhiu cht hu c, nhit v thong kh tt, do VSV pht trin thun li, s lng v loi hnh kh ln. - Nc di su: t cha cht hu c, nhit lnh do qun th VSV y khng a dng, ch tn ti mt s nhm vi s lng nh hn nc b mt. - Vi sinh vt trong ao h - Vi sinh vt trong sng ngi - Vi sinh vt trong nc mch, nc ging, nc ma Vn lm nc sch: Nc dung thng b nhim bi cc VSV gy bnh xut pht t mt ngun gc l nc thi Bo v nc trnh nhim bi nc thi Cc bin php trnh nc b nhim - Xy dng cc trm x l nc thi loi tr cc vi sinh vt gy bnh.

- C s hng dn v quy nh cho c nhn, gia nh v cm dn c v s thot nc thi phi ng cch, ng ch trnh nhim vao nc dng ca chnh h. - Xy dng v xc nh cc ngun nc sinh hot phc v i sng dn c u gp phn phng nga s nhim ca nc. - Cc h cha nc thi c s chng thm tt phng nga ngm vo cc mch nc, ngun nc khc. - Phi c bin php trnh nhim cht thi vo b cha, ging nc b ng s d ng np y v lun lun kim tra loi tr tt c cc kh nng nhim nc thi. Bin php: - Lm lng - Lc nc: lc nhanh bng ct, lc chm bng ct - Kh trng: s dng Clo v hp cht c cha Clo, tia cc tm, dng ozon Xc nh gi tr ca nc: khng c hp cht hu c, khng c mi v l, khng c cc sn phm ha hc gy c, khng c VSV gy bnh. 3. Phn b vi sinh vt trong khng kh 3.1. S tn ti ca vi sinh vt trong khng kh Khng kh c coi l mi trng khng thun li cho s pht tri n c a VSV, thiu dinh dng, kh, lun b nh sng mt tri chi u sng v m a r a tri bi bn trong khng kh. 3.2. Bin php lm sch khng kh - Phng php lc: s dng cc vt liu, nguyn liu lc nh dng bng c tc dng gi VSV vi bi bn trong khng kh - Kh trng bng tc nhn vt l: dng n t ngoi kh trng khng kh trong phng m, phng th nghim VSV, phng ln men - Kh trng bng ha cht: xng phng bng hi foocmon pha trong thuc tm

Chng 7 Vi sinh vt ng dng trong trng trt v lm nghipI. 1. VI SINH VT T, CC NHM CHNH V C CH HOT NG

1. Nhng ging vi sinh vt quan trng thng gp trong t 1.1. Nhng ging vi khun thng gp trong t

Bng 2: Ging vi khun quan trng thng gp trong t

TT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Tn ging vi khun Chromatium

Nhng c im quan trng

Ym kh, mi trng giu cht hu c, c H2S Rhodospirilum Ym kh v ym kh ty tin, mi trng Rhodopeseudomanas giu cht hu c, c th quan hp c Nitrosomonas Hnh que, dinh dng ha nng, oxi ha Nitrobacter NH4+ thnh NO2 v NO3-, ho kh v ho kh ty tin Thiobacillus Hnh que dinh dng ha nng, oxi ha hp charat cha S hay cht kh cha S, ym kh ty tin Hidrogennomonas Hnh que,dinh dng ha nng, ly nng methanomonas lng t oxi ha hidrogen, oxi cacbon, metan Canlobacter Hnh que, Gram m, sng trong nc, ni Gallionella theo mt nc, bm vo tn d thc vt Siderocapsa Hnh que, hnh cu, hnh chy, l nh ng Ferribaterium vi khun chuyn ha st Pseudomonas Hnh que, hnh bu dc, thng sinh sn Acetobacter cc st t tan hoc khng tan trong nc. Virbro, Cellvibro Hnh xon, hnh du phy, ho kh hoc Spirillum ym kh, phn hy xenlulo, kh SO 42thnh H2S. Azotobacter, Hnh cu, hnh que, ho kh, c nh nit Rhizobium phn t t do hoc cng sinh Chromonobacterrium, Hnh que, hoi sinh hay k sinh, ym kh Agrobacter ty tin. Achromobacter, Hnh que, Gram m, khng sinh nha bo, Flavobacterrium ln men hidratcacbon, ho kh. Escherichia, Hnh que, Gram m, ho kh hoc ym Proteus, Aerobacter kh ty tin, ln men hidratcacbon. Micrococcus, Hnh cu, ho kh hoc ym kh ty loi, Sarcina Gram dng, khng sinh nha bo Brevibacterium Hnh que, Gram dng, ho kh, ym kh ty tin Streptorcocus, Hnh cu, hnh que, ym kh n vi ym Laetobacillus kh. Corynebacterium, Hnh que, hnh chui xon, Gram dng, Cellulomonas ho kh hoc ho kh ty tin. Clostridium, Hnh que, Gram dng, sinh nha bo, ho Bacillus kh, ym kh, c nh N 2, phn hy cc cht kh tan

1.2Nhng ging x khun quan trng thng gp trong t STT Tn ging x khun 1 2 3 4 5 6 Actinomyces, Bacterionema Actinoplanes, Amorphosporangium. Streptosporangium, Streptomyces Cellulomonas, Jonesia Dermatophilus Frankia Nhng c im quan trng Ho kh, hnh cnh cy, chn chim, phn hy, chuyn ha cht hu c Ho kh, hnh cnh cy hoc hnh rng lc, phn hy cht hu c Ho kh, hnh xon, rng lc, phn hy, chuyn ha cht hu c Ho kh, hnh xon, chm qu, phn hy chuyn ha cht hu c. Ho kh, hnh l da, chm qu, phn hy, cht hu c. Ho kh, hnh cnh cy, chn chim, phn hy, chuyn ha cht hu c.

1.3. Nhng ging nm quan trng thng gp trong t STT Tn ging nm 1 2 3 4 5 Zygomycetes Rhizopus Ascomyces Basidomycetes Penicilitum Nhng c im quan trng Sng hoi sinh, a m, giu hu c, ln men tinh bt. a m, giu cht hu c, phn hy c cht mnh, chu c nhit cao. a m, phn hy mnh c cht, chu c nhit cao. K sinh trn cy ha tho, phn hy mnh xenlulo, lignin. Bc cao, a m, phn hy mnh hp cht hu c.

1.1. Nhng ging to thng gp trong t STT Tn ging to Nhng c im quan trng 1 Cyanophyta to nc ngt, sn phm quan hp l lam glicogen, sng cng sinh vi bo hoa du,

2. Vi sinh trong qu trnh hnh thnh v kt cu mn 2.1.1 Quan im v qu trnh hnh thnh mn a)Theo quan im ha hc, th mn l cht trung gian, hay cht d tha cha c phn gii ht do cc phn ng ha hc trong t. b)Quan im sinh hc th mn khng phi l hp cht d th a, v l h p ch t d tha th khng bao gi c thnh phn v t l cc nguyn t , trong , l i nhiu hn cht ban u c vi vo t _ Mn khng phi l cht trung, v nu l cht trung gian th s m hay mu n cng b phn gii, nhng thc t lun lun dc tch ly. Mn l mt sn phm tng hp c hnh thnh nh vo hot ng s ng c a vi sinh vt. H cho rng ty tng chng ging vi sinh v t khc nhau c ch ho t ng khc nhau m to axit mn khc nhau. S chuyn ha cc cht hu c dc chuyn ha vi vo trong t di tc d ng ca vsv theo 2 hng sau: _ Qu trnh v c ha: l qu trnh chuy n ha cc h p ch t h u c thnh cc ch t v c d tiu. Nu qu trnh v c ha xy ra mnh. Cy trng khng ng ha ht, dn n s d tha gy c cho cy. _ Qu trnh mn ha: l qu trinh chuyn ha cc h p ch t h u c thnh cc ch t v c v hu c n gin hn kt hp vi qu trnh t tiu t gii ca vsv. 2.1.2 Khu vsv v s hnh thnh mn ca Konopva: Theo Konopva, th vsv phn hy xc ng, th c vt hnh thnh mn, g m 2 nhm tham gia: + Nhm vsv ln men, gm: vsv phn gii tinh bt , vsv ln men ng, vsv phn hy chuyn ha xenlulozo, hemixenlulozo, + Nhm vsv sinh tnh t l vsv phn h, chuy n ha cc ch t b n v ng nh : kitin, sp 2.2 Vi sinh vt yrong qu trnh cu to v kt cu mn: Vsv phn hy, chuyn ha cc hp cht c vng thm phc tp thnh cc dng quinol kt hp vi axit amin v polipeptit to ra nh ng sn ph m u tin ca axit mn. Qa trnh phn gii cc hp cht trong t, vsv hp th cc cht dinh dng. Trong qu trnh t tiu, t gii to thnh cc h p ch t mn ho t tnh, ch t ny gn cht cc ht t li vi nhau lm cho ht t ti xp. Hn n a xc c a vsv sau khi cht, chng kt hp vi mt s ch t trong qu trnh phn gi i t o thnh phc cht, phc cht ny tham gia tch cc vo thnh phn v k t c u mn. 3. Vi sinh vt phn gii v chuyn ha cacbon trong t. 3.1 Qu trnh phn gii xenlulozo 3.1.1 Qu trnh phn gii xenlulozo - mXenlulozo c cu to dng si

Cc loi VSV c kh nng phn gii xenlulozo: VSV ho kh (Nim vi khu n, vi khun, x khun, nm mc), VSV ym kh (vi khun d c), VSV y m kh s ng t do, VSV a nng. C ch ca qu trnh phn gii: mun phn gii c xenlulozo, cc loi VSV phi tit ra enzym xenlulaza. Enzym xenlulaza l enzym ngoi bo v c ch chung ca qu trnh phn gii xenlulozo l: Xenlulozo daccarit monosaccarit (glucozo) 3.1.2 Cc loi vsv phn gii xenlulozo C rt nhiu vsv phn gii xenlulozo: _ Vsv ho kh: Vi khun: cc ging Bacillus, ging Clostridium. X khun: Streptomyces. Nm mc:Aspergillus, Penicillium, Fusarium. _Vsv ym kh: Vi sinh vt d c: ging Ruminococcus _ Vi khun a nng: Bacillus cellulosae thermophicus. 3.1.3 C ch ca qu trnh phn gii Mun phn gii c xenlulozo, cc loi vsv phi tit ra enzim xenluloza. Enzim xenluloza l enzim ngoi bo l c ch chung ca qu trnh phn gii xenlulozo l: xenlulozo disaccarit monosaccarit (glucozo) 3.2 S phn gii xilan: Co ch phn gii: Di tc dng ca enzim xilanza ngoia5 bo, xilan s phn gi i thnh cc phn khc nhau: nhng on di xilanbiozo v xilozo. Mt s xilan c cha cc thnh ph n b sung khc: arabinozo, glucozo, galactozo, axit glucuronic. Cng thc chung ca xinlan l (C5H8O)n 3.3 Phn gii pectin Vi sinh vt phn gii pectin Bcillus nesenterricus, Bacillus maccaras, Bacillus ppomyxa C ch phn gii: Vi sinh vt phn gii pectin nh c enzim protopectinaza bin protopectin khng tan thnh pectin ha tan. Pectin ha tan l polysaccarit c to nn t cc gc axit .D.galacturonic 3.4 S phn gii lignin (liginine ) Vi sinh vt phn gii lginine Nm mc Basidomycetes c th chia lm 2 nhm. Mt nhm c th chuy n nhanh chng g thnh mt khi mu , ch yu l ph hy xenlulozo v hemyxenlulozo, khng c tc ng ln lignin. Mt nhm phn hy g thnh m t khi trng, chng ch yu tc ng ln lignin, hu nh khng lm phn gii

xenlulozo. Cc loi nm tc ng ln lignin: Polisitctus versicolor, pholiota, Lenzites Nhiu loi vi khun v x khun cng c kh nng phn gii ligin. Cc loi vi khun c hot tnh phn gii lignin cao thng thu c v cc gi ng Pseudomonas, Agrobacterium 4. Qu trnh tng hp v phn gii cc hp cht cha N2 Qu trnh amon ha 4.2.1 Qu trnh amon ha protein: + Di tc dng ca vsv, protein c phn gii cho NH 3 gi l qu trnh amon ha protein. + Vsv ch yu: c rt nhiu loi vsv c kh nng phn gii protein: vi khu n h o kh, ym kh, x khun, nm. + C ch phn gii: Di tc dng ca enzim proteaza, cc protein dc phn gi i thnh cc h p cht n gin hn. Cc cht ny c tip tc phn gi i thnh axit anim nh tc dng ca enzim peptidaza ngoi bo. Cc cht ny cng c th trc tip hp th vo t bo vsv, sau dc chuyn ha thnh axit amin. Cc axit amin ny s c s dng mt phn vo qu trnh sinh tng hp protein ca vsv, mt ph n c tip tc phn gii to ra NH3, CO2 v nhiu sn phm trung gian khc. 4.2.2 Qu trinh amon hoa ure, axit uric + ure: Ure l hp cht hu c n gin cha ti 46,6% N. Ure thng c trong nc tiu ng vt v ngi. Ure c th iu ch vi i u kin p sut 150- 200atm v nhit 150- 190C. NH3 + CO2 CO(NH2)2(ure ) Vi khun amon ha ure: Planosarcina ureae, Bachesmogenes Nhiu loi x khun v nm mc cng c kh nng phn gii ure. Vi khun ure thng thuc loi ho kh hoc k kh khng bt buc. Chng pht trin tt trong mi trng trung tnh hoc hi kim. Chng khng s dng c cacbon trong ure, ure ch dng lm ngun cung cp nito cho chng. Chng c enzim ureaza lm xc tac21 qu trnh phn gii ure thnh NH3, CO2, H2O. 4.2.3 Qu trnh amon ha kitin Vi sinh vt phn gii kitin: nhiu loi vsv c kh nng phn gi i kitin. ng ch l nhng loi thuc cc ging sau: Achromobacter, Bacillus, Penicillium. Qu trnh phn gii kitin c nghin cu k vi khun bacchitinovoium v x khun Streptomyces griseus. Chng c kh nng sinh ra ni bo. Kitinaza, Kitobioza. Kitinaza c tc dng ln cc phn khc nhau ca phn t kitin v phn gii thnh kitobio v kitotrio, kitoyrio sau s tip t c phn gi i thnh cc g c n phn t nh xc tc ca enzim kitobioza.

4.3 Qu trnh nitrat ha 4.3.1 nh ngha Di tc dng ca mt s loi vsv c bit, NH3 c hnh thnh do qu trnh amon ha hoc NH4+ cc loi phn ha hc s c tip tc chuyn ha thnh NH2- ri sau chuyn thnh NO3-, gi l qu trnh nitrat ha. 4.3.2 Vi sinh vt ch yu Qu trnh ny chia lm 2 giai on khc nhau do 2 loi vi khun dm nhim: + Giai on 1: giai on nitrit ha Vi khun tham gia vo giai on chuyn ha NH 3 thnh NO2- thuc v 4 ging khc: Nitrosomonas, Nitrocystis, Nitrosolobus, Nitrosospira. Enzim xc tc cho qu trnh oxy ha ny l enzim thng thng ca qu trnh h hp ho kh. + Giai on 2: giai on nitrat ha Vi khun tham gia vo giai on ny gm cc ging sau: Nitrobacter, Nitrospira, Nitrococcus. C ch ca qu trnh c biu th bng phng trnh sau: NO2- + 3/2O2 NO2+ H2O+ 2H+ nng lng Vi khun nitrat ha thuc loi t dng ha nng. 4.5 Qu trnh c dnh N2: 5.Tc dng ca vsv chuyn ha lu hunh trong t nhin 5.1 Chu trnh tun hon lu hunh Vng tun hon S v N c nhiu i ging nhau: + Trong t, N v S dng hu c l ch yu cho nn cy tr ng khng ng ha c. Mun ng ha phi c v c ha. +Qu trnh SO42- ha gn ging qu trng NO3- ha. + Qu trnh sunphat ha( hay cn gi l qu trnh v c ha S hu c) rt ging qu trnh amomn ha. Qu trnh kh SO4-2 rt gng qu trnh phn NO3- ho 5.2 V c ha lu hunh hu c Lu hunh hu c trong t thng 3 dng sau: _ Axit amin c S _ Sunfat hu c v este sunfuric ca hidratcacabon v lipit _ S hu c gn cht trong cc phn t axit humic v phn khong 5.3 Vi sinh vt phn gii lu hunh hu c v c ch phn gii _ Vi sinh vt: Froteus, Seratia, Microsporum 5.4 iu kin ngoi cnh nh hng n qu trnh phn gii lu hunh hu c m 40- 60%: nhit nh hn 10C xy ra yu, thng 25- 35C. S khong ha trong cht hu c ph thuc vo t l C/S l 112. 5.5 Qu trnh oxy ha hp cht lu hunh v c

Trong t nhin c mt s nhm vsv c th oxy ha hp ch t l u hunh v v c . Thng c 4 nhm vsv: + VSV ha nng dinh dng- ging Thiobacillus. + VSV ha nng hu c dinh dng (d dng ) + VSV ha nng dinh dng thuc h Beggiatoaces + VSV ha nng dinh dng: Chlro bacteriacees v Thiorhodacees 5.6. iu kin ngoi cnh nh hng n qu trnh oxy ha S t bo ha nc lm gim qu trnh oxy ha sinh hc S Nhit 4- 23C pH: 5,2 n 6,4- 7,5 5.7. Tc dng ca qu trnh oxy ha S + Thiobacillus c th oxi ha lu hunh thnh SO4. Mi trng tr nn chua. Do c th trung ha mt phn cht kim, tng cng cu trc t. + H2SO4 c hnh thnh trong qu trnh oxi ha S s lm tng tan ca mu i Ca3(PO4)2 kh tan, cung cp photphat monocanxi cho cy. + Qu trnh oxi ha lu hunh lm tng chua ca t, t mt s nguyn t t kh tan thnh d tan, v d nh Mn: Mn4+. + Qu trnh kh cc hp cht lu hunh v c. 6. Qu trnh chuyn ha photpho 6.1 Cc dng photpho (ln) v vng tun hon ca photpho 6.1.1 Ln hu c _Ln hu c c trong c th ng vt, thc vt, vsv th ng gp cc h p ch t ch yu nh phytin, photpholipit,axit nucleic. Trong khng bo ngi ta cn tm thy ln v c dng orthhophotphat lm nhim v dm v ch t d tr . Cy trng, vsv khng th trc tip ng ha ln hu c. Mun ng ha chng ph i c chuyn ha thnh dng mui ca H2PO4. 6.1.2 Ln v c Ln v c thng trong cc dng khong nh apatic, photphoric, photphat st, photphat nhm Mun cy trng s dng c phi qua ch bin, bin chng thnh dng d tan. 6.3 C ch ha tan Qu trnh phn gii photpho c biu din bng phng trnh sau: Ca3(PO4)2 + 4H2O + 4CO2 2Ca(HCO3)2 + Ca(H2PO4)2 Trong t vi khun nitat ha v vi khun chuyn ha S cng c tc d ng quan trng trong vic phn gii Ca3(PO4)2. Qu trtinh2 ha tan cc hp cht ln kh tan c th theo c ch : ln kh tan c tm thi ng ha bi vsv, s au ln c gii phng khi vsv di dng d tiu, m cy trng c th ng ha c. 6.4 S chuyn ha ln hu c Cc dng ln hu c thng gp trong t

Trong t cc dng ln hu c thng gp l: phytin, axit nucleic, photphollipit. a) Phytin v cc cht h hng Phytin l mui Ca v Mg ca axit phytic. Trong t nh ng ch t c h hng v i phytin l inositol, inositolmonophotphat, inositoltriphotphat. a) Axit nucleic v nucleoprotein Nhng axit nucleic v nucleoprotein u c ngun gc th c vt hoc ng v t v nht l vsv. Hm lng ca chng trtong t khong