5/26/2018 Aflatoxin b1 Adsorption by Yeast Cell Wall
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P-97 Aflatoxin B1adsorption by yeast cell wall from commercial
origin
Kelly Moura Keller, Tatiana Xavier de Almeida, Rosane Nora
Castro, Carina M.Pereyra, Ana Mara Dalcero, Lilia Rene Cavaglieri,
Carlos Alberto da Rocha Rosa*(Argentina, Brazil).
1Departamento de Microbiologia e Imunologa Veterinria.
Universidade Federal Rural do Rio de Janeiro.
Instituto de Veterinria. Rio de Janeiro. Brazil.2Departamento de
Qmica - Universidade Federal Rural do Rio de
Janeiro. Instituto de Veterinria. Rio de Janeiro.
Brazil.3Departamento de Microbiologa e Inmunologa.
Universidad Nacional de Ro Cuarto. Ruta 36 km. 601. (5800). Ro
Cuarto, Crdoba. Argentina.
*Tel: ++5521 86048642 e-Mail: [email protected]
Background.Among more than 300 mycotoxins described as yet,
aflatoxin B1 (AFB1) andthe group of fumonisins (FBs) are the toxins
of major concern in tropical and sub-tropicalregions. Aflatoxins
are toxic secondary metabolites produced by species
ofAspergillusgenus,mainly A. flavus and A. parasiticusand its
effects are carcinogenic, mutagenic, teratogenicand hepatoxic.
Aflatoxin B1 is one of the most potent known hepatocarcinogens.
Mycotoxincontamination of feed is a serious problem because they
reduce feed consumption, decrease
growth rate and reduce immunity.Besides the health aspects,
which involves the presence oftoxins or toxic metabolic products in
food and / or by-products such as meat intended forhuman
consumption, its presence in animal feed has also important
economic connotationscausing losses by increasing mortality and
production (Rosa et al., 2001, 2006). One of themost effective
methods to control risks of mycotoxins in animal husbandry is based
on theuse of specific materials that adsorb mycotoxins. These
substances adsorb the toxins in thegastrointestinal tract to form
insoluble complexes that are eliminated in the feces. Thus,
thetoxic effects are diminished by reducing the bioavailability of
mycotoxins. In particular, the use
yeast cell -glucans and mannans- walls (PL), mainly composed of
oligosaccharides. Theyare usually introduced as a food additive in
the animal production industry since the 90s.
Objective. To evaluate the efficacy of a commercial yeast cell
wall to adsorb AFB1.
Materials and methods. Adsorbent:a yeast wall of commercial
origin (Safmannan - Safdo Brasil - Agricultural Division) was
resuspended in buffer at pH 2. pH 2 buffer solution:50mL of a
solution of potassium chloride (KCl) 0.2 M was added 13 mL of a
solution ofhydrochloric acid (HCl) 0.2 M. Aflatoxin B1 Solution: 10
mg of AFB1 (Sigma) wereresuspended in methanol (MeOH) to obtain a
solution of 2 mg/mL. From this, the toxin wasdiluted to obtain the
required concentrations for each test. Adsorption test:to determine
thepotential adsorption, saturation isotherms were previously made
with different concentrationsof the mycotoxin (250, 200, 100, 50,
10, 5, 2, 1 and 0, 1 mg/ml). Then, adsorption isothermswere made
between the PL (2 mg/ml) with AFB1(15,346, 10:33, 7:34, 2:08 and
4.83 mg/ml).Tests were assayed at pH 2 and 6, in triplicate. All
mycotoxin concentrations were evaluated
using high performance liquid chromatography (HPLC).
Results and Discussion. Figures 1 and 2 show the adsorption
isotherms at pH 2 and 6,respectively. Visual inspection shows a
S-type isotherm, following a Hill model that explainsthe
cooperative adsorption isotherm between the toxin and the
adsorbent. The mathematicalexpression of the adj max[ZEA]
n/kDn
adsorbed ZEA by g of PL, n the number of sites and kDconstant
adsorption site.
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5/26/2018 Aflatoxin b1 Adsorption by Yeast Cell Wall
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0 2 4 6 8
0,0
0,2
0,4
0,6
0,8
1,0
AFB1eq/ M
0 2 4 6 8
0,0
0,2
0,4
0,6
0,8
AFB1eq/ M Figure 1.Adsorption isotherm of AFB1by Safmannan
, (a) pH 2, (b) pH 6.Among the most important parameters we
consider a saturation value of 0.918 0.056 mg ofadsorbed AFB1/g PL
at pH 2 and 1.002 0.089 mg of adsorbed AFB1/g PL at pH 6.
Theassociation constant per site was 0.233 0.044 and 0.208 0.063
ng/mL-1 (Table 1).Table 1. Setting parameters obtained by Hill
model to evaluate the adsorption isotherms fromAFB1and Safmannanat
different pH.
Adsorbent ppH kd(M) max(g/g) n N RR2
D2,0 4,2910,189 0,2330,044 0,9180,056 3,8290,453 5
00,996Safmannan
S6,0 4,8060,303 0,2080,063 1,0020,089 3,6190,459 5 00,996
kd = dissociation constant, = association constant, max =
masimum capacity of adsorption, n = number of sites for
coorperativism, N = number of curve points. Each point is the
mean of triplicates.
Conclusion. Aflatoxin B1 was efficiently bound by PL through a
cooperative attractionmechanism. This result shows the potential of
this PL to prevent the toxic effects caused bythe intake of
ZEA.
References.
1. Hooge, D.M. (2004), Meta-analysis of broilen chicken pen
trials evaluating dietary mannanoligosaccharides 1993-2003, Int. J.
Poult .Sci. 3, 163-174.2. Newman, K. (1998). The biochemistry
behind esterified glucomannans titrating mycotoxins
out of the diet. En: Biotechnology in the feed Industry,
Proceedings of Alltechs 14thAnnual symposium. Nottingham University
Press, UK, p. 369.
3. Oliveira, G.R.; Ribeiro, J.M.; Fraga, M.E.; Cavaglieri, L.R.;
Direito, G.M.; Keller, K.M.;Dalcero, A.M.; Rosa, C.A.R. (2006)
Mycobiota in poultry feeds and natural occurrence ofaflatoxins,
fumonisins and zearalenone in the Rio de Janeiro State, Brazil.
Mycopathologia162, 355-362.
4. Rosa, C.A.R.; Miazzo, R.; Magnoli, C.; Salvano, M.;
Chiacchiera, S.M.; Ferrero, S.;Carvalho, E.Q.; Dalcero, A.M. (2001)
Evaluation of the efficacy of bentonite from south ofArgentina to
ameliorate the toxic effects of aflatoxins in broilers. Poultry
Sci. 80, 139-144.
5. Rosa, C.A.R.; Ribeiro, J.M.; Cavaglieri, L.R.; Fraga, M.E.;
Gatti, M.J.; Magnoli, C.;Dalcero, A.M. (2006) Mycoflora of poultry
feed and ochratoxin producing ability of isolatedAspergillusand
Penicilliumspecies. Veterinary Microbiology 113, 89-96.
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