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Page 1: Bacteriology week3-4

BACTERIBACTERIOLOGIOLOGI BACTERIBACTERIOLOGIOLOGI

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Bacteria on Earth

Bacteria are in every environment imaginable!

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Size

Fig. 2-5 Six Comparisons Among Various Living Things and Molecules5/03/2012 3Masdiana Padaga

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Rod-Shaped Bacteria

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Spherical Bacteria

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Spiral-Shaped Bacteria

Spi

roch

ete:

Bor

relia

bur

gdor

feri

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Bacterial Morphology

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Bac

teria

l Ana

tom

y (O

verv

iew

)

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Prokaryotic Cells• Means “before a nucleus”

• Domains Bacteria and Archaea• Can live in environmental extremes

• Live off diverse energy sources

http://micro.magnet.fsu.edu/cells/bacteriacell.html http://www.daviddarling.info/encyclopedia/P/prokaryoticcell.html

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Prokaryotic Structures• Cytoplasm

– A liquid material that particles are suspended in

• Ribosomes– Site of protein synthesis– Located in cytoplasm

• Nucleoid– Contains hereditary

material (DNA) of the cell

– Located in cytoplasm5/03/2012 10Masdiana Padaga

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Prokaryotic Structures• Plasma membrane– Encloses the cell– Regulates material

into and out of cell

• Cell Wall– Supports cell and

determines its shape

• Capsule– Slime layer– Protects– Helps to not dry out– Helps attach to other

cells5/03/2012 11Masdiana Padaga

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Prokaryotic Structures• Flagella

– Used to swim/move– Spins like a

propeller or whip like

• Pilli– Hair or threadlike

structures– Help stick to other

cells for mating or animal cells for food and protection

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Cytoplasm • Composed largely of water, together with proteins,

nucleic acid, lipids and small amount of sugars and salts

• Ribosomes: numerous, 15-20nm in diameter with 70S; distributed throughout the cytoplasm; sensitive to streptomycin and erythromycin site of protein synthesis

Plasmids: extrachromosomal genetic elements

Inclusions: sources of stored energy, e,g volutin

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Plasmid Plasmids

are small , circular/line , extrachromosomal ,double-stranded DNA molecules 。

capable of self-replication and contain genes that confer some properties such as antibiotic resistance , virulence. Inclusions of Inclusions of

BacteriaBacteriaInclusions are aggregates

of various compounds that are normally involved in storing energy reserves or building blocks for the cell.

accumilate when a cell is grown in the presence of excess nutrients

granulose

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Cell membran

e

• Site of biosynthesis of DNA, cell wall polymers and membrane lipids. Selective permeability and transport of solutes into cells

• Electron transport and oxidative phosphorylation• Excretion of hydrolytic exoenzymes

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Nucleus

• Lacking nuclear membrane, absence of nucleoli, hence known as nucleic material or nucleoid, one to several per bacterium.

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Prokaryotic Cell Structure

Glycocalyx - term to describe substances that surround bacterial cells

1. Capsule if substance is organized and firmly

attached to cell wall 2. Slime Layer

if substance is unorganized and loosely attached to cell wall

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Capsules and slime layers

These are structures surrounding the outside of the cell envelope. They usually consist of polysaccharide; however, in certain bacilli they are composed of a polypeptide (polyglutamic acid). Capsules are often lost during in vitro culture.

Attachment Protection from phagocytic

engulfment. Resistance to drying. Depot for waste products. Reservoir for certain

nutrients. protection

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Polar monotrichousPseudomonas

Polar amphitrichousSpirillium Lophotrichous

Spirillum

PeritrichousSalmonella

Flagella:

SEM of peritrichous strain Proteous

Note: bacteria without flagella are called atrichous.5/03/2012 19Masdiana Padaga

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In Gram-negative Bacteria

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In Gram-positive Bacteria

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• Flagella consist of a number of proteins including flagellin

Identification of Bacteria

Pathogenesis Motility of bacteria

Motility• Almost all Spiral bacteria are

motile• About 1/2 of Bacilli are

motile• Almost all Cocci are non-

motile• Bacteria move toward

attractive stimuli and away from harmful substances and waste products in the process known as chemotaxis.

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Pilli or fimbrae• Filamentous appendages that are

shorter, straighter and more numerous that flagella

• Conjugation pilli found in certain group of bacteria.

• Used for genetic material transfer.

• The transfer process is called conjugation.

• Antibiotic resistance transfer.• Atatchment pilli, Help bacteria

adhare to the surfaces, such as cell surfaces and interface of water and air.

• It helps in colonization and pathogenicity.

• found mostly in Gram (-) Bacteria5/03/2012 24Masdiana Padaga

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E. coli (pathogenic)5/03/2012 25Masdiana Padaga

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Cell Wall• Main structural component -

Peptidoglycan

• Peptidoglycan– repeating dissacharide units– polypeptides

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Gram-Positive

Peptidoglycan

Cell Membrane

Peptidoglycan

Cytoplasmic membrane

Another cell

Gram-Negative

Outer Membrane

MembranePeptidoglycan

Peptidoglycan

Periplasm

Periplasmic space

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Bac

teria

l Cel

l Wal

ls

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Gram (+) Cell Wall• NAM N-acetylmuramic acid• NAG N- acetylglucosamine• tetrapeptide side chains• pentaglycine crossbridges• teichoic acid

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Gram (-) Cell Wall

• NAM• NAG• Tetrapeptide side chains• pentaglycine• 2nd Outer membrane

– Lipopolysaccharides (LPS)• Lipid A• O Antigen

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Functions of Cell Wall• Maintaining the cell's characteristic shape- the

rigid wall compensates for the flexibility of the phospholipid membrane and keeps the cell from assuming a spherical shape

• Countering the effects of osmotic pressure• Providing attachment sites for bacteriophages• Providing a rigid platform for surface

appendages- flagella, fimbriae, and pili all emanate from the wall and extend beyond it

• Play an essential role in cell division• Be the sites of major antigenic determinants

of the cell surface 。• Resistance of Antibiotics

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Cell Membrane (Plasma Membrane)

• 2 structural component– double layer of phospholipids– proteins

• Fluid Mosaic Model

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cytoplasmic membrane

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Functions of Cell Membrane

• 1. Selective barrier (selectively permeable)

• 2. Secretes exoenzymes– amylases– lipases– peptidases– CAN NOT UNDERGO PHAGOCYTOSIS

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Functions of Cell Membrane

• 3. E.T.S. is located here• 4. Enzymes for cell wall synthesis• 5. If photosynthesis, enzymes are

located on membranous structures called thylakoids

• 6. Mesosomes - invagination of cell membrane attached to DNA (Binary Fission)?

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Endospores (spores)

• Dormant cell Dormant cell • Resistant to adverse Resistant to adverse

conditions conditions - high temperatures- high temperatures- organic solvents- organic solvents

• Produced when starvedProduced when starved• Contain calcium dipicolinateContain calcium dipicolinate DPA, DPA, DDipicolinic acidipicolinic acid• BacillusBacillus and and ClostridiumClostridium

Identification of Bacteria

Pathogenesis Resistance

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Microscope • Light Microscope• Electron Microscope• Darkfield Microscope• Phase Contrast

Microscope• Fluorescence Microscope• Confocal Microscope )

Method

Staining Methods Simple staining; Differential staining (Gram

stain, Acid-fast stain), Special staining( Negative

stain, Spore stain, Flagella stain)

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Gram Stain• 1884 Hans Christian Gram• most important stain used in

Bacteriology

• Divides all Bacteria into 2 groups:– Gram (+)– Gram (-)

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Gram Staining

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Results• Gram (+) Purple• Gram (-) Red• Difference - due to

structure of cell wall– Gram (+) Thick cell wall– Gram (-) Thin cell wall

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