Anthrax Bacillus anthracis

Cutaneous

anthrax

M A T A K U L I A H M I K R O B I O L O G I

E V I R O V I A T I

STRUKTUR SEL BAKTERI

Prokaryotes

Domains

Bacteria &

Archaea

Simple cells –

with no nucleus

or membrane-

bound

organelles

I. Bacteria Classification: Cell shape

A. Compound Light Microscope (1000X) - stained

Cocci (Coccus) Bacilli (Bacillus) Spirilli (Spirillum)

round or oval rod-shaped helically coiled

B. Scanning Electrom Microscope (SEM) - colorized

II. Classification Bacteria: Cell arrangement

1. Diplococcus (diplo=pairs)

Neisseria gonorrhoeae - Gram-negative,

causes gonorrhea

SEMStained: Compound Microscope

1000X

Staphylococcus aureus

Staphylococcus aureus - Causes food poisoning, toxic shock syndromeand skin and wound infections such as scalded skin syndrome, scarlet fever, and impetigo.

Stained: Compound Microscope

1000X

SEM (colorized)

2. staphylococcus (staphylo- grapelike clusters)

3. streptococcus (strepto=chains)

Streptococcus pyogenes

Stained: Compound Microscope

1000XSEM (colorized)

4. Streptobacillus

Bacteria

Structure

Cell wall – unique, peptidoglycan

Peptidoglycan - structural

polysaccharides

(sugars) cross-linked by

peptides (chains of amino

acids)

The Gram stain procedure

Developed in 1884 by the Danish physician

Hans Christian Gram

An important tool in bacterial taxonomy,

distinguishing so-called Gram-positive

bacteria, which remain coloured after the

staining procedure, from Gram-negative

bacteria, which do not retain dye and need to

be counter-stained.

Can be applied to pure cultures of bacteria

or to clinical specimens

Top: Pure culture of E. coli

(Gram-negative rods)

Bottom: Neisseria gonorrhoeae in a smear of urethral pus

(Gram-negative cocci, with pus cells)

Crystal violet

Gram's iodine

Decolorise with acetone

Counterstain withe.g. methyl red

Gram-positives appear purple

Gram-negatives

appear pink

The Gram Stain

Gram-positive rods

Gram-negative rods

Gram-positive cocci

Gram-negative cocci

Gram stainDistinguishes different cell wall types

Gram positive Staphylococcus aureus

Gram negative Escherichia coli

16

Be able to identify all the parts of a Gram + & - cell wall for the next exam.

Two biochemical groups of bacteria:

peptidoglycanouter

membrane

will stain will not stain

Gram positive bacteria Gram negative bacteria

Two biochemical groups of bacteria:

peptidoglycanouter

membrane

Bacteria with Chemically Unique Cell Walls

Acid-Fast Cells

Mycobacterium species

Gram + type of cell wall

Unique lipid

Mycolic acid – waxy substance

Does not decolorize

Bacterial Growth

Solid media or liquid media

Agar plates, slopes, broth culture

Atmosphere:

Aerobic, anaerobic or microaerophilic

Facultative or obligate anaerobes

Usually at 37 degrees C

Most clinically important bacteria grow overnight, or within a few days

Mycobacteria can take months

Some can not be grown

Capsules or slime layer

E.g., slime layer allows bacteria to

cling to tooth enamel or other

substrates

Pili (singular: pilus)Protein filaments that attach bacteria to other cells

& substrates

pili

Used for locomotion

Some prokaryotes have flagella(singular: flagellum)

flagella

50 nm

Base of a bacterial flagellum…

…the only known wheel in nature

Reproduction: Asexual, through binary fission

E. coli

DNA

cell wall

Binary fissionDaughter cells are identical copies

(1) (2) (3)

(4) (5) (6)

Chromosome Plasma membrane

Neither mitosis nor meiosis occurs in prokaryotes

REPRODUCTION

Asexual, through binary fission

No true sexual reproduction, since neither

mitosis nor meiosis exist in prokaryotes

Horizontal transfer of genetic material

Transformation Uptake of genetic material from the

environment

Transduction Transfer of genetic material between

prokaryotes by viruses

Conjugation Direct transfer of genetic material from one

prokaryote to another

Conjugation in E. coli

Sex pilus

Sex pilus connects cells and draws them together

Conjugation tube then forms

Bacteria

Surviving harsh conditions

Endospore – forms inside a bacterium and then persists

through inhospitable conditions

endospore

The oldest known fossils

First organisms

on Earth

Cyanobacteria

> 3 billion years

old

Distributed globally – including many

extremophiles

“Heat-loving”

Archaea

“Salt-loving”

Archaea

Methanogens

Methane-generating Archaea

Occur in oxygen-free habitats

E.g., swamp mud, guts of

ruminant animals

Cave Bacteria

Sometimes reaching

acidity of pH 0.5

Distributed globally – including many

extremophiles

Ice Bacteria & Archaea

Distributed globally – including many extremophiles

Prokaryote Nutrition – autotrophs & heterotrophs

All organisms require a source of energy & carbon

Autotrophs can

obtain all their

C from CO2

All organisms require a source of energy & carbon

Heterotrophs

require at least

one organic

nutrient, e.g.,

glucose

Prokaryote Nutrition – autotrophs & heterotrophs

All organisms require a source of energy & carbon

Phototrophs

obtain their

energy from

the sun

Prokaryote Nutrition – autotrophs & heterotrophs

All organisms require a source of energy & carbon

Chemotrophs

obtain their

energy from

chemical

compounds

Prokaryote Nutrition – autotrophs & heterotrophs

KLASIFIKASI BAKTERI