Chair of Medical Biology, Microbiology,

Virology, and Immunology

CLASSIFICATION AND MORPHOLOGY

OF BACTERIA.

Lecturer As. Prof. O. Pokryshko

Bergey's Manual

of Determinative Bacteriology – the

"bible" of bacterial taxonomy.

There are such levels of

microorganisms’ organization:

Species – Genus – Family – Class –

Division – Kingdom

Classifications system.

35 of the major groups of bacteria are

distinguished primarily on morphological

characteristics, namely: cell shapes (rods,

cocci, curved, or filament forming); spore

production; staining reactions; motility.

Other groups are defined based on their

metabolism, or combinations of

morphological and physiological

characteristics.

Some of the Major Groups of Bacteria

in Bergey's Manual

Spirochetes

Very slender rods that are helically

coiled around a central axial filament;

includes the bacteria that cause

syphilis and Lyme disease

Gram-positive

cocci

Bacteria that have a cell wall structure

that results in their staining blue-

purple by the Gram stain procedure

and that are spherical; include the

streptococci and staphylococci

Endospore-forming rods and

cocci

Bacteria that form heat-resistant bodies

called endospores within their cells;

include the bacteria that cause gas

gangrene, botulism, tetanus, and

anthrax

� Small, single-celled (unicellular) organisms.

� Procaryotes: “Before nucleus”.

Lack the following structures:

�Nuclear membrane around DNA

�Membrane bound organelles

�Mitochondria

�Chloroplasts

�Golgi apparatus

�Endoplasmic reticulum

�Lysosomes

Bacteria (Sing. Bacterium)

Property Prokaryotic Eukaryotic

1- Size 0.5 - 10µm 5-100µm

2- Cell Wall Present in all bacteria

Except in Mycoplasma

Present in Fungi & Algae

3- Cytoplasmic

Membrane

No Sterol Except in

Mycoplasma

Has sterols

4- Nuclear

Membrane

Absent Present

5- Nucleus Absent Present

6- Chromosome Single chromosom

[not associtred with

protein

More than one

[associated with histone]

7- Mitochondria Absent Present

8- Ribosome Sedimentation coefficient

70S

Sedimentation coefficient

80S

9- Reproduction Asexual (binary fusion) Sexual & Asexual

10- Example Bacteria, Chlamydia,

Rickettsiae

Fungi & Protozoa

Bacterial Identification and

Classification

� Shape - cocci, bacilli, spiral

� Arrangement - single, pairs, chains,

clusters

� Size

� Gram-positive vs. Gram-negative

� Aerobic vs. anaerobic

� Physical/structural characteristics

� Biochemical characteristics

� DNA analysis

The Dimension of BacteriaThe Dimension of Bacteria

Relative size of a bacterial cell compared

to other cells including viruses.

Gross morphology of bacteria

� Size - 1 to 10 mm - aids in identification

� Shape

Coccus - round

Bacillus - rod

- Fusiform, coccobacilli

Spirillum - corkscrew

- Flexible, undulating - spirochetes

- Curved - vibrios

Cocci groupings

Coccus

Diplococcus

Streptococcus

Tetrad

Sarcinae

Staphylococcus

Chains of cocci

Streptococcus pyogenes

Clusters of cocci

Staphylococcus aureus Sputum smear

Bacillus shaped bacteria

Pseudomonas aeruginosa

Escherichia coli

Bacillus shaped bacteria

Fusobacterium

Bacillus chains

Bacillus anthracis

Palisades arrangement

Corynebacteriumdiphtheriae

Curved bacteria

Vibrio cholerae

Campylobacter

Curved bacteria

Borrelia burgdorferi

Spirilla