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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
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