Major groups of bacteria –

medical and industrial importance

 

Gram negative group

  1. Spirochetes
  2. Straight and curved rods and cocci
  3. Special Groups

 

1. Spirochetes (Family Spirochaeteae)

General characteristics

Important genera and species

Cristispira

Spirochaeta

Treponema

Borrelia

B. burgdorferi - Lyme disease

Leptospira

 

2. Straight and curved rods and cocci

(a) Spiral Cells (Spirilla)

General characteristics

Important genera and species

Spirillum

Aquaspirillum

Azospirillum

 

(b) Curved cells

General characteristics

Important genera and species

Campylobacter

C. fetus - abortion in sheep and cattle

Helicobacter

Bdellovibrio

 

(c) Aerobic rods and cocci

Important genera and species

i. Highly oxidative

Pseudomonas

Xanthomonas

ii. Nitrogen fixers

Rhizobium

Azotobacter

iii. Acetate producers

Acetobacter

Gluconobacter

iv. Pathogens

Legionella

Neisseria

Brucella

Bordetella

Francisella

v. Methylotrophs

Methylococcus: cocci

 

(d) Facultative Anaerobic Bacteria

i. Enterobacteriaceae

General characteristics

Important genera and species

Salmonella

i. gastroenteritis (S.enteritis)

ii. septicemia (S.cholerasuis, S.typhi, S.paratyphi)

iii. enteric fever (S.typhi- typhoid fever,

S.paratyphi- paratyphoid fever)

iv. asymptomatic carriage

Shigella

Escherichia

i. septicemia

ii. urinary tract infection

iii. meningitis

iv. gastroenteritis: enterotoxigenic or enteroinvasive

Klebsiella

Serratia

Proteus

Erwinia

Plant pathogens

ii. Vibrionaceae

General characteristics

Important genera and species

Vibrio

transmitted mainly by water contaminated with human faeces

after infection secretes an enterotoxin causing severe diarrhea

Aeromonas

Photobacterium

ii. Pasteurellaceae

General characteristics

Pasteurella

Haemophilus

Yersinia

bubonic and pneumonic plague (black death)

 

(e) Obligate Anaerobic Bacteria

Important genera and species

Bacteroidaceae

Bacteroides

Veillonella

Sulfate-reducing Bacteria

Desulfovibrio and Desulfuromonas

 

3. Special groups

  1. Rickettsias and Chlamydias

Rickettsias

Chlamydias

 

  1. Anoxygenic phototrophic bacteria

Purple and green bacteria

 

  1. Oxygenic phototrophic bacteria

Cyanobacteria

 

  1. Gliding bacteria

 

  1. Chemolithotrophs