This document summarizes the major divisions of the microbial world, including: 1) Ordinary gram-negative bacteria such as Pseudomonas, Shigella, and Salmonella that are aerobic rods and cocci or facultatively anaerobic rods. 2) Spirochetes like Treponema, Borrelia, and Leptospira that are flexible, helical bacteria with periplasmic flagella. 3) Other divisions include anaerobic gram-negative bacteria, sulfate-reducing bacteria, rickettsias and chlamydias, mycoplasmas, and endosymbionts.

1. MAJOR DIVISIONS OF
MICROBIAL WORLD
By
Nayakanti Bhasker Babu
Research Scholar
CES College of Pharmacy, Kurnool
ANDHRAPRADESH

3. THE WORLD OF BACTERIA I:
ORDINARY GRAM NEGATIVE BACTERIA

4. THE SPIROCHETES
• Flexible, Helical, Periplasmic flagella, Saprophytes or parasites Ex: Treponema,
Borrelia, Leptospira

5. AEROBIC/ MICROAEROPHILIC, MOTILE, HELICAL/VIBRIOD, GRAM-NEGATIVE
• Rigid; motile by polar flagella, oxidative type of metabolism, saprophytes or
parasites Ex: Azospirillum

6. NONMOTILE (RARELY MOTILE), GRAM-NEGATIVE,CURVED BACTERIA
• Rigid; curved, ring-shaped or helical cells lacking flagella; Saprophytes
Ex: Spirosoma, Runella, Flectobacillus

7. AEROBIC GRAM NEGATIVE RODS AND COCCI
• Rigid; Straight or slightly curved (but not helical) rods, cocci; oxidative type of
metabolism; saprophytes and parasites Ex: Pseudomonas

8. FACULTATIVELY ANAEROBIC GRAM – NEGATIVE RODS
• Rigid; straight or curved rods; have both oxidative and fermentative type of
metabolism; saprophytes and parasites Ex: Shigella, Salmonella, Enterobacter

9. ANAEROBIC GRAM-NEGATIVE STRAIGHT, CURVED AND HELICAL RODS
• Rigid ; obtain energy by fermentation or by an anaerobic respiration that does nor
use sulfur compounds as electron acceptors; parasites Ex: Bacteroids fragilis

10. DISSIMILATORY SULFATE OR SULFUR REDUCING BACTERIA
• Rigid; anaerobic; use sulfur compounds as electron acceptors; saprophytes an
parasites Ex:Desulfococcus

11. ANEAROBIC GRAM-NEGATIVE COCCI
• Rigid; nonmotile; fermentative; parasites Ex: Veillonella

12. THE RICKETTSIAS AND CHLAMYDIAS
• Rigid; tiny cells; intracellular parasites of humans, other animals and arthropods, can
be isolated and cultivated in host cells and sometimes on culture media
• Ex: Coxiella

13. THE MYCOPLASMAS
• Soft and plastic; nonmotile; lack cell walls; parasites and saprophytes Ex:
Mycoplasma pneumoniae

14. ENDOSYMBIONTS
• Bacteria – like forms that are obligate parasites of protozoa, arthropods or other
hosts; often beneficial to their hosts; have not been isolated or cultivated
• Ex: Lyticum flagellatum