The family Enterobacteriaceae is a very large group of gran negative bacteria that posses a number of common morphological and biochemical properties and similar DNA base compositions.
The widely used systems for the classification of enterobacteriaceae are
Even having certain differences, the general approach is same.
The family is a group of subdivision or tribes and each tribe consists of one or more genera.Similarly, each genus consists of one or more sub genera and species. The species are classified into types like biotypes, serotypes, bacteriophage types and colicin types.
This family has following tribes
Tribe 1: Escherichiae
Tribe 2: Klebsiellae
Tribe 3: Proteeae
Tribe 4: Erwinieae
The family enterobacteriaceae has following general phenotypic features-
1. They are small gram negative rod
2. Having usual cell structure (non sporulated)
3. Motile by peritrichous flagella.
4. Grow on ordinary medium.
5. Grow both aerobically and anaerobically.
6. Grow without addition of sodium chloride or other supplements.
7. Grow well on MacConkey agar.
8. Active biochemically.
9. Ferments D-glucose and other sugar, often with gas production.
10. Catalase test positive.
11. Oxidase test negative.
12. Reduce nitrate to nitrite
13. Contain the enterobacterial common antigen (ECA) and
14. They have a 39-59% guanine plus cytosine (G+C) content of DNA.
All the members of family enterobacteriaceae are catalase positive except Shigella dysentery type 1.
All the members of family enterobacteriaceae are oxidase negative except Plesiomonas shigelloides which is oxidase test positive.
All oxidase positive bacteria are catalase test positive except Kingella, Eikenella and Cardiobacterium those are catalase test negative.
1. Topley Wilson ‘s Microbiology of Microbial infectious Bacteriology-2
2. Bailey & Scott’s Diagnostic Microbiology
Thirteen 13 Edition
3. Textbook of Practical Microbiology
Subhash Chandra Parija
This is the short explanation of family Enterobacteriaceae introduction and Phenotypic features.
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