The nitrite forming bacteria are called "nitrosobacteria" while the nitrate forming, group is referred to as the 'nitrobacteria". The nitrifying bacteria form a small group consisting of 8 genera.
| Nitrosobacteria |
Nitrobacteria |
| Nitrite forming bacteria |
Nitrate forming bacteria |
| Ammonia oxidizers |
Nitrite oxidizers |
| Nitrosomonas |
Nitrobacter |
| Nitrosopira |
Nitrospina |
| Nitrosolobus |
Nitrococcus |
| Nitrosovibrio |
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The nitrifying bacteria are small, gram-negative, rod shaped or spherical bacteria. They arc slow growing bacteria, with generation time of about 10-12 hours.
They arc obligate autotrophs which cannot develop in the absence of the specific inorganic energy source. The exception to this rule are some strains of Nitrobacter which can use acetate, as the carbon and energy source. The strains, however, grow much more slowly with acetate than with nitrite.
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