Question

A bacterium, which is capable of utilising the most abundantly available gas in the atmosphere for one of its metabolic pathways, but cannot utilise the second abundantly available gas for its another metabolic pathway, is

• A. Azotobactor
• B. Clostridium
• C. Rhodomicrobium
• D. Xanthomonas

Answer 1

The correct option is B Clostridium

Clostridium is an anaerobic bacterium. The bacterium is a free-living nitrogen fixer. The atmospheric nitrogen (N${}_2$) is converted to nitrates which can be utilised by the plants. The bacterium is an obligate anaerobe and so cannot survive or utilise the oxygen which is available in the environment.

Thus, the correct answer is option B.