$Rhodospirillum$ is an anaerobic free-living bacterium.

What is nitrogen fixation?

Which of the following organisms fixes atmospheric nitrogen in a free-living state?

The most active nitrogen-fixing blue-green alga in rice fields is:

For its action,nitrogenase requires

How many of the following organisms are capable of nitrogen fixation?
Azospirillum, Glomus, Nostoc, Monascus purpureus, Yeast, Anabaena, Oscillatoria, Azotobacter, Trichoderma