Which among the following is a free living anaerobic nitrogen fixing bacterium ?

Rhizobium Clostridium Azotobacter Streptococcus

Clostridium

Nitrogen-fixing bacteria are those bacteria which fixes atmospheric nitrogen and make it available for the plants. There are 2 types of nitrogen-fixing bacteria, free-living (nonsymbiotic) bacteria and non free living (symbiotic) bacteria. Examples of free-living bacteria includes , cyanobacteria like Anabaena and Nostoc, Azotobacter, Clostridium. Out of these examples, Azotobacter is aerobic bacterium and Clostridium is anaerobic bacterium.