Identify the free living and anaerobic nitrogen fixer.
Rhodospirillum is anaerobic and free-living nitrogen fixer.
Azotobacter and Beijerinckia are free-living nitrogen-fixing aerobic microbes.
Cyanobacteria such as Anabaena and Nostoc are also free-living nitrogen-fixers. The cells of Anabaena and Nostoc shows metabolic compartmentalization only at the site where the enzyme nitrogenase is present.