By Levi Clancy for Student Reader on
To isolate an aerobic N2 fixer, plate soil with a nitrogen sources (ammonia), O2 and carbon reducer. Incubate. Plate on NH3 agar, -NH3 agar, and MA. Our desired bacteria will grow on all but -NH3 agar. No eukaryotes aerobically fix N2. Azotobacter is an example of a nitrogen fixer. Ethylene is a nitrogenase substrate.