Problem
A. Observe differences between cultures enriched for nitrogen fixers and those grown with ammonia. (flasks) Do you observe a film of surface growth? (describe)
B. What did you see when you stained the material from the flasks? (describe)
C. What was observed on the streak plates of mannitol cultures? (How many restreaks were necessary to achieve uniform colonies on the plate?)
D. There are also symbiotic nitrogen fixers in the environment. We would normally isolate these types of bacteria on a TSA (Trypticase Soy agar) plate instead of the Mannitol agar we used for Azotobacter. Explain why this is necessary.