Explain the role of microbes in nitrogen fixation.

There are some nitrogen fixing bacteria which live in close association with the plants in their roots as nodules. Both the bacteria and the plant are capable of independent existence but live with each other for a mutually beneficial association. The bacteria covert atmospheric nitrogen into ammonia which can be absorbed by the plant to be utilized. These bacteria  are known as rhizobia or symbiotic bacteria.
Non-symbiotic bacteria recognized in fixing nitrogen are- Cyanobacteria, Anabaena, Nostoc etc. 
Hence, bacteria plays a crucial role in nitrogen fixation.
Other microbes involved in the process of nitrogen fixation are fungi, which along with bacteria help in degradation of organic matter. It leads to a release of fixed nitrogen which can be reused by other organisms present.

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