Claim: Nif gene are genes encoding enzymes involved in the fixation of atmospheric nitrogen into a form of nitrogen available to organisms and are found in both free-living nitrogen-fixing bacteria and in symbiotic bacteria associated with various plants.
Evidence: The nif genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen into a form of nitrogen available to living organisms. The nif genes are found in both free-living nitrogen-fixing bacteria and in symbiotic bacteria associated with various plants.