text: The genomes of Melainabacteria organisms isolated from ground water indicate that the organism has the capacity to fix nitrogen. Melainabacteria lack linked electron transport chains but have multiple methods to generate a membrane  potential which can then produce ATP via ATP synthase.  They are able to use Fe hydrogenases for  production that can be consumed by other  microorganisms. Melainabacteria from the human gut also synthesize several B and K vitamins, which suggests that these bacteria are beneficial to their host because they are consumed along with plant fibers.