Fig. 2: Maximum-likelihood phylogenetic tree of non-redundant nitrogenase subunit NifH identified from cold seep metagenomic assemblies.
From: Phylogenetically and catabolically diverse diazotrophs reside in deep-sea cold seep sediments

Homologues of nifH were classified into canonical groups I to III, nitrogen fixation-like groups IV to VI, and newly assigned groups including groups of Methanosarcina-like, VII and VIII. NflH denotes NifH-like sequences. Scale bar indicates the mean number of substitutions per site.