Comparison of Paenibacillus polymyxa CR1 nif cluster to other free-living diazotrophic bacteria. Genes indicated by the same colour represent functional or structural homologs. Cluster homology is based off of gene clustering using available tools on the JGI Integrated Microbial Genomics Database. Representative nif clusters encoded by other free-living diazotrophic bacteria are included for comparison. Bacteria from Rhizobia are excluded due to the relative complexity of their nitrogen fixation clusters gene organization, as well as their requirement for nodulation, a trait not observed in Paenibacillus sp.