Alignment of amino acid sequences deduced from the nifH sequence of Paenibacillus sp. and from the sequences of nifH genes of other organisms in the database. The sequences compared correspond to residues 48 to 155 of the Anabaena (Nostoc) sp. strain 7120 sequence (GenBank accession no. A00534). Abbreviations: av, Azotobacter vinelandii; kp, Klebsiella pneumoniae; C3l4, sd20, 2rc1, atcc, be1, rcpg7, and f102, P. azotofixans C3L4, SD20, 2RC1, ATCC 35681, BE1, RCPG7, and F102, respectively; rc, Rhodobacter capsulata; rm, Rhizobium meliloti; LL, Lyngbya lagerheimii; durum, P. durum; p3e20 and frbn4, P. azotofixans P3E20 and RBN4, respectively; cp3, C. pasteurianum nifH3 alternative (anf); cp1, C. pasteurianum nifH1; mtal, Methanococcus thermolithotrophicus alternative (anf); pol, P. polymyxa; mac, P. macerans. For database accession numbers see Fig. 3.