MbnC: the secondary Mbn biosynthesis gene. (A) MUSCLE alignment of MbnC putative biosynthesis proteins. The Group V sequences are divergent and not included. Residues are colored following the Taylor color scheme , with intensity modified by a conservation color increment of 30%. Truncated metagenomic sequences are not shown in this alignment. (B) Phylogenetic tree (constructed in MEGA 5.0 as described in the Methods section) based on a MUSCLE alignment of all MbnC sequences, not including truncated metagenomic sequences. Gamma distribution parameter 2.1637.