Nitric Oxide Dismutase () Genes as a Functional Marker for the Diversity and Phylogeny of Methane-Driven Oxygenic Denitrifiers.

Oxygenic denitrification represents a new route in reductive nitrogen turnover which differs from canonical denitrification in how nitric oxide (NO) is transformed into dinitrogen gas. Instead of NO reduction via NO to N, NO is proposed to be directly disproportionated into N and O in oxygenic denitrification, catalyzed by the putative NO dismutase (Nod). Although a high diversity of genes has been recovered from various environments, still little is known about the niche partitioning and ecophysiology of oxygenic denitrifiers. One constraint is that as a functional marker for oxygenic denitrifiers is not well established. To address this issue, we compared the diversity and phylogeny of , 16S rRNA and gene sequences of four NC10 enrichments that are capable of methane-driven oxygenic denitrification and one environmental sample. The phylogenies of , 16S rRNA and genes of these cultures were generally congruent. The diversity of NC10 bacteria inferred from different genes was also similar in each sample. A new set of NC10-specific primers was developed and used in qPCR. The abundance of NC10 bacteria inferred from genes was constantly lower than via 16S rRNA genes, but the difference was within one order of magnitude. These results suggest that is a suitable molecular marker for studying the diversity and phylogeny of methane-driven oxygenic denitrifiers, the further investigation of which may be of value to develop enhanced strategies for sustainable nitrogen or methane removal.