title: Anaerobic carbon monoxide dehydrogenase diversity in the homoacetogenic hindgut microbial communities of lower termites and the wood roach.
abstract: Anaerobic carbon monoxide dehydrogenase (CODH) is a key enzyme in the Wood-Ljungdahl (acetyl-CoA) pathway for acetogenesis performed by homoacetogenic bacteria. Acetate generated by gut bacteria via the acetyl-CoA pathway provides considerable nutrition to wood-feeding dictyopteran insects making CODH important to the obligate mutualism occurring between termites and their hindgut microbiota. To investigate CODH diversity in insect gut communities, we developed the first degenerate primers designed to amplify cooS genes, which encode the catalytic (β) subunit of anaerobic CODH enzyme complexes. These primers target over 68 million combinations of potential forward and reverse cooS primer-binding sequences. We used the primers to identify cooS genes in bacterial isolates from the hindgut of a phylogenetically lower termite and to sample cooS diversity present in a variety of insect hindgut microbial communities including those of three phylogenetically-lower termites, Zootermopsis nevadensis, Reticulitermes hesperus, and Incisitermes minor, a wood-feeding cockroach, Cryptocercus punctulatus, and an omnivorous cockroach, Periplaneta americana. In total, we sequenced and analyzed 151 different cooS genes. These genes encode proteins that group within one of three highly divergent CODH phylogenetic clades. Each insect gut community contained CODH variants from all three of these clades. The patterns of CODH diversity in these communities likely reflect differences in enzyme or physiological function, and suggest that a diversity of microbial species participate in homoacetogenesis in these communities.
authors.affiliation: Ronald and Maxine Linde Center for Global Environmental Science, California Institute of Technology, Pasadena, California, United States of America. ematson@caltech.edu
authors.forename: Eric G
authors.initials: EG
authors.lastname: Matson
authors.forename: Kasia G
authors.initials: KG
authors.lastname: Gora
authors.forename: Jared R
authors.initials: JR
authors.lastname: Leadbetter
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000235:genetics*; D000693:Anaerobiosis / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D003058:Cockroaches / Q000382:microbiology*; D017931:DNA Primers / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D041981:Gastrointestinal Tract / Q000382:microbiology*; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation; D020049:Isoptera / Q000382:microbiology*; D054892:Metagenome / Q000235:genetics*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D010802:Phylogeny; D014934:Wood
chemical_list: D000085:Acetates; D017931:DNA Primers; D004269:DNA, Bacterial; D009097:Multienzyme Complexes; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase