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  • Eleanor Jameson
    Gibbet Hill CampusThe University of Warwick
  • Andrew C Doxey
    Waterloo University
  • Ruth Airs
    Prospect Pl
  • Kevin J Purdy
    The University of Warwick
  • J Colin Murrell
    4​University of East Anglia
  • Yin Chen
    The University of Warwick

Existing metagenome datasets from many different environments contain untapped potential for understanding metabolic pathways and their biological impact. Our interest lies in the formation of trimethylamine (TMA), a key metabolite in both human health and climate change. Here, we focus on bacterial degradation pathways for choline, carnitine, glycine betaine and trimethylamine N-oxide (TMAO) to TMA in human gut and marine metagenomes. We found the TMAO reductase pathway was the most prevalent pathway in both environments. Proteobacteria were found to contribute the majority of the TMAO reductase pathway sequences, except in the stressed gut, where Actinobacteria dominated. Interestingly, in the human gut metagenomes, a high proportion of the Proteobacteria hits were accounted for by the genera Klebsiella and Escherichia. Furthermore Klebsiella and Escherichia harboured three of the four potential TMA-production pathways (choline, carnitine and TMAO), suggesting they have a key role in TMA cycling in the human gut. In addition to the intensive TMAO-TMA cycling in the marine environment, our data suggest that carnitine-to-TMA transformation plays an overlooked role in aerobic marine surface waters, whereas choline-to-TMA transformation is important in anaerobic marine sediments. Our study provides new insights into the potential key microbes and metabolic pathways for TMA formation in two contrasting environments.

Keywords

  • Actinobacteria/enzymology, Data Mining, Ecosystem, Gastrointestinal Microbiome/genetics, Geologic Sediments/microbiology, Humans, Metagenomics, Methylamines/metabolism, Oxidoreductases, N-Demethylating/genetics, Proteobacteria/enzymology
Original languageEnglish
Article numbere000080
JournalMicrobial Genomics
Volume2
Issue number9
DOIs
Publication statusPublished - 1 Sept 2016
Externally publishedYes
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