title: Investigation of the microbial metabolism of carbon dioxide and hydrogen in the kangaroo foregut by stable isotope probing.
abstract: Kangaroos ferment forage material in an enlarged forestomach analogous to the rumen, but in contrast to ruminants, they produce little or no methane. The objective of this study was to identify the dominant organisms and pathways involved in hydrogenotrophy in the kangaroo forestomach, with the broader aim of understanding how these processes are able to predominate over methanogenesis. Stable isotope analysis of fermentation end products and RNA stable isotope probing (RNA-SIP) were used to investigate the organisms and biochemical pathways involved in the metabolism of hydrogen and carbon dioxide in the kangaroo forestomach. Our results clearly demonstrate that the activity of bacterial reductive acetogens is a key factor in the reduced methane output of kangaroos. In in vitro fermentations, the microbial community of the kangaroo foregut produced very little methane, but produced a significantly greater proportion of acetate derived from carbon dioxide than the microbial community of the bovine rumen. A bacterial operational taxonomic unit closely related to the known reductive acetogen Blautia coccoides was found to be associated with carbon dioxide and hydrogen metabolism in the kangaroo foregut. Other bacterial taxa including members of the genera Prevotella, Oscillibacter and Streptococcus that have not previously been reported as containing hydrogenotrophic organisms were also significantly associated with metabolism of hydrogen and carbon dioxide in the kangaroo forestomach.
authors.affiliation: Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Godwin
authors.affiliation: Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Alicia
authors.initials: A
authors.lastname: Kang
authors.affiliation: Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Lisa-Maree
authors.initials: LM
authors.lastname: Gulino
authors.affiliation: Centre for Marine BioInnovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Mike
authors.initials: M
authors.lastname: Manefield
authors.affiliation: Centre for Marine BioInnovation, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Maria-Luisa
authors.initials: ML
authors.lastname: Gutierrez-Zamora
authors.affiliation: Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Marco
authors.initials: M
authors.lastname: Kienzle
authors.affiliation: Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Diane
authors.initials: D
authors.lastname: Ouwerkerk
authors.affiliation: Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia.
authors.forename: Kerri
authors.initials: K
authors.lastname: Dawson
authors.affiliation: 1] Queensland Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia [2] School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland, Australia [3] Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Athol V
authors.initials: AV
authors.lastname: Klieve
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D002417:Cattle; D005285:Fermentation; D005753:Gastric Mucosa / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D007614:Macropodidae / Q000378:metabolism / Q000382:microbiology*; D008297:Male; D008697:Methane / Q000378:metabolism; D012417:Rumen / Q000382:microbiology; D013270:Stomach / Q000382:microbiology*
chemical_list: D001639:Bicarbonates; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D006859:Hydrogen; D008697:Methane