Rumen methanogenic archaea use by-products of fermentation to carry out methanogenesis for energy generation. A key fermentation by-product is hydrogen (H2), which acts as the source of reducing potential for methane (CH4) formation in hydrogenotrophic methanogens. The in vitro cultivation of hydrogenotrophic rumen methanogens requires pressurised H2 which limits the ability to conduct high-throughput screening experiments with these organisms. The genome of the hydrogenotrophic methanogen Methanobrevibacter boviskoreani JH1T harbors genes encoding an NADP-dependent alcohol dehydrogenase and a F420-dependent NADP reductase, which may facilitate the transfer of reducing potential from ethanol to F420 via NADP. The aim of this study was to explore the anaerobic culturing of JH1T without pressurised H2, using a variety of short chain alcohols. The results demonstrate that in the absence of H2, JHIT can use ethanol, 1-propanol, and 1-butanol but not methanol, as a source of reducing potential for methanogenesis. The ability to use ethanol to drive CH4 formation in JH1T makes it possible to develop a high throughput culture-based bioassay enabling screening of potential anti-methanogen compounds. The development of this resource will help researchers globally to accelerate the search for methane mitigation technologies for ruminant animals. Global emissions pathways that are consistent with the temperature goal of the Paris Agreement, rely on substantial reductions of agricultural greenhouse gasses, particularly from ruminant animals.
Keywords: Alcohol dehydrogenase; Enteric methane; Methanobrevibacter; Methanogen; Rumen.
© 2023 The Authors. Published by Elsevier B.V.