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A small scale rumen incubation system to screen chemical libraries for potential methane inhibitors

Muetzel, Stefan, Ronimus, Ron S., Lunn, Kristy, Kindermann, Maik, Duval, Stephane, Tavendale, Michael
Animal feed science and technology 2018 v.244 pp. 88-92
anthraquinones, fermentation, hydrogen production, methane, methane production, methanogens, rumen fermentation, rumen fluids, ruminants, screening
There is currently an urgent need for effective anti-methanogen small molecule inhibitors to help control ruminant methane emissions on a global scale. No assays system has yet been reported that would enable high-throughput screening of either rumen methanogen cultures or an assay system that utilises rumen fluid. We report here the development of a high-throughput 0.2 ml rumen fluid-based 96-well screening system that incorporates a simple substrate for fermentation with a short incubation time The fermentation parameters determined are total gas, methane and hydrogen production. The system markedly enhances the number of samples that can be processed (∼1000 incubation vials per week) compared to previously published assays. The system does not try to mimic rumen fermentation but is a means of screening compounds for their potential effect against rumen methanogens. We also assessed the system using known rumen anti-methanogen inhibitory compounds, a set of anthraquinone derivatives and 3-nitrooxypropanol. The system can differentiate between specific methane inhibition and the inhibition of overall fermentation and it discriminates between molecules that act as methanogen inhibitors and those acting as electron sinks.