Nitro- and nitrooxy-organic inhibitors of methanogenesis: revealing knowledge gaps and alternate ways in bovine rumen microbiome metabolism.
Mukhopadhyay Biswarup B
In the rumen, methanogens consume H2, generating methane and thermodynamically facilitating the production of short-chain fatty acids (SCFAs), ruminants' main energy source. Yet in animal trials, inhibiting methanogenesis by 27%-90% with 3-nitrooxypropanol minimally perturbs ruminal SCFA levels, sparing disproportionately low amount of H2. An Applied and Environmental Microbiology article (A. Castaneda, N. Indugu, K. Challa, K. Narayan, et al., Appl Environ Microbiol e01033-25, 2025, https://journals.asm.org/doi/10.1128/aem.01033-25) reports similar outcomes in an in vitro rumen experiment where ethyl-nitroacetate and ethyl-2-nitropropionate inhibited methanogenesis 100%. Hence, the rumen has fallback ways, perhaps evolved through exposures to plant metabolites. The nitroorganics offer an opportunity to determine the consequences of 100% inhibition of ruminal methanogenesis in live animals.