Journal Article

The effect of 3-nitrooxypropanol, a potent methane inhibitor, on ruminal microbial gene expression profiles in dairy cows

Melgar, Audino, Hennessy, Meagan, Indugu, Nagaraju, Pitta, Dipti W., Hristov, Alexander, Narayan, Kapil, Duval, Stephane, Vecchiarelli, Bonnie, Kindermann, Maik, Walker, Nicola, Challa, Krishna

2022

Overview

Background Enteric methane emissions from dairy cows are an environmental problem as well as a gross feed energy loss to the animal. Methane is generated in the rumen by methanogenic archaea from hydrogen (H 2 ) + carbon dioxide and from H 2 + methanol or methylamines. The methanogenic substrates are provided by non-methanogens during feed fermentation. Methane mitigation approaches have yielded variable results, partially due to an incomplete understanding of the contribution of hydrogenotrophic and methylotrophic archaea to methanogenesis. Research indicates that 3-nitrooxypropanol (3-NOP) reduces enteric methane formation in dairy cows by inhibiting methyl-coenzyme M reductase (MCR), the enzyme responsible for methane formation. The purpose of this study was to utilize metagenomic and metatranscriptomic approaches to investigate the effect of 3-NOP on the rumen microbiome and to determine the fate of H 2 that accumulates less than expected under inhibited methanogenesis. Results The inhibitor 3-NOP was more inhibitory on Methanobrevibacter species than methanol-utilizing Methanosphaera and tended to reduce the gene expression of MCR. Under inhibited methanogenesis by 3-NOP, fluctuations in H 2 concentrations were accompanied by changes in the expression of [FeFe] hydrogenases in H 2 -producing bacteria to regulate the amount of H 2 production. No previously reported alternative H 2 sinks increased under inhibited methanogenesis except for a significant increase in gene expression of enzymes involved in the butyrate pathway. Conclusion By taking a metatranscriptomic approach, this study provides novel insights on the contribution of methylotrophic methanogens to total methanogenesis and regulation of H 2 metabolism under normal and inhibited methanogenesis by 3-NOP in the rumen. -iX6YPbp4qKjzQQ25nvbCQ Video Abstract

• Publisher: BioMed Central,Springer Nature B.V,BMC
• Subject: Animals / Bioinformatics / Biomedical and Life Sciences / Biomedicine / Carbon dioxide / Cattle / Coenzyme M / Contribution of Climate Change to the spread of Infectious Diseases / Dairy cattle / Emissions / Enteric methane / Enzymes / Euryarchaeota - metabolism / Feeds / Female / Fermentation / Gene expression / Hydrogenases / Medical Microbiology / Metagenomics / Methane / Methane - metabolism / Methane mitigation / Methanobacteriaceae - metabolism / Methanogenesis / Methanogenic archaea / Methanogenic bacteria / Methanol / Methanol - metabolism / Microbial Ecology / Microbial Genetics and Genomics / Microbiology / Microbiomes / Propanols / Rumen / Rumen - microbiology / Ruminal methanogenesis / Total and metabolically active microbes / Transcriptome / Virology