Genome-resolved multi-omics reveals alternative nitrogen assimilation pathways in rumen microbiota (microbiomejournal.biomedcentral.com)

• Many rumen bacteria lack the classical GS-GOGAT ammonia assimilation pathway.
• Dietary crude protein (10 vs 13%) minimally affects rumen microbiome composition.
• Forage-to-concentrate ratio alters expression of methionine biosynthesis genes.
• Nine ureolytic bacterial species and a phage with N-assimilation AMGs identified.

"Researchers from Ohio State University and Michigan State University used comparative genomics and genome-resolved multi-omics to investigate nitrogen utilization in the rumen microbiome. They found that many rumen bacteria lack the classical GS-GOGAT ammonia assimilation pathway and instead use alternative enzymes like glutamate dehydrogenase. A lamb feeding trial showed that dietary crude protein (10% vs 13%) had minimal impact on microbiome composition, while forage-to-concentrate ratio significantly affected gene expression, particularly the methionine biosynthesis pathway. The study also identified ureolytic bacteria and a phage carrying auxiliary metabolic genes for ammonia assimilation."