Urea supplementation-induced changes of nickel-dependent microbial community lead to the reconstruction of rumen microbiome. gut metagenome isolate:goat

Urease is a kind of Ni-dependent enzyme that requires cofactor Ni for its activity. This study investigated the role of Ni in the reshaping of rumen microbiome after urea supplementation. It was found that rumen ammonia concentration and urease activity were significantly increased, while SCFAs concentrations had no significant changes after urea supplementation. Standard on the genome completeness more than 60%, 57 bacteria consisting of five kinds of Ni-dependent enzymes were detected in the metagenomic sequences. For these bacteria, the relative abundances of bacteria with urease and acetyl-CoA synthase were significantly increased, while the relative abundances of bacteria with glyoxalase I, [NiFe]-hydrogenase and lactate racemase, as well as that of the whole community, were significantly decreased after urea supplementation. Meantime, the functional modules related to the AA, glucose and lipid metabolism, as well as sulphur and nitrogen fixation, were significantly changed after urea supplementation. For the rumen microbiome, its structure and the functional modules related to the lipid and glucose metabolism were significantly changed after urea supplementation. These finding suggested that the reconstruction of rumen microbiome was induced by the compositional and functional changes of Ni-dependent microbial community after urea supplementation.