title: Effects of monensin and pH on the production and utilization of pyro-glutamate, a novel product of ruminal glutamine deamination.
abstract: Pure cultures of monensin-sensitive ruminal bacteria were involved in both the production and utilization of pyro-glutamate (pyrrolidone carboxylic acid), a novel product of glutamine fermentation, but the effect of monensin on pyro-glutamate accumulation in mixed cultures had not been assessed. Mixed ruminal bacteria (n = 3) fermented glutamine (40 mM) at a rapid rate (63 nmol/[mg protein-min]) and there was a transient increase in pyro-glutamate (3 mM). Monensin (5 ppm) decreased the rate of glutamine fermentation 70% and greatly enhanced the conversion of glutamine to pyro-glutamate (50 vs 7%). Glutamate was fermented at nearly the same rate as glutamine, and monensin eliminated glutamate fermentation. Glutamate was never converted to pyro-glutamate. Trypticase, a pancreatic digest of casein, contained pyro-glutamate, and a significant fraction (30%) of its N was never converted to ammonia. Pyro-glutamate utilization was reduced by monensin and low pH (less than 6.0). Based on these in vitro observations, pyro-glutamate could be a significant end-product of glutamine degradation when animals are fed monensin.
authors.affiliation: U.S. Department of Agriculture, Ithaca, NY.
authors.forename: J B
authors.initials: JB
authors.lastname: Russell
authors.forename: G J
authors.initials: GJ
authors.lastname: Chen
mesh_terms: D000818:Animals; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D002417:Cattle / Q000378:metabolism*; D003641:Deamination; D005260:Female; D005285:Fermentation; D005973:Glutamine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008985:Monensin / Q000494:pharmacology*; D011760:Pyrrolidinones / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism / Q000382:microbiology*
chemical_list: D011760:Pyrrolidinones; D005973:Glutamine; D008985:Monensin; D011761:Pyrrolidonecarboxylic Acid