title: Changes in oxidation reduction potentials and volatile fatty acid production by rumen bacteria when methane synthesis is inhibited.
abstract: Rumen inoculum was cultured in specially designed fermenters that allowed simultaneous measurement of pH, oxidation-reduction potentials, and gas production. The cultures were maintained at pH 6.8 by addition of 1 M NaHCO3 and continuous infusion of artificial saliva. Gas flow was maintained at 20.0 ml/min with a stream of O2-free N2. Monensin at 7.0 micrograms/ml inhibited CH4 production 49% below control concentrations. The sodium salt of 2-bromoethanesulfonic acid added at an initial concentration of 5 x 10(-5) M inhibited CH4 production by 86% and increased H2 production from less than .5 mumol/min in the control to 24.5 mumol/min in the inhibited fermenter. The redox potentials in the control fermenter remained above -.20 V and did not change with the addition of monensin. Bromoethanesulfonic acid rapidly decreased the redox potential in the fermenter to -.33 V. Volatile fatty acid production was not significantly altered by the addition of 2-bromoethanesulfonic acid. The addition of monensin gave the expected decrease in acetate:propionate ratios, decreased acetate and butyrate production, and increased valerate (but not propionate) production.
authors.affiliation: Animal Research Centre, Agriculture Canada, Ottawa, Ontario.
authors.forename: F D
authors.initials: FD
authors.lastname: Sauer
authors.forename: R M
authors.initials: RM
authors.lastname: Teather
mesh_terms: D000476:Alkanesulfonates / Q000494:pharmacology*; D017738:Alkanesulfonic Acids; D000818:Animals; D002417:Cattle; D019605:Euryarchaeota / Q000187:drug effects / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000096:biosynthesis*; D005285:Fermentation / Q000187:drug effects*; D008697:Methane / Q000096:biosynthesis*; D008985:Monensin / Q000494:pharmacology*; D010084:Oxidation-Reduction; D012417:Rumen / Q000382:microbiology*
chemical_list: D000476:Alkanesulfonates; D017738:Alkanesulfonic Acids; D005232:Fatty Acids, Volatile; C018853:2-bromoethanesulfonic acid; D008985:Monensin; D008697:Methane