title: Ruminal fermentation of propylene glycol and glycerol.
abstract: Bovine rumen fluid was fermented anaerobically with 25 mM R-propylene glycol, S-propylene glycol, or glycerol added. After 24 h, all of the propylene glycol enantiomers and approximately 80% of the glycerol were metabolized. Acetate, propionate, butyrate, valerate, and caproate concentrations, in decreasing order, all increased with incubation time. Addition of any of the three substrates somewhat decreased acetate formation, while addition of either propylene glycol increased propionate formation but decreased that of butyrate. R- and S-propylene glycol did not differ significantly in either their rates of disappearance or the products formed when they were added to the fermentation medium. Fermentations of rumen fluid containing propylene glycol emitted the sulfur-containing gases 1-propanethiol, 1-(methylthio)propane, methylthiirane, 2,4-dimethylthiophene, 1-(methylthio)-1-propanethiol, dipropyl disulfide, 1-(propylthio)-1-propanethiol, dipropyl trisulfide, 3,5-diethyl-1,2,4-trithiolane, 2-ethyl-1,3-dithiane, and 2,4,6-triethyl-1,3,5-trithiane. Metabolic pathways that yield each of these gases are proposed. The sulfur-containing gases produced during propylene glycol fermentation in the rumen may contribute to the toxic effects seen in cattle when high doses are administered for therapeutic purposes.
authors.affiliation: National Soil Tilth Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50011, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Trabue
authors.forename: Kenwood
authors.initials: K
authors.lastname: Scoggin
authors.forename: Siska
authors.initials: S
authors.lastname: Tjandrakusuma
authors.forename: Mark A
authors.initials: MA
authors.lastname: Rasmussen
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Reilly
mesh_terms: D000818:Animals; D002417:Cattle; D002849:Chromatography, Gas; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D006801:Humans; D019946:Propylene Glycol / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism*; D012903:Smell; D013455:Sulfur / Q000032:analysis
chemical_list: D005232:Fatty Acids, Volatile; D019946:Propylene Glycol; D013455:Sulfur; D005990:Glycerol