title: Effects of combinations of substrates on maximum growth rates of several rumen bacteria.
abstract: Five rumen bacteria, Selenomonas ruminantium, Bacteroides ruminicola, Megasphaera elsdenii, Butyrivibrio fibrisolvens, and Streptococcus bovis were grown in media containing nonlimiting concentrations of glucose, sucrose, maltose, cellobiose, xylose and/or lactate. Each bacterium was grown with every substrate that it could ferment in every possible two-way combination. Only once did a combination of substrates result in a higher maximum growth rate than that observed with either substrate alone. Such stimulations of growth rate would be expected if specific factors unique to individual substrates (transport proteins and/or enzymes) were limiting. Since such synergisms were rare, it was concluded that more general factors limit maximum growth rates in these five bacteria.
authors.affiliation: Department of Animal Science, University of California, Davis, California 95616.
authors.forename: J B
authors.initials: JB
authors.lastname: Russell
authors.forename: F J
authors.initials: FJ
authors.lastname: Delfino
authors.forename: R L
authors.initials: RL
authors.lastname: Baldwin