ARS | Publication request: AMYLOLYTIC BACTERIA THAT PREVENT LACTATE ACCUMULATION DURING IN VITRO RUMINAL FERMENTATION

Submitted to: Conference on Rumen Function
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 2000
Publication Date: N/A

Technical Abstract: The goal of this study is to investigate the potential use of amylolytic bacteria in the prevention of rumen acidosis in high-producing dairy cattle. Ruminal amylolytic bacteria were isolated from a rapid turnover (30%/hr) starch fermentor. This fermentor had been inoculated with highly diluted rumen contents from a grain-fed cow. Strains of amylolytic bacteria were screened for their potential to direct starch fermentation away from lactic acid production. Strain 25A (10**7) CFU/ml) reduced the accumulation of lactate by 90% when added to mixed rumen fermentations that contained excess soluble carbohydrates. Lactic acid accumulated to high concentrations (70 mM) in control fermentations. When strain 25A was combined with Megasphaera elsdenii, strain Z2, lactate accumulation was reduced by 99%. An analysis of 16S rRNA sequences indicated that the amylolytic bacterium, strain 25A, a short Gram-negative rod, is not phylogenetically clustered to Prevotella, Bacteroides, Flavobacterium, or Cytophaga. Strain 25A used starch as well as cellobiose, pectin and xylan. Succinate and acetate were the major fermentation products when grown on starch. This bacterium possesses 12-methyltetradecanoic (anteiso-C15:0) acid as a major cell wall fatty acid. Other predominant acids included C16:0, and iso 15:0. Further characterization of this bacterium is necessary before it can be identified. We will continue our investigations to determine if practical methods can be developed to direct ruminal starch fermentation away from lactate production.