The isolation and fermentation characteristics of Butyrivibrio species from ruminal ingesta

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Virginia Polytechnic Institute


Ten strains of anaerobic, gram negative, monotrichous, butyric acid-producing curved rods have been isolated from ingesta of the bovine rumen. These 10 strains of butyrivibrio represented 1/5 of all isolates at 1 x 10⁻⁸ dilutions. Morphological and physiological characteristics of the 10 strains and a strain isolated by gill and king (1958) have also been studied. No two of the isolates were identical in all reactions. Most of the organisms produced a large amount of butyric and some lactic, formic, propionic and succinic acids with the utilization of acetic acid in a rumen fluid glucose medium.

The fermentation carried on by these organisms was sensitive to most tested environmental changes. Studies with buffered rumen fluid-glucose media demonstrated a shift of the fermentation products with pH. Addition of fatty acids to this medium indicated that these organisms were active in the conversion of acetate and possibly propionate to butyrate. Two strains apparently had the ability to produce propionate at the expense of lactate. The results of the fermentation tests in 98 per cent rumen fluid medium showed that the tested strains used acetic (plus formic) or lactic (plus succinic) to produce butyric or propionic acid, and produced higher concentrations of fatty acids under a carbon dioxide atmosphere than under nitrogen. When rumen fluid and acetic acid were absent all strains had the ability to produce either formic or acetic acid.