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Studies on Factors Needed by Rumen Micro-Organisms for Cellulose Digestion In Vitro^{1, 2}

Ohio Agricultural Experiment Station

Abstract

In vitro studies, in which rumen microorganisms separated from the juice by centrifugation were used as the inoculum, were carried out for the purpose of investigating the nutritional requirements of these organisms. The rate of cellulose digestion was used as a measure of activity.

The addition of autoclaved rumen juice, extracts of various plant materials, molasses, or yeast extract markedly increased the rate of cellulose digestion.

Biotin, vitamin B₁₂, para-aminobenzoic acid, xanthine, uracil, guanine, adenine, when added to the basal medium improved cellulose digestion. However, the amount of cellulose digested was always less than that digested in flasks which contained rumen juice supernatant, a water extract of alfalfa, yeast, or molasses. This observation was taken to indicate that undetermined factors were present in these natural products which when added to the in vitro fermenation enhanced the microbial activity.

An active substance(s) was concentrated from rumen juice by lead acetate precipitation followed by alcohol extraction of the dried filtrate residue. This material could be adsorbed on Norite A and eluted but the eluate was less active than the original rumen juice. The addition of B-vitamins, purines, and uracil to the flasks along with the eluate fraction increased the rate of cellulose digestion above the level obtained with the eluate alone. This would indicate that the factor was not one of these known compounds found to be active for rumen microorganism in vitro.

¹ Published with the approval of the Director of the Ohio Agricultural Experiment Station, Wooster.

² The studies reported herein were supported in part by Grants-in-Aid from Swift and Company, Chicago, Illinois, and the Polychemicals Department, E. I. du Pont de Nemours and Company, Wilmington, Delaware.