Preliminary Observations upon Factors Influencing Cellulose Digestion by Rumen Microorganisms

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Abstract
A laboratory method is described for studying cellulose digestion by rumen microorganisms. The major features of this method include the use of continuous 36-hour fermentation periods, in which the original starting inoculum was a mixed culture of organisms taken directly from the rumen of cattle. The inoculum used in the second and succeeding 36-hour periods consisted of half the residue from the preceding fermentation. Cellulose digestion was determined chemically on the half portions not used as inoculum, and Gram stains of the microflora were observed at the beginning and end of each fermentation period. Application of the method in preliminary trials resulted in data showing pronounced differences in the ability of rumen microorganisms to digest cellulose, depending upon additions or withdrawals from the nutrient medium as the fermentation periods progressed. Additions which proved helpful to cellulose digestion included a complex salt solution, the ash of alfalfa extract, autoclaved rumen liquid, and an autoclaved water extract of manure. Recovery trials with certain additions of these materials restored the ability to digest cellulose which had previously been lost through the omission of such additions.