Some properties of xylanase and xylobiase from mixed rumen organisms

Xylanase, free from xylobiase activity, has been obtained from crude extracts of mixed rumen organisms by fractionation on DEAE -cellulose. Xylobiase preparations were also obtained, but some xylanase activity was associated with all such fractions isolated.

Succinic Acid Production by Rumen Bacteria II. Radioisotope Studies on Succinate Production by Ruminococcus Flavefaciens

Strain C of R. flavejaciens ferments [1_14C]glucose with the production of methyl-labelled succinic and acetic acids, and the specific activity of the succinic acid produced is one-half that of the substrate. Fermentation of glucose in the presence of [14C]bicarbonate gives rise to carboxyl-labelled succinic acid. Formic acid is also labelled, either by direct exchange with 14C02 or by exchange of 14C02 with the carboxyl group of pyruvate. These results are compatible with the formation of succinate from glucose via the Embden-Meyerhof pathway and carboxylation of pyruvate or phosphoenolpyruvate.

Succinlc Acid Production Y Rumen Bacteria I. Isolation and Metabolism of Ruminococcus Flavefaciens

A strain of R. flavefaciens was isolated from the sheep rumen. Succinic acid was a major end� product of glucose fermentation by this organism when C02 was freely available, but in the absence of C02, the fermentation was nearly homolactic. The products of pyruvate fermentation were consistent with the proposition that pyruvate is an intermediate in the fermentation of glucose. Possible routes of the fermentation are discussed in the light of these findings.

The application of calorimetry to the study of ruminal fermentation in vitro

Techniques evolved for the study of heat production during the metabolism of pure cultures of microorganisms have been adapted for the study of certain aspects of the behaviour of the mixed cultures responsible for fermentation within the rumen. This approach allows whole untreated rumen contents, collected via fistulae, to be studied. The instrument is sensitive to very small changes in the overall evolution of heat, and so is capable of indicating overall changes in metabolic activity. In the samples studied in this series of experiments, the rates of heat and gas (carbon dioxide plus methane) production varied directly with the solids content of the sample. At 24 hr after feeding, the heat produced by ruminal fermentation in the sheep used was calculated to be between 480 and 1360 cal/hr. Ruminal fermentation was not affected by 240 mmoles of volatile fatty acid per litre, but was markedly inhibited by the same level of sodium ion. Lactate ion too appeared to have a specific inhibitory effect. The solid portion of rumen contents was found to possess much greater cellobiose-fermenting activity than did the fluid portion, and lactate accumulated as a transitory intermediate during cellobiose fermentation by whole contents. Small changes in pH had little effect on the course of fermentation in samples collected 16 hr after feeding. These findings and possibilities for the use of calorimetry in the study of complex biological systems are discussed.

Isolation and characterization of a hemicellulose-fermenting bacterium from the sheep rumen

A strictly anaerobic, Gram-negative, rod-like organism was isolated from sheep rumen liquor by culture in hemicellulose medium. The organism fermented several carbohydrates, including hemicellulose, producing acetic and lactic acids as the main end-products. Some biochemical characteristics of the organism are described and its taxonomic placement is discussed.

The hydrolysis of wheaten hay hemicellulose by a purified enzyme from rumen microorganisms

An enzyme hydrolyzing a largely insoluble preparation of hemicellulose from wheaten hay was purified from sheep rumen microflora. The enzyme catalysed the hydrolysis of hemicellulose to xylose, xylobiose, xylotriose, and higher oligosaccharides together with glucose and arabinose. Enzyme activity was rapidly destroyed by heating at temperatures above 40� and by raising the pH above the optimum of 6.0. Purified enzyme preparations did not hydrolyse starch or cellulose. A partial inhibition of hemicellulase activity was observed in the presence of p-chloromercuribenzoate.