Miron, J., Metabolic Unit, Institute of Animal Science, Aro, Volcani Center, Bet Dagan, Israel
Duncan, S.H., Rowett Research Institute, Bucksburn, Aberdeen, United Kingdom
Stewart, C.S., Rowett Research Institute, Bucksburn, Aberdeen, United Kingdom

Pure cultures and pair‐combinations of strains representative of the rumen cellulolytic species Ruminococcus flavefaciens, Fibrobacter succinogenes and Butyrivibrio fibrisovens were grown on cell‐wall materials from barley straw. Of the pure cultures, R. flavefaciens solubilized straw most rapidly. The presence of B. fibrisolvens, which was unable to degrade straw extensively in pure culture, increased the solubilization of dry matter by R. flavefaciens and the solubilization of cell‐wall carbohydrates by both R. flavefaciens and F. succinogenes. During fermentation, both R. flavefaciens and F. succinogenes released bound glucose and free and bound arabinose and xylose into solution. The accumulation of these sugars, especially arabinose and xylose, was greatly reduced in co‐cultures containing B. fibrisolvens, suggesting that significant interspecies cross feeding of the products of hemicellulose hydrolysis (particularly soluble bound xylose released by F. succinogenes) occurs during straw degradation by mixed cultures containing this species. Copyright © 1994, Wiley Blackwell. All rights reserved