UTILIZATION OF GLUCOSE AND XYLOSE IN RUMINAL STRAINS OF BUTYRIVIBRIO-FIBRISOLVENS

The dual-substrate utilization pattern in cultures of five ruminal str ains of Butyrivibrio fibrisolvens growing on glucose and xylose was in vestigated. Strains ATCC 19171 and 86 utilized glucose and xylose simu ltaneously. Other strains exhibited diauxic growth. Strains X1 and CE 51 exhibited classical diauxic growth in which glucose was utilized du ring the first phase. Strain X2D62 displayed atypical diauxic growth i n which slow utilization of xylose was followed by rapid utilization o f glucose after the xylose depletion. The ATP-dependent phosphorylatio n of glucose was found in all strains tested. The phosphoenolpyruvate- dependent phosphorylation of glucose was detected only in B. fibrisolv ens CE 51.