Utilization of Glucose and Xylose in Ruminal Strains of Butyrivibrio fibrisolvens

The dual-substrate utilization pattern in cultures of five ruminal strains of Butyrivibrio fibrisolvens growing on glucose and xylose was investigated. Strains ATCC 19171 and 86 utilized glucose and xylose simultaneously. Other strains exhibited diauxic growth. Strains X1 and CE 51 exhibited classical diauxic growth in which glucose was utilized during the first phase. Strain X2D62 displayed atypical diauxic growth in which slow utilization of xylose was followed by rapid utilization of glucose after the xylose depletion. The ATP-dependent phosphorylation of glucose was found in all strains tested. The phosphoenolpyruvate-dependent phosphorylation of glucose was detected only in B. fibrisolvens CE 51.