In vivo C-13 NMR study of glucose and cellobiose metabolism by four cellulolytic strains of the genus Fibrobacter

The metabolism of glucose and cellobiose, products of cellulose hydrolysis, was investigated in four cellulolytic strains of the genus Fibrobacter: Fi brobacter succinogenes S85, 095, HM2 and Fibrobacter intestinalis NR9. In v ivo C-13 nuclear magnetic resonance was used to quantify the relative contr ibution of,glucose and cellobiose to metabolite production, glycogen storag e and cellodextrins synthesis in these four strains. The same features were found in all four strains of the genus Fibrobacter metabolizing simultaneo usly glucose and cellobiose: i) differential metabolism of glucose and cell obiose; glucose seems preferentially used for glycogen storage and energy p roduction, while part of cellobiose seems to be diverted from glycolysis, i i) synthesis of cellodextrins, mainly from cellobiose not entering into gly colysis, iii) accumulation of glucose 6-phosphate, iv) simultaneous presenc e of cellobiose phosphorylase and cellobiase activities. Although genetically diverse, the Fibrobacter genus appears to possess a ma rked homogeneity in its carbon metabolism.