THE EFFECT OF THE PRESENCE OF GLUCOSE ON THE FERMENTATION OF MANNOSE BY THE ANAEROBIC FUNGUS NEOCALLIMASTIX FRONTALIS STRAIN RE1

The disappearance of mannose and the formation of formate, acetate, la ctate, ethanol and succinate by Neocallimastix frontalis strain RE1 oc curred slowly when mannose was the only substrate present. When an equ al quantity of glucose was present, the fermentation of mannose increa sed. Incubations with C-13-labelled mannose and glucose confirmed that the presence of both substrates resulted in increased product formati on from mannose and reduced product formation from glucose. The relati ve proportions of products formed from the two substrates varied, poss ibly in part due to differences in the rates of growth of the fungus. The strains of N. frontalis able to utilize mannose may have a competi tive advantage in the rumen ecosystem.