The effect of the presence of glucose on the fermentation of mannose by the anaerobic fungus Neocallimastix frontalis strain RE1

Abstract The disappearance of mannose and the formation of formate, acetate, lactate, ethanol and succinate by Neocallimastix frontalis strain RE1 occurred slowly when mannose was the only substrate present. When an equal quantity of glucose was present, the fermentation of mannose increased. Incubations with ¹³C-labelled mannose and glucose confirmed that the presence of both substrates resulted in increased product formation from mannose and reduced product formation from glucose. The relative proportions of products formed from the two substrates varied, possibly 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 competitive advantage in the rumen ecosystem.