A comparative radiorespirometric study of glucose metabolism in yeasts

A comparative radiorespirometric study of glucose metabolism in glucose-limited chemostat cultures of Saccharomyces cerevisiae, Candida utilis and Rhodosporidium toruloides was performed in an attempt to estimate the contribution of the hexose monophosphate (HMP) pathway to glucose metabolism. Radioactively labelled glucose was administered directly to the cultures in a constant substrate feed, without disturbance of the steady state. The 14CO2 yields from [1-14C]- and [6-14C]-glucose demonstrated that the HMP pathway activities for the three yeasts were very similar. Furthermore, a quantitative analysis of results indicated that the HMP pathway activities were close to the theoretical minimum needed to cover the NADPH requirement for biomass formation.