Effects of the loss of triose phosphate isomerase activity on carbon metabolism in Kluyveromyces lactis

The effect of the loss of triose phosphate isomerase activity on carbon metabolism in Kluyveromyces lactis was studied in batch and in continuous cultures. The KltpiI mutant was able to grow on media containing glucose as the sole carbon source both in batch and in continuous culture, unlike the corresponding S. cerevisiae mutant. In K. lactis tpiI mutant no glycerol production was detected in chemostat cultivations. DHAP accumulation triggers glycerol production only when glucose is the sole carbon source in excess. The analysis of the activities of some key enzymes of carbon metabolism shows that in chemostat cultivations on mixed-substrates the activities of enzymes involved in ethanol assimilation are higher both in K. lactis wild type and mutant strains than in S. cerevisiae.