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Modulating the distribution of fluxes among respiration and fermentation by overexpression of HAP4 in Saccharomyces cerevisiae

2001; Oxford University Press; Volume: 1; Issue: 2 Linguagem: Inglês

10.1111/j.1567-1364.2001.tb00025.x

1567-1364

Antonius J. A. van Maris, Barbara M. Bakker, Michael R. Brandt, André Boorsma, M. Joost Teixeira de Mattos, Leslie A. Grivell, Jack T. Pronk, J.G. Blom,

Biofuel production and bioconversion

The tendency of Saccharomyces cerevisiae to favor alcoholic fermentation over respiration is a complication in aerobic, biomass-directed applications of this yeast. Overproduction of Hap4p, a positive transcriptional regulator of genes involved in respiratory metabolism, has been reported to positively affect the balance between respiration and fermentation in aerobic glucose-grown batch cultures. In this study, the effects of HAP4 overexpression have been quantified in the prototrophic S. cerevisiae strain CEN. PK 113-7D under a variety of growth conditions. In aerobic glucose-limited chemostat cultures, overexpression of HAP4 increased the specific growth rate at which aerobic fermentation set in by about 10% relative to the isogenic wild-type. Upon relief of glucose-limited conditions, the HAP4-overexpressing strain produced slightly less ethanol than the wild-type strain. The effect of Hap4p overproduction was most drastic in aerobic, glucose-grown chemostat cultures in which ammonium was limiting. In such cultures, the biomass yield on glucose was double that of the wild-type.