Influence of oxygen transfer rate and media composition on fermentation ofd-xylose byPichia stipitis NRRL Y-7124

Abstract

The optimization of ethanol production byPichia stipitis NRRL Y-7124 was analysed by ATP balance. Ethanol volumetric productivity was maximal (0.5–0.6 g/l h) only over a narrow range of oxygen transfer rates (3–5 mmol O2/l h). Trace element supplements increased ethanol volumetric productivity 20%. Biotin and thiamine did not significantly affect ethanol yield. Vitamins and trace elements were not synergistic. Organic nitrogen source from yeast extract was used for growth simultaneously to ammonia.