[Addition of TCA cycle intermediates enhances pyruvate production]

The capability of utilizing the intermediates of TCA-cycle as the sole carbon source by the multi-vitamin auxotrophic yeast Torulopsis glabrata CCTCC M202019 under the conditions of vitamins limitation was demonstrated. Furthermore, the colony numbers grown on medium supplemented with glucose, acetate and one of the intermediates of TCA-cycle was higher than that of medium used glucose and acetate or medium used one of the intermediates of TCA-cycle carbon source. Among the intermediates of TCA-cycle used in this study, oxaloacetate was the best carbon source for the yeast and it was found that its presence stimulated the conversion of acetate to acetyl-CoA. In batch fermentation with glucose medium, the addition of 10 g/L of oxaloacetate improved the dry cell weight from 11.8 g/L to 13.6 g/L, and the productivity of pyruvate from 0.96 g x L(-1) x h(-1) to 1.19 g x L(-1) x h(-1), a 24% increase after 56 h growth. The yield of pyruvate on glucose was also improved as well, from 0.63 g/g to 0.66 g/g.