Enhancing a-ketoglutaric acid production in Torulopsis glabrata: increase of acetyl-CoA availability

Abstract:

[Objective] This study aimed at increasing the a-ketoglutaric acid production of a multi-vitamin auxotrophic yeast Torulopsis glabrata, by increasing the availability of acetyl-CoA. [Methods] For this, we expressed ACS2 encoding acetyl-CoA synthase from Saccharomyces cerevisiae in the pyruvate producer Torulopsis glabrata WSH-IP303. [Results] Compared with that of the parent strain, the acetyl-CoA synthase activity of the mutant ACS2-1 increased about 920% and the mutant could use acetate as the sole carbon source for growth (2.6 g/L dry cell weight). When growing with glucose, the acetyl-CoA concentration, a-ketoglutaric acid, and the value of C a-KG/Cpyr were 222%, 105% and 152% higher than those of the parent strain WSH-IP303, respectively. The addition of 4 g/L acetate to the culture broth of mutant ACS-1 led to a significant increase of these values to 355%, 147% and 275%, respectively, compared with that of the parent strain WSH-IP303. [Conclusion] The a-ketoglutaric acid concentration reached 17.8 g/L by increasing the availability of ace-tyl-CoA and this strategy may provide an alternative approach to enhance metabolite production in yeast.