Manipulating the pyruvate dehydrogenase bypass of a multi-vitamin auxotrophic yeast Torulopsis glabrata enhanced pyruvate production.

Abstract

To investigate the relationship between the activity of pyruvate dehydrogenase (PDH) bypass and the production of pyruvate of a multi-vitamin auxotrophic yeast Torulopsis glabrata. Torulopsis glabrata CCTCC M202019, a multi-vitamin auxotrophic yeast that requires acetate for complete growth on glucose minimum medium, was selected after nitrosoguanidine mutagenesis of the parent strain T. glabrata WSH-IP303 screened in previous study [Li et al. (2001) Appl. Microbiol. Biotechnol. 55, 680-685]. Strain CCTCC M202019 produced 21% higher pyruvate than the parent strain and was genetically stable in flask cultures. The activities of the pyruvate metabolism-related enzymes in parent and mutant strains were measured. Compared with the parent strain, the activity of pyruvate decarboxylase (PDC) of the mutant strain CCTCC M202019 decreased by roughly 40%, while the activity of acetyl-CoA synthetase (ACS) of the mutant increased by 103.5 or 57.4%, respectively, in the presence or absence of acetate. Pyruvate production by the mutant strain CCTCC M202019 reached 68.7 g l(-1) at 62 h (yield on glucose of 0.651 g g(-1)) in a 7-l jar fermentor. The increased pyruvate yield in T. glabrata CCTCC M202019 was due to a balanced manipulation of the PDH bypass, where the shortage of cytoplasmic acetyl-CoA caused by the decreased activity of PDC was properly compensated by the increased activity of ACS. Manipulating the PDH bypass may provide an alternative approach to enhance the production of glycolysis-related metabolites.