Enhanced α-ketoglutarate production in Yarrowia lipolytica WSH-Z06 by alteration of the acetyl-CoA metabolism

alpha-Ketoglutarate (alpha-KG) is an important intermediate in the tricarboxylic acid (TCA) cycle and has an important role in the regulation of the balance between carbon and nitrogen metabolism in most microorganisms. In previous research, a thiamine-auxotrophic yeast for alpha-KG overproduction was screened and named as Yarrowia lipolytica WSH-Z06. To enhance alpha-KG production and reduce by-product (mainly pyruvate) accumulation, the cofactor metabolism was regulated to redistribute the carbon flux from pyruvate to alpha-KG. The acetyl-CoA synthetase gene, ACS1, from Saccharomyces cerevisiae and the ATPcitrate lyase gene, ACL, from Mus musculus were expressed to regulate the acetyl-CoA metabolism in Y. lipolytica WSH-Z06. The resultant strains were designated as Y. lipolytica-ACS1 and Y. lipolytica-ACL, respectively. Both of the ACS1 and ACL genes could increase the level of acetyl-CoA and enhance the alpha-KG production. In a 3-L jar fermenter, the highest yield of alpha-KG in Y. lipolytica-ACL reached up to 56.5 g L-1 with an obvious decrease of pyruvate accumulation from 35.1 g L-1 to 20.2 g L-1. This study demonstrated that enhancing the acetyl-CoA availability could effectively increase the alpha-KG production in Y. lipolytica. (C) 2012 Elsevier B. V. All rights reserved.