Metabolic engineering for enhanced fatty acids synthesis in Saccharomyces cerevisiae

Microbial production of biofuel has attracted significant attention in recent years. The fatty acids are important precursors for the production of fuels and chemicals, and its biosynthesis is initiated by the conversion of acetyl-CoA to malonyl-CoA which requires acetyl-CoA as key substrate. Herein, the yeast Saccharomyces cerevisiae was proposed to be metabolically engineered for cytosol acetyl-CoA enhancement for fatty acid synthesis. By gene disruption strategy, idh1 and idh2 genes involved in citrate turnover in tricarboxylic acid cycle (TCA cycle) were disrupted and the citrate production level was increased to 4- and 5-times in mutant yeast strains. In order to convert accumulated citrate to cytosol acetyl-CoA, a heterologous ATP-citrate lyase (ACL) was overexpressed in yeast wild type and idh1,2 disrupted strains. The wild type strain expressing act mainly accumulated saturated fatty acids: C14:0, 06:0 and C18:0 at levels about 20%, 14% and 27%, respectively. Additionally, the idh1,2 disrupted strains expressing act mainly accumulated unsaturated fatty acids. Specifically in Delta idh1 strain expressing act, 80% increase in 06:1 and 60% increase in C18:1 was detected. In Delta idh2 strain expressing act, 60% increase in C16:1 and 45% increase in 08:1 was detected. In Delta idh1/2 strain expressing act, there was 92% increase in C16:1 and 77% increase in C18:1, respectively. The increased fatty acids from our study may well be potential substrates for the production of hydrocarbon molecules as potential biofuels. (C) 2013 Elsevier Inc. All rights reserved.