Producing malonate in Saccharomyces cerevisiae via the β-alanine pathway

Abstract

Malonate is a high-value chemical that can be used to produce value-added compounds. Due to the toxic by-products and low product yield for malonate production through hydrolysis of cyanoacetic acid, microbial production methods have attracted significant attention. Previously, the β-alanine pathway has been engineered in Escherichia coli for malonate production. In this study, the β-alanine pathway was constructed in Saccharomyces cerevisiae by introducing the heterologous genes of BcBAPAT and TcPAND to convert l-aspartate to malonic semialdehyde, combining with co-expression genes of AAT2 and UGA2 to improve precursor supply and malonate producing. Through delta sequence-based integration of the two heterologous genes, the engineered strain produced with 7.21 mg/L malonate was screened. Further, replaced the succinic semialdehyde dehydrogenase gene UGA2 with yneI from E. coli which was utilized to produce malonate in previous study, increased the malonate titer to 7.96 mg/L in flask culture. Following optimization, fermentation of the final engineered strain in shake flasks yielded a maximum malonate titer of 12.83 mg/L, and this was increased to 91.53 mg/L during fed-batch fermentation in a 5 L bioreactor which increased by two-fold compared with that of the engineered strain overexpressing UGA2.