Enzyme and Metabolic Engineering Strategies for Biosynthesis of a-Farnesene in Saccharomyces cerevisiae

a-Farnesene, a type of acyclic sesquiterpene, is an important raw material in agriculture, aircraft fuel, and the chemical industry. In this study, we constructed an efficient a-farnesene-producing yeast cell factory by combining enzyme and metabolic engineering strategies. First, we screened different plants for a-farnesene synthase (AFS) with the best activity and found that AFS from Camellia sinensis (CsAFS) exhibited the most efficient a-farnesene production in Saccharomyces cerevisiae 4741. Second, the metabolic flux of the mevalonate pathway was increased to improve the supply of the precursor farnesyl pyrophosphate. Third, inducing site-directed mutagenesis in CsAFS, the CsAFS(W281C) variant was obtained, which considerably increased a-farnesene production. Fourth, the N-terminal serine-lysine-isoleucine-lysine (SKIK) tag was introduced to construct the SKIK similar to CsAFS(W281C) variant, which further increased a-farnesene production to 2.8 g/L in shake-flask cultures. Finally, the a-farnesene titer of 28.3 g/L in S. cerevisiae was obtained by fed-batch fermentation in a 5 L bioreactor.