posted on 2021-02-12, 14:36authored byWenqi Shi, Jie Li, Yanfang Chen, Xiaohang Liu, Yefu Chen, Xuewu Guo, Dongguang Xiao
Ethyl
acetate can be synthesized from acetyl-CoA and ethanol via a reaction by alcohol acetyltransferases (AATase) in
yeast. In order to increase the yield of acetyl-CoA, different terminators
were used to optimize the expressions of acetyl-CoA synthetase (ACS1/2)
and aldehyde dehydrogenase (ALD6) to increase the contents of acetyl-CoA
in Saccharomyces cerevisiae. ATF1 coding AATase was coexpressed in expression cassettes of ACS1/ACS2
and ALD6 to promote the carbon flux toward ethyl acetate from acetyl-CoA.
Further to improve ethyl acetate production, four heterologous AATase
including HuvEAT1 (Hanseniaspora uvarum), KamEAT1
(Kluyveromyces marxianus), VAAT (wild strawberry),
and AeAT9 (kiwifruit) were introduced. Subsequently mitochondrial
transport and utilization of pyruvate and acetyl-CoA were impeded
to increase the ethyl acetate accumulation in cytoplasm. Under the
optimal fermentation conditions, the engineered strain of PGAeΔPOR2
produced 1.69 g/L ethyl acetate, which was the highest value reported
to date by metabolic engineering methods.