Enhanced ethyl caproate production of Chinese liquor yeast by overexpressing EHT1 with deleted FAA1

J Ind Microbiol Biotechnol. 2014 Mar;41(3):563-72. doi: 10.1007/s10295-013-1390-3. Epub 2013 Dec 27.

Abstract

The fruity odor of Chinese liquor is largely derived from ester formation. Ethyl caproate, an ethyl ester eliciting apple-like flavor, is one of the most important esters in the strong aromatic Chinese liquor (or Luzhou-flavor liquor), which is the most popular and best-selling liquor in China. In the traditional fermentation process, ethyl caproate in strong aromatic liquor is mainly produced by aroma-producing yeast, bacteria, and mold with high esterification abilities in a mud pit at later fermentation stages at the expense of both fermentation time and grains rather than by the ethanol-fermenting yeast Saccharomyces cerevisiae. To increase the production of ethyl caproate by Chinese liquor yeast (S. cerevisiae AY15) and shorten the fermentation period, we constructed a recombinant strain EY15 by overexpressing EHT1 (encoding ethanol hexanoyl transferase), in which FAA1 (encoding acyl-CoA synthetases) was deleted. In liquid fermentation of corn hydrolysate and solid fermentation of sorghum, ethyl caproate production by EY15 was remarkably increased to 2.23 and 2.83 mg/L, respectively, which were 2.97- and 2.80-fold higher than those of the parental strain AY15. Furthermore, an increase in ethyl octanoate (52 and 43 %) and ethyl decanoate (61 and 40 %) production was observed. The differences in fermentation performance between EY15 and AY15 were negligible. This study resulted in the creation of a promising recombinant yeast strain and introduced a method that can be used for the clean production of strong aromatic Chinese liquor by ester-producing S. cerevisiae without the need for a mud pit.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / genetics
  • Alcoholic Beverages*
  • Caproates / metabolism*
  • China
  • Coenzyme A Ligases / genetics
  • Coenzyme A Ligases / metabolism
  • Fermentation
  • Industrial Microbiology*
  • Odorants
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics

Substances

  • Caproates
  • Saccharomyces cerevisiae Proteins
  • Acyltransferases
  • EHT1 protein, S cerevisiae
  • Coenzyme A Ligases
  • ethyl hexanoate