Unlocking lager's flavour palette by metabolic engineering of Saccharomyces pastorianus for enhanced ethyl ester production

Nicole X. Bennis, Jimme Bieseman, Jean Marc G. Daran*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

32 Downloads (Pure)

Abstract

Despite being present in trace amounts, ethyl esters play a crucial role as flavour compounds in lager beer. In yeast, ethyl hexanoate, ethyl octanoate and ethyl decanoate, responsible for fruity and floral taste tones, are synthesized from the toxic medium chain acyl-CoA intermediates released by the fatty acid synthase complex during the fatty acid biosynthesis, as a protective mechanism. The aim of this study was to enhance the production of ethyl esters in the hybrid lager brewing yeast Saccharomyces pastorianus by improving the medium chain acyl-CoA precursor supply. Through CRISPR-Cas9-based genetic engineering, specific FAS1 and FAS2 genes harbouring mutations in domains of the fatty acid synthesis complex were overexpressed in a single and combinatorial approach. These mutations in the ScFAS genes led to specific overproduction of the respective ethyl esters: overexpression of ScFAS1I306A and ScFAS2G1250S significantly improved ethyl hexanoate production and ScFAS1R1834K boosted the ethyl octanoate production. Combinations of ScFAS1 mutant genes with ScFAS2G1250S greatly enhanced predictably the final ethyl ester concentrations in cultures grown on full malt wort, but also resulted in increased levels of free medium chain fatty acids causing alterations in flavour profiles. Finally, the elevated medium chain fatty acid pool was directed towards the ethyl esters by overexpressing the esterase ScEEB1. The genetically modified S. pastorianus strains were utilized in lager beer production, and the resulting beverage exhibited significantly altered flavour profiles, thereby greatly expanding the possibilities of the flavour palette of lager beers.

Original languageEnglish
Pages (from-to)180-193
Number of pages14
JournalMetabolic Engineering
Volume85
DOIs
Publication statusPublished - 2024

Keywords

  • Brewing
  • CRISPR-Cas9
  • Ethyl esters
  • Ethyl hexanoate
  • Ethyl octanoate
  • Medium chain fatty acids
  • Saccharomyces pastorianus

Fingerprint

Dive into the research topics of 'Unlocking lager's flavour palette by metabolic engineering of Saccharomyces pastorianus for enhanced ethyl ester production'. Together they form a unique fingerprint.

Cite this