Surface-engineered Saccharomyces cerevisiae displaying α-acetolactate decarboxylase from Acetobacter aceti ssp xylinum
To convert α-acetolactate into acetoin by an α-acetolactate decarboxylase (ALDC) to prevent its conversion into diacetyl that gives beer an unfavourable buttery flavour.
We constructed a whole Saccharomyces cerevisiae cell catalyst with a truncated active ALDC from Acetobacter aceti ssp xylinum attached to the cell wall using the C-terminal anchoring domain of α-agglutinin. ALDC variants in which 43 and 69 N-terminal residues were absent performed equally well and had significantly decreased amounts of diacetyl during fermentation. With these cells, the highest concentrations of diacetyl observed during fermentation were 30 % less than those in wort fermented with control yeasts displaying only the anchoring domain and, unlike the control, virtually no diacetyl was present in wort after 7 days of fermentation.
Since modification of yeasts with ALDC variants did not affect their fermentation performance, the display of α-acetolactate decarboxylase activity is an effective approach to decrease the formation of diacetyl during beer fermentation.
KeywordsAcetobacter aceti Acetoin α-Acetolactate α-Acetolactate decarboxylase Beer Diacetyl Saccharomyces cerevsiae
- ASBC Methods of Analysis, online. Beer method 25. Diacetyl. Approved (2011) rev. (2014). American Society of Brewing Chemists, St. Paul doi:10.1094/ASBCMOA-Beer-25
- ASBC Methods of Analysis, online. Beer method 4. Alcohol. Approved (1958), rev. (2004). American Society of Brewing Chemists, St. Paul doi:10.1094/ASBCMOA-Beer-4
- ASBC Methods of Analysis, online. Beer method 5. Real Extract. Approved (1958), rev. (1982). American Society of Brewing Chemists, St. Paul doi:10.1094/ASBCMOA-Beer-5
- Inoue T (2008) Diacetyl in fermented foods and beverages. American Society of Brewing Chemists, St. Paul, p 139Google Scholar
- Inoue T, Yamamoto Y (1970) Diacetyl and beer fermentation. Proc Am Soc Brew Chem 28:198–208Google Scholar
- Krogerus K, Gibson BR (2013) 125th anniversary review: diacetyl and its control during brewery fermentation. J Inst Brew 119:86–97Google Scholar
- Ruehle G et al (2014) Headspace gas chromatography/electron capture detector analysis of total vicinal diketones in beer. J Am Soc Brew Chem 72:305–306Google Scholar