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Constructing an amylolytic brewing yeast Saccharomyces pastorianus suitable for accelerated brewing
Zengran Liu1, Guangyi Zhang, Shigui Liu
1Bioscience and Bioengineering College, Hebei Economics and Business University, 47 Xuefu Road, Shijiazhuang 050061, PR China.
Journal of Bioscience and Bioengineering
|October 20, 2005
Summary
A new brewing yeast, Saccharomyces pastorianus, was engineered to break down starch and reduce unwanted compounds like diacetyl. This modified yeast maintains its brewing capabilities while improving fermentation efficiency and flavor profiles.
Area of Science:
- Biotechnology
- Food Science
- Microbiology
Background:
- Traditional brewing relies on specific yeast strains for fermentation.
- Starch utilization and byproduct formation are key challenges in brewing.
- Saccharomyces pastorianus is a crucial yeast in lager production.
Purpose of the Study:
- To engineer a Saccharomyces pastorianus strain capable of starch utilization.
- To reduce alpha-acetolactate synthase activity and diacetyl concentration in fermented wort.
- To assess the brewing performance of the recombinant yeast strain.
Main Methods:
- Disruption of the alpha-acetolactate synthase gene in Saccharomyces pastorianus.
- Introduction of the alpha-amylase gene as a selective marker.
- Fermentation tests to evaluate starch utilization and byproduct reduction.
Main Results:
- The recombinant Saccharomyces pastorianus strain effectively utilized starch as the sole carbon source.
- Alpha-acetolactate synthase activity was reduced by 30% in the engineered strain.
- Diacetyl concentration and residual oligosaccharides decreased by 70% and 25%, respectively.
- The recombinant strain demonstrated retained brewing performance.
Conclusions:
- Engineered Saccharomyces pastorianus can utilize starch and reduce key fermentation byproducts.
- The modified yeast offers potential for improved brewing efficiency and product quality.
- This recombinant strain provides a viable alternative for starch-based brewing processes.
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