Construction of self-cloning industrial brewing yeast with high-glutathione and low-diacetyl production
نویسندگان
چکیده
Self-cloning strains of industrial brewing yeast were constructed, in which one allele of a-acetohydroxyacid synthase (AHAS) gene (ILV2) was disrupted by integrating Saccharomyces cerevisiae genes, c-glutamylcysteine synthetase gene (GSH1) and copper resistant gene (CUP1) into the locus of ILV2. The self-cloning strains were selected for their resistance to CuSO4 and identified by PCR amplification. The results of AHAS and glutathione (GSH) assay from fermentation with the self-cloning strains in 500-mL conical flask showed that AHAS activity decreased and GSH content increased compared with that of host yeasts. The results of pilot scale brewing in 5-L fermentation tank also indicated that GSH content in beer fermented with self-cloning strains T5-3 and T31-2 was 1.3 fold and 1.5 fold of that of host QY5 and QY31, respectively; and diacetyl content decreased to 64% and 58% of their hosts, respectively. The self-cloning strains do not contain any heterologous DNA, they may be more acceptable to the public.
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