Construction of recombinant industrial S. cerevisiae strain with barley lipid-transfer protein 1 secretion capability and lower PrA activity
2011
Zhang, Hong-bo | Ruan, Hui | Li, Wei-fen | Zhang, Wei | Su, Zhong-rui | He, Guo-qing | Chen, Qi-he
Beer barley LTP1 in beer is an important component of beer foam, and it participates in the formation of beer foam. The digestion of beer barley LTP1 by proteinase A from brewing yeast leads to the decline of beer foam stability, especially for the unpasteurized beer. The objective of this study was to construct an industrial brewing yeast strain to secrete recombinant barley LTP1 into fermenting wort during beer fermentation for the foam stability improvement. We constructed barley LTP1 expression cassette and transformed into the host industrial yeast cells to replace partial PEP4 alleles using homologous recombination method. The expression of b-LTP1 was under control of the constitutive yeast ADH1 promoter, and the concentration of recombinant barley LTP1 secreted by recombinants reached 26.23 mg/L after incubation in YEPD medium for 120 h. The PrA activity of the recombinant strain declined compared with the host strain. The head retention of beer brewed with the recombinant industrial strain (326 ±Â 12 s) was improved when the host strain WZ65 (238 ±Â 7 s) and the constructed strain S.c-P-1 (273 ±Â 10 s) with partial PEP4 gene deficiency were used as control. The present study may provide reference for brewing industries and researches on beer foam stability.
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