低蛋白酶A酵母菌株的选育及其基因层面初探

Optimization of lower-level protenase A and preliminary study on genetic perspective

以啤酒酵母M4Ⅰ为出发菌株,紫外诱变后通过96微孔板法初筛、Bradford法复筛,采用荧光底物法确定酵母蛋白酶A分泌量,最终得到4株低产蛋白酶A的突变株M4Ⅰ-4、M4Ⅰ-27、M4Ⅰ-39、M4Ⅰ-45。与出发菌株相比,4株突变株发酵后的蛋白酶A活力分别降低了83.6%、29.8%、80.5%、79.7%,双乙酰还原能力相近,各种风味物质含量除M4Ⅰ-27略有降低。经氨基酸序列比对分析发现,4株突变株共有7个氨基酸发生突变、1个同义突变。

Using brewing yeast MⅠ4 as the original strain,induced by ultraviolet,with 96 well plate as preliminary screening method and Bradford method as second screening method,fluorescent substracte was introduced to determine the final content of proteinase A.Four brewing yeasts with lower-level proteinase A were bred,they were MⅠ4-4,MⅠ4-27,MⅠ4-39 and MⅠ4-45.Compared with the original strain,the four mutation strains proteinase A activity decreased by 83.6%,29.8%,80.5%,79.7% and glucose degradate capacity reduced in a small range except MⅠ4-27.The diacetyl reducing capacity was similar,and the flavor substract content were slightly lower except MⅠ4-27.Compared with the original strain,the four mutants had seven amino acid mutation and a synonymous mutation in the amino acid sequence of proteinase A.