采用4株米曲霉菌种(j2、y2、x42、x72)与对照米曲霉菌株(沪酿3.042)制备大曲,探究其所产中性蛋白酶、酸性蛋白酶、α-淀粉酶以及糖化酶在盐浓度为0%、5%、10%、15%、20%下酶活力变化。实验结果表明,5株菌株所产酶系中,中性蛋白酶活随盐水浓度的增加显著(P<0.05)下降,酸性蛋白酶和糖化酶在5%盐浓度下活力显著下降(P<0.05),随后酶活力下降速率减慢,α-淀粉酶在5%的盐浓度下无显著下降(P>0.05),随后下降速率加快。此外,相同盐浓度下淀粉酶比蛋白酶更稳定,5株米曲霉菌株的α-淀粉酶和糖化酶在20%的盐浓度下残留率均达到50%。菌株y2、j2所产中性蛋白酶和菌株x72所产酸性蛋白酶的耐盐性优于对照菌株。

The activity of protease and amylase from four strains(j2,y2,42,x72) were compared with Aspergillus oryzae 3.042,and the changes with various salinity of 0%,5%,10%,15%,20% were measured.The activity of neutral protease decreased significantly(P<0.05) with the increase of salt concentration.The activity of acidic protease and glucoamylase were decreased drastically(P<0.05) under 5% salt concentration and followed by a gently decline.The activity of α-amylase at 5% salt concentration had no significant decrease(P>0.05) but followed by a steep drop.Besides,the amylase was much more stable than the protease in the same sodium chloride solution,and the residual activities of α-amylase and glucoamylase were up to 50% in five strains under 20% salt concentration.The decline rate of neutral protease from strain y2,j2 and acidic protease from strain x72 were all lower than those from control group.