紫外诱变选育米曲霉高产蛋白酶菌株

Breeding Aspergillus oryzae Strain with High Protease Activity by Ultraviolet Induced Mutation

摘要:

以从自然发酵黄豆酱中筛选的5株野生米曲霉为供试菌株，以这些菌株产蛋白酶（酸、中、碱）、淀粉酶(α-淀粉酶、糖化酶)活力大小为评价标准，筛选出米曲霉K61作为诱变出发菌株。采用紫外诱变对米曲霉K61菌株进行改造，最终筛选出一株蛋白酶活力高且遗传性能稳定的突变株Y29。将米曲霉Y29菌株应用于黄豆酱的生产中，并与目前工业生产中广泛应用的米曲霉沪酿3.042菌株进行比较。性能实验结果表明米曲霉Y29菌株的蛋白酶（酸、中、碱）活力明显高于米曲霉沪酿3.042菌株，但α-淀粉酶、糖化酶、生长速度和孢子数这4个指标两者的差异并不显著；制酱品质试验结果表明，米曲霉Y29菌株的酱香更浓郁一些，氨基酸态氮含量达到0.77g/100mL，高于米曲霉沪酿3.042菌株，其它指标均符合国家标准GB2718-1996。

Abstract:

Based on the assessment of protease (acid，neutral and alkaline protease) activity and amylase activity (α- amylase and β- amylase)，one Aspergillus oryzae K61 was selected from five wild Aspergillus oryzae which are original from spontaneous fermented soybean paste.One Aspergillus oryzae Y29 was screened with ultraviolet radiation.The Aspergillus oryzae Y29 can produce higher protease activity than original Aspergillus oryzae K61，and its hereditary stability is higher.Compared with Aspergillus oryzae 3.042，the Aspergillus oryzae Y29 showed higher protease activity，however，the both strains did not have significant difference on the amylase activity，growing speed of the strain and number of spore.Both strains were applied to producing soybean paste.The soybean that was produced by Aspergillus oryzae Y29 has full-bodied soybean paste flavor，and the soluble nitrogen (0.77g/100ml) is higher than the Aspergillus oryzae 3.042.