等离子体注入法诱变选育高产酸性蛋白酶菌株的研究

Study on mutation breeding of high acid protease-producing strains by plasma mutagenesis

采用等离子注入法诱变选育高产酸性蛋白酶的高产菌株。通过对初始菌株宇佐美曲霉M-537的等离子体诱变,酪蛋白平板初筛,液态发酵复筛等过程,筛选到1株稳定性好、酸性蛋白酶产量高的变变株,产酶能力从最初的4.15 U/mL提高到12.34 U/mL,提高率达197.3%。连续传代6次,产酶能力变化不大,说明该突变株遗传性稳定。为进一步增加目标产物的产量,试验采用单因素试验和响应面实验分析,优化了变异菌株的生长培养基条件,最终确定培养基豆饼粉浓度为51 g/L,玉米粉浓度为10.0 g/L,KH2PO4浓度为3.0 g/L。经优化条件后,突变菌产酸性蛋白酶酶活力达到33.1 U/mL。

Attempts were made for hyper production of acid protease by a strain of Aspergil-lus usamil 537 through irradiation mutagenesis. Plasma was applied for obtainning an acid prote-ase high-yield production strain. After screening using directed screening assay, only one high-yield mutant was selected, which produced 12.34 U/mL from initial 4. 15 U/mL of acid protease, which was 197.3 % higher than that produced by parent strain. Through six-generation investiga-tion, the capability of acid protease production of these two mutants was stable. Single-factor test and response surface analysis test were applied for optimizing medium, soybean cake 51 g/L, corn meal 10.0 g/L, KH2PO, 3.0 g/L were finally determined. After optimization condition, acid protease enzymatic activity of mutation bacterium reached 33.1 U/mL.