黑曲霉原生质体诱变选育果胶酶高产菌株

Breeding of High Pectinase Producing Aspergillus niger Strain by Protoplast Mutagenesis

通过UV和NTG诱变筛选获得了2株高产果胶酶突变株。以果胶酶产生菌黑曲霉EIM6为诱变材料,采用1.5%的溶壁酶和1.5%的纤维素酶处理其对数生长期菌丝体2 h获得高质量的原生质体。采用UV25S或50μg/mL NTG诱变30 min,构建原生质体突变库,经刚果红果胶平板筛选获得果胶酶突变株,通过液体深层培养复筛获得高产突变株EIM6-U11、EIM6-N5,酶活力分别从46 598.08、46 598.08 U/mL提高至68 596.57、68 879.56 U/mL,分别提高了47.21%、47.82%。连续8次传代经发酵测酶活力表明高产突变株EIM6-U11、EIM6-N5具有较高的遗传稳定性。

Two peetinase high producing Aspergillus niger strains were obtained through screening after UV and NTG mutation. Pectinase producer Aspergillus niger EIM6 was used as mutation material to prepare protoplast adopting 1.5% helicase and 1.5% cellulase to treat its mycelia in the logarithmic phase for 2 h to obtain protoplast of high quality. A protoplast mutants library was established adopting UV exposure for 25 s and NTG mutagenesis for 30 min at 50 μg/mL, and obtained pectinase mutants through screening on Congo red pectin plate, and obtained pectinase high-yielding mutants EIM6-U11 and EIM6-N5 through re-screening with liquid submerged cultivation. Their enzyme activity increased respectively from 46 598.08 U/mL and 46 598.08 U/mL to 68 596.57 U/mL and 68 879.56 U/ mL, increased by 47.21% and 47.28% respectively. After successively passing 8 rounds of generation and proved with fermentation tests for their enzymatic activity, the high-yielding mutants of EIM6-U11 and EIM6-N5 proclaimed had fairly high genetic stability.