果胶酶高产菌种的紫外诱变选育及其培养条件的响应面法优化

以果胶酶产生菌黑曲霉EIM6为出发菌株,初始果胶酶活为14 539 U/mL,经紫外诱变反复处理,摇瓶复筛和遗传稳定性试验,最终获得一株果胶酶高产菌株EIMU2。EIMU2菌株的形态特征发生了明显的改变,相较于原出发菌株EIM6,孢子色泽更黑,孢子团也较出发菌株大,菌丝与孢子上凝结有更多的液珠。复筛后EIMU2酶活为32 161 U/mL,较原出发菌株提高了1.212倍。进一步通过响应面法对EIMU2菌株的液体发酵培养条件进行优化。优化后的培养条件为甜菜渣1.83%,花生饼粉1.69%,(NH_4)_2SO_4 0.5%,K_2HPO_4 0.3%,CaCO_3 0.2%,MgSO_4 0.15%(w/v),接种量6%(v/v),装液量21.36 mL。优化的突变菌株产酶活性进一步提高至98 794.3 U/mL,提高了2.07倍。

Selection and optimization of a high pectinase-producing strain by UV mutation and response surface methodology

A pectinase-producing Aspergillus niger strain EIM6 was mutagenized by using UV radiation and after screening the mutant EIMU2 was obtained. The pectinase activity of EIMU2 was increased to 32 161 U/mL, 1. 212 times higher than that of the original A. niger EIM6. At the same time, morphological characteristics of EIMU2 changed obviously. The color of spore became deeper and the spore balls grew bigger. Through response surface methodology experiment, the optimal submerged fermentation conditions were obtained to further improve the production of pectinase from A. niger mutant EIMU2. The optimum medium contained （w/v） 1.83 % beet residue, 1.69% peanut cake powder, 0.5% （NH4）2SO4, 0.3% K2HPO4, 0.2% CaCO3, 0.15% MgSO4, 6% inoculum and 21.36 mL liquid volume. The optimum pectinase activity was increased by 208 % compared to that of the previous.