转谷氨酰胺酶高产突变株的紫外线诱变选育及发酵条件研究

摘要

Streptoverticillium mobaraense is used for genetic breeding through ultraviolet mediated genetic mutation tests.Efficient MTG-producing mutant is determined according to the resultant mu-tant isolation analysis, and its fermentation condition is studied to obtain higher MTG activity. Through both primary and secondary screening tests,an effective mutant strain named Streptomyces sp.G-17 is finally obtained and its MTG productivity is 0.86 U/mL,which is 2.4-folds higher than that of initial strain.The effects of the culture conditions and the main compositions of fermentation medium on the MTG production are investigated,and the optimal fermentation conditions are as fol-lows:culture medium initial pH 7.0,100μg/L CaCl2 ,inoculum size of 10%,fermentation tempera-ture of 30 ℃, 200 r/min and shaking culture of 48 h. Under these conditions, the enzyme productivity is significantly enhanced and G-1 7 strain could stably repeat MTG-producing ability up to 1 .2 7 U/mL,which is 4 times higher than that of original strain.%以茂源链霉菌为出发菌株，对其进行紫外线诱变，通过初筛复筛，选育出性能稳定的高产突变菌株G-17，其酶活力达到0．86 U/mL，相对于出发菌株提高了2．4倍。对影响突变菌株G-17摇瓶液态发酵条件进行了研究，确定发酵的最佳条件为：培养基初始 pH 为7．0，100μg/L CaCl2，接种量10％（V/V），发酵温度30℃，转速200 r/min，摇床震荡培养48 h；最佳发酵条件下，发酵液中转谷氨酰胺酶活力达到1．27 U/mL。