L-半胱氨酸转化菌株的选育及产酶条件优化

Breeding of High Enzyme Activity Strain for L - cysteine Bioconversion and Optimization of Its Enzyme - production Conditions

目的:选育高酶活L-半胱氨酸转化菌株并对产酶培养基进行统计优化。方法:利用紫外照射方法对假单胞菌Pseudo-monas sp.B-3进行诱变处理并采用响应面法优化诱变株产酶培养条件。结果:经诱变后选育出1株遗传性能稳定的高酶活L-半胱氨酸转化菌株Pseudomonas sp.C-46,其酶活力为1 459U/mL,较出发菌株提高了39.9%;经优化后该诱变菌株最佳产酶培养基组成为(g/L):DL-ATC.3H2O 8.6,甘油15.4,牛肉膏9.9,蛋白胨8,氯化钠8,MnSO4.H2O 0.4,酵母膏4。在此培养条件下酶活为1 671U/mL,菌体转化生成L-半胱氨酸的最高质量浓度可达5.1g/L,与出发菌株相比提高了21.4%。结论:获得了1株高酶活产L-半胱氨酸诱变菌株,并确定了其最佳产酶条件。

Objective： To obtain high L- cysteine enzyme activity strain and statistically optimize the enzyme -production conditions. Method ：Pseudomonas sp. B - 3 was mutated by UV - ray. Response surface methodology （RSM） was used to optimize its en- zyme- production medium. Result： After mutation, a mutant strain with high enzyme activity and good genetic stability designated as Pseudomonas sp. C -46 was obtained, of which L- cysteine enzyme activity improved to 1 459U/mL, namely increased by 39.9% com- pared with that of original strain. On basis of the mutant strain,the optimum enzyme -production medium was composed of （in g/L） ：DL - ATC . 3H2O 8. 6, Glycerol 15.4, Beef extract 9. 9, Peptone 8, NaCl 8, MnSO4 . H2O 0. 4, yeast extract 4. Under such conditions, The enzyme activity was reached 1 671U/mL and the yield of L - cysteine was 5. 1g/L,with an increase of 21.4% compared to that of initial strain. Conclusion：A high L- cysteine enzyme activity strain was obtained, and identified its optimum enzyme -production medium.