L-缬氨酸产生菌JVHK597的选育及无机盐对其产酸量的影响

目的]筛选L-缬氨酸高产菌株并研究其发酵条件。方法]以黄色短杆菌（Brebvibacterium flavum）突变株ZGH6128为出发菌株,采用紫外线（UV）、硫酸二乙酯（DES）和亚硝基胍（NTG）3种诱变剂进行诱变处理,通过摇瓶培养筛选出L-缬氨酸高产突变菌株。结果]经过UV、DES和NTG 3种诱变剂处理菌株ZGH6128,逐步获得菌株JVHK597,并具有Leu营养缺陷、Ile营养缺陷、Met营养缺陷、α-AB抗性、2-TA抗性5种遗传标记。在未优化的条件下,菌株JVHK597摇瓶发酵72 h的产酸量达41.2 g/L。8次传代试验结果表明,菌株JVHK597的产酸能力稳定,经鉴定,菌株JVHK597的基因型为（Leu-,Ile-,Met-,α-ABr,2-TAr）,遗传标记具有稳定性。发酵培养基中硫酸镁（MgSO4.7H2O）和磷酸二氢钾的含量分别为0.6和1.4 g/L时,最有利于菌株生产L-缬氨酸。结论]试验筛选出了L-缬氨酸高产菌株JVHK597,并为其发酵培养提供了指导。

Breeding of of L-valine Producing Strain JVHK597 and Influence of Inorganic Salt on Its Acid Production

Objective]The aim was to screen superior strain of L-valine and study its fermentation condition.Method]With the mutant strain ZGH6128 of Brebvibacterium flavum as initial strain,3 kinds of mutagens of ultraviolet(UV),diethyl sulfate(DES) and nitrosoguanidine(NTG) were used in its mutagene treatments,its superior mutant strain of L-valine was screened out through shaking culture.Result]The strain ZGH6128 was treated with 3 kinds of mutagens of UV,DES and NTG and the mutant strain JVHK597 was obtained progressively.This mutant strain possessed 5 genetic marks of Leu auxotroph,Ile auxotroph,Met auxotroph,α-AB resistance and 2-TA resistance.Under non-optimized condition,the production of acid from the strain JVHK597 reached 41.2 g/L after fermentation for 72 h.The experimental results of 8 passages showed that the acid producing ability of the strain JVHK597 was stable and its genotype was identified to be(Leu-,Ile-,Met-,α-ABr,2-TAr) and its genetic marks had stability.When the contents of bitter salt(MgSO4·7H2O) and monopotassium phosphate in fermentation medium were 0.6 and 1.4 g/L resp.,it was most beneficial for the strain to produce L-valine.Conclusion]The superior strain JVHK597of L-valine was screened out in this experiment and it provided guidance for its fermentation culture.