Breeding of L-valine producing strain JVHK597 and influence of inorganic salt on its acid production__ | L-缬氨酸产生菌JVHK597的选育及无机盐对其产酸量的影响__

Chinese. ［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。_

English. ［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.