一株产谷氨酸菌株的复合诱变选育及突变株的生物学特性

对产谷氨酸的谷氨酸棒杆菌(Corynebacterium glutamicum)进行以硫酸二乙酯(DES)和紫外线(UV)相结合的复合诱变,经选育得到一株高产突变株LG - 01.将其接种在含葡萄糖初始浓度为150.0 g/L,初始pH值为7.2～7.6的液体培养基中,于30℃下培养48 h后,其谷氨酸产量达到106.10 g/L,比原始菌株提高了25.74％(同等条件下,原始菌株的谷氨酸产量为84.38 g/L).对该突变株的产谷氨酸代谢特性进行研究,结果表明:其最适初始pH值为7.2,最佳培养温度为30 ℃,以葡萄糖为最佳碳源,其谷氨酸产量最高时相应的葡萄糖浓度为150.0 g/L,其某些生物学特性发生了改变,如延迟期变长,对数期的细胞生长能力较强,对底物的利用率比原始菌株约提高5％等.

Compound mutation of a glutamic acid-producing strain and biological qualities of the mutant

DES and UV were respectively used to mutagenize the fermentative glutamic acid-producing strain Corynebacterium glutamicum to improve its production ability.Then a high-yield mutant named as LG-01 was obtained,which has stable glutamic acid production ability tested in several batch fermentation experiments.Under glucose’s initial level of 150.0 g/L in the fermentative medium,initial pH 7.2～7.6,incubating temperature 30℃ and one culturing period of 48 h,its cumulative glutamic acid yield arrived to 106.10 g/L,the percentage of 25.74 higher approximately than the corresponding yield of the original strain(Under the same culturing conditions as the mentioned above,the value was only about 84.38 g/L).On the other hand,in the experiment,the optimum cultivating conditions of glutamic acid production for the mutant were also explored.The testing result showed that the optimal parameters on metabolism of glutamic acid were as follows: initial pH 7.2,incubating temperature 30 ℃,the optimum carbon source being glucose,and its optimal level being 150.0 g/L when the yield of glutamic acid arrived to the biggest one.Compared to the original strain’s growth qualities,the ones of the mutant were markedly different,for example,the growth lag phase of the mutant being expanded,its growth ability during the log phase improved than that of the former and the utilization rate of substrate for the mutant approximately increasing by 5%,etc.The data mentioned above indicated that DES-UV compound mutation was successful and potential in the production of glutamic acid.