γ-聚谷氨酸高产菌株的选育及发酵条件优化

High Production Strain Breeding for γ-Polyglutamic Acid and Its Fermentation Conditions Optimization

以聚谷氨酸(γ-PGA)产生菌Bacillus subtilisHD-23为出发菌株,采用紫外线-硫酸二乙酯-亚硝基胍三因素的多组复合诱变,获得菌株Bacillus subtilisHD-F9,γ-PGA产率达到10.72 g/L,提高了56.3%,且传代稳定.对菌株Bacillus subtilisHD-F9的发酵培养基配比进行正交设计优化,并对其摇瓶培养条件进行优化,得到最佳发酵条件为:葡萄糖50 g/L,酵母膏8 g/L,谷氨酸钠40 g/L,250 mL三角瓶装液40 mL,初始pH 7.5,37℃,200 r/min,振荡培养48 h,γ-PGA产量可达14.88 g/L,提高38.8%.

Bacillus subtilis HD-23 was used as original strain for γ-PGA production, which was treated with multimutagenicity method of ultraviolet, diethyl sulfate and nitrosoguanidine. Bacillus subtilis HD-F9 was isolated, and the γ-PGA yield attained 10.72 g/L increasing by 56.3 %, and the mutant showed genetic stability during 10 generations. The fermentation medium optimized by orthogonal experiment was glucose 50 g/L, yeast extract 8 g/L, monosodium glutamate 40 g/L. In 250 mL shake flask, the optimal medium volume, temperature, original pH, rotation speed were 40 mL, 37 ℃, pH 7. 5 and 200 r/min. The final γ-PGA yield attained 14. 88 g/L increasing by 38.8 %.