达托霉素高产菌株选育及发酵条件优化

目的 通过对达托霉素产生菌进行诱变选育，并对其发酵条件优化，以提高其达托霉素发酵水平，降低生产成本。方法 以玫瑰孢链霉菌(DT-9#F2)为出发菌株，分别采用紫外诱变、微波诱变、LiCl诱变及复合诱变并结合链霉素抗性筛选进行菌株选育，同时，对其发酵培养基中氮源、碳源及生长因子进行优化，以进一步提高其发酵产量。结果 得到一株达托霉素高产突变株DT-37，其摇瓶发酵产量达到12.2mg/L，较出发菌株提高20.79%；优化后的发酵培养基为：酵母粉(YP300)1.65%、FeSO4 0.043%、葡萄糖1.50%、玉米淀粉7.20%、糖蜜0.72%，VB12 1.50μg/mL、硫辛酸5.00μg/mL。其摇瓶发酵产量达到30.56mg/L，较初始培养基提高了297.92%。经100L发酵罐上放大验证，达托霉素的产量达到了2872mg/L，较优化前提高了14.88%。结论 紫外、微波及LiCl复合诱变后经抗生素抗性筛选，结合发酵培养基优化，可有效提高菌株的达托霉素发酵产量。

Breeding of high daptomycin producing strains and optimization#br# of frementation conditions

Objective In order to increase the yield of daptomycin and reduce the production cost, mutation breeding of daptomycin-producing bacteria was performed, and the fermentation conditions were optimized. Methods UV-mutation, microwave mutagenesis, LiCl mutagenesis, and complex mutagenesis combined with streptomycin resistancewere used to increase the production of daptomycin from original strain of Streptomyces roseosporus DT-9#F2. Meanwhile, the nitrogen source, the carbon source, and growth factors in its fermentation medium were optimized to further increase its fermentation yield. Results A high daptomycin-producing mutantnamed DT-37 was obtained and the yield of daptomycinreached 12.2mg/L which was 20.79% higher than that of the original one. The optimized fermentation culture medium formula was yeast powder (YP300) 1.65%, FeSO4 0.043%, glucose 1.50%, corn starch 7.20%, molasses 0.72%, VB12 1.50μg/mL, and lipoic acid 5.00μg/mL. Its yield of daptomycin reached 30.56mg/L which was 297.92% higher than that of the original medium. After a scale-up experiment on a 100L fermenter, the yield of daptomycin reached 2,872mg/L, which was an increase of 14.88% compared to that before optimization. Conclusion After the original strain was subjected to ultraviolet, microwave, and LiCl compound mutagenesis and combined with antibiotic resistance screening, the selection efficiency of daptomycin could be improved eventually. After the optimizing of fermentation medium, the yield of daptomycin could be improved significantly.