米尔贝霉素A3和A4高产菌的理性选育

The rational breeding of high-yield strains for producing the single A3 and A4 components of milbemycin

目的应用理性选育理论,结合各种诱变手段,获得米尔贝霉素A4(1),A3(2)的高产菌种。方法以吸水链霉菌CGMCC7677为出发菌,通过紫外、甲基磺酸乙酯与常压室温等离子体等单独诱变或组合诱变,结合含甘氨酸、利福平、乙酸钠和3-溴丙酮酸的抗性平板进行筛选。结果通过多轮的筛选,得到米尔贝霉素突变株75-22和95-23。在不改变培养基组成和培养条件的情况下,75-22在50L发酵罐中培养360h,米尔贝霉素A4(1)的生产能力提高了5倍,米尔贝霉素A4(1)的含量也从70%提高至80%以上。95-23在50L发酵罐中培养360h,米尔贝霉素A3(2)的生产能力提高了10倍,米尔贝霉素A3(2)的含量提高至70%以上。结论主产单一组分菌种的获得,可进一步扩大米尔贝霉素的应用研究范围,也为米尔贝霉素的产业化提供了优良的菌种。

Objective To obtain high productivity of milbemycin A4 (1) and milbemycin A3 (2) using rational breeding and various kinds of mutation methods. Methods The strain Streptomyces sp. CGMCC 7677 was used as the original strain. After being mutated by a means of single or combination of UV, ethylmethane sulfonate, atmospheric and room temperature plasma(ARTP), strains werescreened in glycine-resistance, rifampicin-resistance, sodium acetate-resistance, and 3-bromopyruvate tolerance plates. Results The mutants with single component of milbemycin 75-22 and 95-23 were obtained. The productivity of milbemycin A4 (1) for 75-22 is 5 times improved compared with the initial strain CGMCC 7677 under the same fermentation conditions which run in 50L fermenter for 360h. The ratio of milbemycin A4 (1) in total components increased from 70% to more than 80%. The productivity of milbemycin A3 (2) for 95-23 is 10 times improved under the same conditions, and the ratio of milbemycin A3 (2) in total components increased from 20% to more than 70%. Conclusion More research work and application could be performed base on the new high-yield single component strains that also supply good producing stains for industry production of milbemycin.