纳他霉素产生菌的诱变育种及其发酵条件的优化

Mutation breeding and optimization of fermentation for high production of natamycin by Streptomyces natalensis

目的以纳塔尔链霉菌(Streptomyces natalensis)SIPI-NHF-09为出发菌株进行诱变选育和培养条件优化,以提高其纳他霉素的产量。方法采用紫外和微波结合对纳塔尔链霉菌SIPI-NHF-09进行诱变选育,并对获得的高产突变株SIPI-UW-10-22的发酵条件进行了初步优化。结果经过连续3轮的紫外和微波诱变,获得高产突变株SIPI-UW-10-22,其纳他霉素(Natamycin)产量达到3.15g/L,是出发菌株的3.5倍,且该菌株经多次传代,遗传性能稳定。对SIPI-UW-10-22发酵条件优化后获得其发酵条件为:以5.5%玉米淀粉加0.5%葡萄糖为碳源,2%黄豆饼粉加1%酵母粉为氮源,种龄46h,初始pH7.0,接种量8%,摇床转速220r/min,28℃培养126h。此条件下,纳他霉素的产量达到4.07g/L,较优化前提高了1.29倍。结论紫外与微波诱变相结合的方法简便有效,所获得高产菌株遗传性状稳定。

Objective The mutation breeding and cultural conditions optimization were used to obtain a higher natamycin-producing strain. Methods A high-yield Streptomyces natalensis mutant strain SIPI-UW-10-22 was obtained after breeding SIPI-NHF-09 by ultraviolet and microwave mutation, and it was genetic stable for 5 generations. The fermentation conditions of SIPI-UW-10-22 was also optimized. Results After three rounds continuous selection, the yield of mutant strain SIPI-UW-10-22 reached 3.15g/L, which was 3.5 times higher than the parent strain SIPI-NHF-09. The optimal fermentation conditions were as follows： 5.5% corn starch plus 0.5% glucose as compounded carbon sources, 2% soybean cake powder plus 1% yeast powder as compounded nitrogen sources, seed age 46h, initial pH7.0, inoculum quantity 8%, rotating speed 220r/min, culture temperature 28~C, fermentation time 126h. Under this condition, 4.07g/L natamycin was obtained, which was 1.29 times higher than that under the initial conditions. Conclusion Ultraviolet combined with microwave mutation can be an effective breeding method, by which the high-yield mutant strain obtained was genetic stable.