螺旋霉素高产菌种的推理选育

Rational selection of high producing strain of spiramycin

根据螺旋霉素的生物合成途径对螺旋霉素产生菌产二素链霉菌进行推理选育，并获得了高产菌种。首先在紫外线诱变的基础上，筛选豆油耐性变株，得到菌株ＸＣ２－３７，其发酵效价较出发菌株ＸＣ１－２９提高９％。通过培养基优化，菌株ＸＣ２－３７的发酵效价提高６１．８％。再以紫外线处理菌株ＸＣ２－３７，并筛选缬氨酸诱导变株，得到菌株ＸＣ３－１１，其发酵效价较菌株ＸＣ２－３７提高２０％。菌株ＸＣ３－１１经自然分离得到菌株ＸＣ４－１８，发酵效价达到４５００ｕ／ｍｌ，为原始出发菌株ＸＣ１－２９的２．２５倍。传代试验表明菌株ＸＣ４－１８的高产遗传特性稳定。菌株ＸＣ４－１８应用于５０ｍ３发酵罐进行工业化生产，与原始出发菌株ＸＣ１－２９相比，发酵效价和发酵指数分别提高８４．９％和４３．６％。

The biosynthetic pathway of spiramycin was used for rational selection of spiramycinproducing strain Streptomyces ambofaciens. Firstly when the monospore suspension of S.ambofaciens XC129 was treated with UV, we screened the oil tolerant mutant strains on the agar plates containing oil, and gained a strain XC237, its potency increased by 9% over the parent strain XC129. The productivity of strain XC237 was raised 61.8% by culture medium improvement. Then, we treated the monospore suspension of strain XC237 with UV, selected the valine induced mutant strains on the agar plates containing Lvaline, and obtained a strain XC311, whose potency increased by 20% over the parent strain XC237. Finally, we got a strain XC418 by natural selection of strain XC311. The productivity of strain XC418 reached 4500u/ml, which was 2.25 times as much as that of the original strain XC129.Subculture test indicated that the hereditary character of strain XC418 was stable. The fermentation of strain XC418 was performed in 50m3 fermentation tank and compared with that of the original strian XC129, it made the potency and index of fermentation increased by 84.9% and 43.6%, respectively.