Researchers in Institute of Modern Physics, Chinese Academy of Sciences (IMP) obtained high titer and excellent strain of Streptomyces Avermitilis by heavy ion irradiation. By using the strain separation, purification, screening and passage, the growth characteristics of Streptomyces Avermitilis were basically grasped and the problem of strain degeneration has been preferably solved; In addition, by improving fermentation parameters, the problem of dissolved oxygen deficiency was well resolved.

The strain of Streptomyces Avermitilis obtained by heavy ion irradiation has its advancement. The Strain was put in the scale-up test of 1-ton fermentation tanks. After multi-batch fermentation, the fermentation technology is improved and the technical regulation is created. Later, the strain was put in the pilot test of 5-ton fermentation tanks which got the ideal results, that is, the fermentation titer of the  strain obtained in the test of the 5-ton tanks was higher than B1a 4600μg/ml, which has never been reported in the China and so it occupied domestic leading level.

Avermectins is a biological pesticide with many distinguishing features such as high efficiency, broad-spectrum, long validity, easy degradation and no residual. Besides, it is uneasy to produce drug-resistance. Based on these distinguishing features, it widely applied to agricultural and veterinary drug industry. The achievement is to play an important role in improving the production of avermectins, and lowering its production costs. So it has wide market prospect and the potential social and economic benefits.

RESEARCHER CONTACT:
LI Wenjian, Ph.D., Professor
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China.
Telephone: 0086 931 4969342 ; E-mail: wjli@impcas.ac.cn

5-ton tanks Fermentation Pilot Equipment (Image by IMP)