Technology Research On Fermentation Of Avermectins

Avermectin is a newly type kind of ideal biological pesticides at present.It is produced by microbial fermentation and extraction.It can kill pests or mite pests with the B1a as it′s the most activity.It is featured in broad-spectrum,high-efficiency,low-residue and the use of safety.The factors affected the biosynthesis of Avermectin by Streptomyces Avermitilis AV005 were studied.Firstly,the quality of seeds was studied.The results showed that cultivating time of one-level seed and the cultivating times of seed were the principle factors affecting the product of Avermectin.The product of Avermectin dropped largely after the seeds were cultivated over 3 times.Secondly,the optimum medium constituents were studied as follows (g/L):starch 120,Bean powder 25,yeast extract 10,CoCl₂ 0.04,CaCO₃ 0.8.Both the initial concentration of sugar and granularity of Bean powder were also the mainly factors affecting of Avermectin B₁a.Furthermore,the sucrose-added methods were studied.It was showed that it benefited to the biosynthesis of Avermectin B₁a using the method that glucose fed-rate enhanced gradually after 200h.And the potency of Avermectin B₁a improved 20%compared with the process without sucrose added.Finally,the way and the type of the stirrer were studied during the fermentation process of Avermectin B₁a.The result showed that it didn't affect the biosynthesis of Avermectin B₁a just stirring from 11h to 200h, and it would decrease energy consumption of fermentation process. Moreover,it would improve the potency of Avermectin B₁a and decrease energy consumption of fermentation process with stirrer CD-6 and A-315...