^(60)Coγ射线辐照选育阿维链霉菌及辐射效应研究

Mutation Breeding of a Streptomycin avermitlis by ^(60)Co γ-ray Irradiation and Study on Radiation Effect

[目的]采用60Coγ射线辐照选育阿维链霉菌,筛选B1a产量提高的突变菌株。[方法]用60Coγ射线作为诱变源,在辐照剂量200～1 600 Gy、剂量率10 Gy/min的条件下对一株未经任何诱变的微生物农药阿维菌素菌株Av2进行了诱变改良;对该菌株的致死率、突变率、菌落形态变化与60Coγ射线辐照剂量的关系进行了探讨,其中初筛采用抑菌圈法,复筛采用摇瓶培养发酵,阿维菌素含量测定采用高效液相色谱法。[结果]在800 Gy辐射剂量下得到了Av2-m212、Av2-m245和Av2-m286 3株高效突变菌,其Bla产量分别比原始菌株提高了36%、41%和46%,均属于皱缩型菌株。高于30%的正突变菌均在800 Gy辐射剂量下产生,该剂量点是致死率和正突变率趋于平稳的交叉点。辐照后皱缩型和火山型突变菌有正突变菌,其他形态菌株均为负突变。[结论]60Coγ射线在阿维菌素产生菌的诱变筛选中起到了重要作用,是一种非常有效的微生物诱变育种方法。

[Objective] The aim was to mutate Streptomyces avermitlis by 60Co γ-ray irradiation so as to screen mutant strain which could improve the yield of B1a.[Method] A Streptomyces avermitlis Av2 without any mutation was mutated by 60Co γ-ray irradiation under 200-1 600 Gy of irradiation-dosage and 10 Gy/min of dose-rate.The relationship among lethality,mutation dispersion,the morphological change of strains and the irradiation dosage of 60Co γ-ray were explored.The primary screening and secondary screening were carried out by inhibition zone method and bottle-shaped fermentation culture,respectively;the content of avermectin was determined by HPLC.[Result] Three mutants of Av2-m212,Av2-m245 and Av2-m286 whose B1a productions were respectively increased by 36%,41% and 46% were obtained under 800 Gy of irradiation-dosage,and they all belonged to shrinkage type.All mutations more than 30% of efficient generated under the condition of 800 Gy-dosage,and the dose was the crossing point of lethality and positive mutation dispersion which tended to be stable.After 60Co γ-ray irradiation,The shrinkage type and volcanic type mutant strains belonged to positive mutation,while the other type mutant strains belonged to negative mutation.[Conclusion] 60Co γ-ray is an effective and promising mutation method for Streptomyces avermitlis and other microorganisms.