黄瓜枯萎病拮抗放线菌S24的分离、鉴定及发酵条件优化

Isolation,Identification and Fermenting Condition Optimization of Antagonistic Actinomycetes S24 against Fusarisum oxysporum f.sp.cucumebrium

为了筛选黄瓜枯萎病拮抗放线菌,从蔬菜温室大棚及附近土壤中分离了59株菌落形态有差异的放线菌,通过平板对峙筛选试验,获得2株对黄瓜枯萎病菌抑菌率在60%以上的放线菌,分别是S21和S24,其中S24的抑菌率达到74%。根据形态特征、生理生化特性和分子分类测定结果,初步将S24鉴定为黄麻链霉菌(Streptomyces corchorusii)。选用7种常用的放线菌发酵培养基对S24进行发酵,7d后测定发现,5号培养基发酵上清液对黄瓜枯萎病菌的抑制活性最强,抑菌率达到59.44%,其细胞破碎液对黄瓜枯萎病菌的抑菌率为39.76%。通过比较发现,75mL为放线菌S24的最适发酵装液量(250mL三角瓶)。采用正交试验优化后的培养基进行发酵,获得的上清液及细胞破碎液对黄瓜枯萎病菌的抑菌率分别达到76.14%、52.27%,较优化前分别提高了14.64、10.11个百分点。

To screen antagonistic actinomycetes against Fusarisum oxysporum f.sp.cucumebrium （F.o.c）,fifty-nine actinomycetes showing difference in morphology were isolated from greenhouse and surrounding soils through plate cultivation,and among them two strains,S21 and S24,with the inhibition rate over 60%,were acquired.The inhibition rate of S24 to F.o.c reached 74%. Combined with morphological characteristics,physiological and biochemical properties and molecular determination results,S24 was preliminarily identified as Streptomyces corchorusii. Seven commonly used fermentation media were selected for screening,and the result showed that the supernatant of No.5 medium after 7-day fermentation displayed strongest inhibition activity to F.o.c with the inhibition rate reaching 5 9.44%,meanwhile the inhibition rate of the debris＆amp;nbsp;reached 39.76%.The optimum volume of fermentation medium was 75 mL in 250 mL flask for S24.Through optimization of No.5 medium by orthogonal design,the optimum fermentation medium composition of S24 was found,and the inhibition rates of the fermentation supernatant and debris of S24 to F.o.c reached 76.14% and 52.27%,increased by 14.64,10.11 percentage points,respectively.