玉米大斑病生防放线菌的筛选鉴定及发酵条件优化

Screening,identification and optimization of fermentation conditions of an antagonistic actinomycetes strain to Setosphaeria turcica

【目的】从土壤中筛选对玉米大斑病菌具有较强拮抗作用的放线菌菌株。【方法】采用稀释涂布法分离;采用平板对峙法、牛津杯法、抑制菌丝生长速率法、抑制孢子萌发法进行拮抗菌的筛选;根据菌株BZ45的形态与培养特征、生理生化特性、16SrDNA序列分析对其进行鉴定。通过单因素试验和正交设计试验优化培养基组分及发酵条件。【结果】通过分离筛选得到一株具有强抑制作用的放线菌菌株BZ45,它对常见的8种病原真菌均有拮抗作用,菌株BZ45的发酵滤液对玉米大斑病菌(Setosphaeria turcica)CC9的菌丝生长和孢子萌发均有较强的抑制作用。菌株BZ45与链霉菌中的壮观链霉菌(Streptomyces spectabilis)的亲缘关系较近,且形态与培养特征、生理生化特性与壮观链霉菌的基本相符。研究表明其最佳发酵配方和培养条件为:果糖1.5%、蛋白胨3.0%、KH2PO40.1%、NaCl 0.04%、CaCO30.1%,起始pH为7.2,装瓶量50 mL/250mL,28℃,200 r/min,种子液接种量为10%,摇瓶培养4 d。【结论】菌株BZ45鉴定为壮观链霉菌(Streptomyces spectabilis),菌株BZ45对玉米大斑病菌(Setosphaeria turcica)CC9显示出较强的拮抗作用。

[Objective] To isolate and screen antagonistic actinomyces strains with inhibitory activity on Setosphaeria turcica from soil.[Method] Actinomycetes were isolated by Pour Plate method.Antagonistic actinomycetes were screened by confrontation culture,cylinder plate,suppression of mycelial growth and spore germination method in vitro.Strain BZ45 were identified by morphological,cultural,physiological and biochemical characteristics and 16S rDNA sequence analysis.The fermentation condition was optimized by single factor and orthogonal experiment.[Result] Strain BZ45 showed antagonistic to 8 plant pathogens.Its filtrate inhibited the mycelial growth and spore germination of Setosphaeria turcica CC9.Strain BZ45 belonged to Streptomyces spectabilis.The optimum culture conditions of strain BZ45 were with a medium of 1.5% fructose,3.0% peptone,0.1% KH2PO4,0.04% NaCl,0.1% CaCO3 at initial pH of 7.2,liquid volume 50 mL in 250 mL flask,200 rpm at 28℃,inoculation size of 10% for 4 d.[Conclusion] Strain BZ45 was identified as Streptomyces spectabilis and antagonistic against Setosphaeria turcica CC9.