猕猴桃溃疡病菌拮抗菌筛选、鉴定及发酵条件优化

目的:从不同地区猕猴桃根际土壤中筛选拮抗猕猴桃溃疡病菌的菌株,优化其产生抑菌活性物质的发酵条件,为猕猴桃溃疡病的生物防治提供潜在的资源菌。方法:采用平板稀释法从猕猴桃根际土壤中分离获得菌株,采用抑菌圈法筛选拮抗菌;通过形态学特征、生理生化特征及16S rDNA序列分析对其进行鉴定;并采用单因素及正交试验优化培养基组分及发酵条件。结果:从土壤中共分离到288株放线菌,其中编号为NA-TXL-1的菌株对猕猴桃溃疡病菌的拮抗效果最佳,采用预防法、治疗法进行盆栽实验,发酵原液的防治效果分别为73.06%、55.62%,初步鉴定该菌株为抗生链霉菌。其最佳发酵配方和培养条件为:乳糖30 g/L、酵母粉3 g/L、NaCl 1 g/L、K_2HPO_4 0.5 g/L、MgSO_4·7H_2O 0.5 g/L、FeSO_4 0.01 g/L,种子培养基为乳糖-酵母粉培养基,接种量为2%,起始pH值为7.0,发酵原液、上清液、重悬液分别培养5、14、5 d。结论:经鉴定,拮抗菌株为Streptomyces antibioticus。在优化的发酵条件下,该菌株对猕猴桃溃疡病菌具有更好的拮抗效果。

Screening,Identification and Optimization of Fermentation Conditions for Antagonistic Actinomycetes against Pseudomonas syringae pv. actinidiae

Aims: To isolate and screen the antagonistic strains with inhibitory activity against Pseudomonas syringae pv. actinidiae from a soil sample collected from the rhizosphere of kiwifruit in different areas and to optimize the fermentation conditions for enhanced production of antibacterial substances. Methods: Antagonistic strains were isolated by pour plate method, screened by inhibition zone method, and identified by morphological, physiological and biochemical characteristics and 16S rDNA sequence analysis. The optimal medium composition and fermentation conditions were optimized by one-factor-at-a-time and orthogonal array design methods. Results: A total of 288 actinomycetes strains were isolated, among which strain NA-TXL-1 exhibited the strongest inhibitory activity against Pseudomonas syringae pv. actinidiae. The effects of the fermentation broth in preventing and controlling Pseudomonas syringae pv. actinidiae in pot cultivated plants were 73.06% and 55.62%, respectively. Strain NA-TXL-1 was identified as Streptomyces antibioticus. The seed medium, inoculum size and initial pH value were optimized to be lactose-yeast power culture medium, 2%; and 7.0, respectively. The optimal culture medium consisted of 30 g/L lactose, 3 g/L yeast powder, 1 g/L NaCl, 0.5 g/L K2HPO4, 0.5 g/L MgSO4·7H2O, and 0.01 g/L FeSO4 at initial pH of 7.0. The optimal culture times for harvesting fermentation broth, the supernatant, and re-suspension were 5, 14, and 5 days, respectively. Conclusions: Strain NA-TXL-1 was identified as Streptomyces antibioticus, exhibiting stronger antagonistic effect under optimized fermentation conditions.