魔芋软腐病拮抗放线菌的筛选及其抑菌活性研究

Screening of Antagonistic Actinomyces to Erwinia carotovora and Study on Its Antibacterial Activity

[目的]从土壤中分离筛选魔芋软腐病拮抗放线菌,测定其发酵抑菌活性,并对其活性成分进行初步分离。[方法]采用平板对峙培养法筛选出魔芋软腐病拮抗放线菌。对活性较强的拮抗菌株SJK18作不同碳源、氮源、温度及pH值等培养条件的单因素试验,并分别测定其发酵液的抑菌活性。分别用乙醇和乙酸乙酯萃取拮抗菌的发酵液,并测定抑菌活性。[结果]共分离得到112株放线菌,其中11株具有抑菌能力。在以玉米粉为碳源、KNO3为氮源、温度为30℃及pH值为6.0的单因素试验条件下,SJK18发酵液的抑菌活性最强,且活性的pH值适应范围在5.5～10.0。乙醇提取物的抑菌圈直径为17.0mm。乙酸乙酯萃取浓缩液无抑菌活性,而其萃余液抑菌圈直径为20.0mm。[结论]筛选获得1株对魔芋软腐病原菌有较强拮抗作用的放线菌。

[Objective]The aim was to screen antagonistic actinomyces from the soil against konjac soft rot,and detect its fermentative antibacterial activity and preliminarily separate its active components.[Method]Use the dual culture to primarily screen antagonistic actinomyces against konjac soft rot.The single-factor tests of the SJK18 strain,with strong activity,in different carbon sources,nitrogen sources,temperatures and pH were carried out and the strain＇s fermentative antibacterial activities were detected respectively.The strain＇ fermentation broths were extracted with alcohol and acetic ester and detected their antibacterial activities.[Result]112 strains were obtained in all and 11 of them had antibacterial activity.The SJK18 strain＇s antibacterial activity were best in corn powder as the carbon sources,KNO3 as the nitrogen source,at 30 ℃ and at pH6.0 in the single-factor tests,and its active pH range was from 5.5 to 10.The inhibition zone diameters of alcohol extract and raffinate of ethyl acetate were 17.0 mm and 20.0 mm separately,while the concentrated solution of ethyl acetate had no antibacterial activity.[Conclusion]A strain of actinomyces whit strong antibacterial activity against konjac soft rot was obtained.