黄瓜枯萎病生防芽孢杆菌的定向筛选及其抑菌活性物质特性分析

研究拟从北京郊区黄瓜根际土壤中定向筛选黄瓜枯萎病菌生防芽孢杆菌,并研究其抑菌活性物质的基本特性。采用热处理和形态观察结合平板对峙法定向筛选黄瓜枯萎病菌拮抗菌。从北京郊区黄瓜根际土壤中定向分离到63株产芽胞的菌株,从中筛选到2株对黄瓜枯萎病菌（Fusarium oxysporium f.sp.cucumarinum Owen.）具有较好拮抗作用的菌株,命名为j-28和j-50。拮抗菌j-28对黄瓜枯萎病菌的抑菌带达到11.0 mm。此外,拮抗菌j-28有较广的抑菌谱,对黄瓜灰霉病菌（Botrytis cinerea）、马铃薯干腐病菌（Fusarium sulphureum）和茄子黄萎病菌（Verticilllium albo-atrum）等具有很强的拮抗作用。经过形态观察、理化分析和分子鉴定,j-28和j-50鉴定为枯草芽孢杆菌（Bacillus subtilis）。研究还发现拮抗菌j-28的发酵液经过高温和强酸碱处理后抑菌效果会明显减弱,说明拮抗菌j-28产生的主要抑菌活性物质可能是蛋白类。笔者定向筛选到针对北京郊区多发的黄瓜枯萎病菌拮抗菌枯草芽孢杆菌j-28,具有潜在的应用价值,为今后北京郊区黄瓜枯萎病菌的防治提供新的生物防治资源。

Oriented Screening Antagonistic Bacillus against Fusarium oxysporium f.sp. cucumarinum Owen and Analysis the Character of its antifungal agents

This study was to oriented screen antagonistic Bacillus against Fusarium oxysporium f. sp. cucumarinum Owen and analyze the character of its antifungal agents. Heat treatment and morphological observation combining flat confrontation culture method was used to oriented screen antagonistic Bacillus against Fusarium oxysporium. Sixty three isolates of spore-producing bacterial strains were isolated from the rhizosphere soil of protected continuous cropping cucumber. Among them, two strains, named as j-50 and j-28, were found to have high antifungi activities against Fusarium oxysporium. Especially, strain j-28 had an inhibition zone of 11.0 mm against Fusarium oxysporium. Furthermore, strain j-28 also had high antagonistic effects on other plant pathogenic fungi. The strain j-28 was identified as Bacillus subtilis by physiolofical characteristics, biochemical, morphological, as well as the 16S rDNA sequence analysis. This study showed that antifungal activities of strain j-28 were significantly affected by heat and acid-base treatment, which may suggested that the antifungal agents of strain j-28 may be protein. Bacillus j-28 with high antifungal activities and its special characters can be a potential biological control source of Fusarium oxysporium.