产几丁质酶香蕉枯萎病拮抗细菌的分离鉴定及生物学特性研究

Isolation and identification of chitinase-producing bacterium biological characteristics

为了筛选出对香蕉枯萎病菌有拮抗作用的几丁质酶产生菌,以几丁质为唯一碳源进行几丁质酶产生菌筛选,然后通过平板对峙试验,从几丁质酶产生菌中筛选出1株香蕉枯萎病拮抗菌,通过形态特征和分子生物学分析,确定其为解淀粉芽孢杆菌并将其命名为DF。LB培养液测定的生长曲线显示24 h内该菌株生长达到稳定期;生物学特性数据显示该菌株在pH为5.15～8.94范围内生长良好,最佳pH为7.09;最佳碳源为甘露醇,最佳氮源为脲(尿素);拮抗试验可见病原菌菌丝发生膨大,凸起变形,原生质外漏造成菌丝中空干枯。

In order to screen chitinase-producing bacteria which could inhibit the growth of pathogen,chitinase-producing strains were isolated by screen with the chitin as sole carbon, and then ,by dual culture ,an antagonistic bacillus against Fusarium oxysporum f. sp. cubense was isolated from chitinase -producing strains.Based on morphological characteristics and the homology analysis of 16S rDNA sequence the strain was identified as Bacillus amyloliquefaciens and was named DF.DF got the stationary growth phase by cultured in LB medium in 24 h.Thc biological characteristics researches showed that DF grew well at pH 5.15 to 8.94,the optimum pH was 7.09. Mannitol was its optimum carbon source while urea was its optimum nitrogen source;The results of antagonistic mechanism study show that mycelium was enlargement,bulging deformation,protoplasm leakage and hollow withered.