银杏内生细菌的分离鉴定及抑菌活性初探

【目的】从银杏(Ginkgo biloba)茎叶中分离鉴定内生细菌, 测定其体外抑菌活性及对辣椒果疫病的防治效果。【方法】采用平板对峙法筛选出对辣椒疫霉菌(Phytophthora capsici)有拮抗作用的内生细菌, 并用平板对扣法测定其中一株防治效果较好的内生细菌产生的挥发性物质对辣椒疫霉菌生长的影响。通过生防菌液和病原菌孢子悬浮液喷雾接种辣椒果测定该菌株对辣椒果疫病的防治效果。基于形态特征、生理生化特性、16S rDNA和gyrA基因序列同源性分析鉴定该生防菌株。【结果】从银杏的茎和叶中分离获得9株内生细菌。平板对峙生长试验结果表明, 菌株W5对供试的辣椒疫霉菌、稻瘟病菌(Pyricularia grisea)、水稻纹枯菌(Rhizoctonia solani)、黄瓜枯萎病菌(Fusarium oxysporum)、荔枝霜疫霉菌(Peronophythora litchi)、荔枝酸腐菌(Geotrichum candidum)均有抑制作用, 其中对辣椒疫霉菌、稻瘟病菌和荔枝霜疫霉菌的抑菌效果显著, 抑菌率分别为88.9%、86.3%和90.2%。其产生的挥发性物质能明显抑制辣椒疫霉菌菌丝的生长。对辣椒采后果疫病的防治效果表明, 先喷雾接种W5菌悬液24 h后再接种辣椒疫霉病菌孢子悬浮液的防治效果最好, 可将辣椒果的保鲜期延长2?3 d。该菌株被鉴定为解淀粉芽胞杆菌(Bacillus amyloliquefaciens)。【结论】获得了一株对植物病原菌物有良好防治效果的银杏内生解淀粉芽胞杆菌W5, 对辣椒采后果疫病及其他病原真菌的防治具有潜在应用价值。

Isolation and identification of endophytic bacterial strains from Ginkgo biloba and their antimicrobial activities

Objective] To isolate and identify biocontrol bacterial strains from Ginkgo biloba and evaluate their inhibition to Phytophthora capsici in vitro and control efficacy against fruit phytophthora blight of pepper. Methods] The method of dual culture on agar plate was used for screening the antagonistic endophytic bacteria against P. capsici, and the inhibition effect of the volatile substances from a better control effect strain on P. capsici was tested by two-sealed-base-plates method. Control efficacy against pepper phytophthora blight was evaluated by spraying bacterial cultures on capsicum fruits. The identification of bacterial strains was based on morphological, physiological, biochemical characteristics and phylogenetic analysis of 16S rDNA and gyrA gene sequences. Results] Nine endophytic bacterial strains were isolated from healthy stems and leaves of Ginkgo biloba. Among them strain W5 was selected for further study, which had antagonistic action against P. capsici, Pyricularia grisea, Rhizoctonia solani, Fusarium oxysporum, Peronophythora litchii, Geotrichum candidum on agar plates, especially to P. capsici, P. grisea and P. litchi, the inhibitory rates were prominent with 88.9%, 86.3% and 90.2%, respectively. The volatile substances produced by strain W5 could significantly inhibit the mycelia growth of P. capsici. The control results of fruit phytophthora blight of pepper by strain W5 showed that it could get better protective efficacy when the spore suspension of the pathogen was inoculated 24 h after spraying inoculation with strain W5. And spraying strain W5 could also prolong the fresh period of pepper fruits to 2?3 d than the control. The strain W5 was identified as Bacillus amyloliquefaciens. Conclusion] An antagonistic B. amyloliquefaciens strain W5 was obtained, and it had potential for the biological control of fruit phytophthora blight of pepper and other pathogenic fungal diseases.