拮抗辣椒疫霉菌海洋细菌菌株SH-27的筛选鉴定及其防病促生作用

【背景】由辣椒疫霉引起的辣椒疫病是全球辣椒生产中一种毁灭性的病害。近年来生物防治因其具有对环境友好、对人畜安全的特性而倍受关注。【目的】筛选对辣椒具有防病促生作用的海洋细菌菌株SH-27并鉴定其分类地位。【方法】采用稀释分离法和平板对峙法筛选拮抗辣椒疫霉菌的海洋细菌菌株,以发酵液灌根法测定海洋细菌SH-27菌株对辣椒盆栽的防病促生作用;通过形态特征、生理生化测试及多基因序列分析对海洋细菌SH-27菌株进行鉴定。【结果】从分离的142株海洋细菌中筛选获得11株对辣椒疫霉菌具有较强抑制作用的细菌菌株,其中以来自珊瑚的SH-27菌株的抑菌作用最强、抑菌谱广;室内盆栽试验结果表明,SH-27菌株发酵液处理后的辣椒植株根长、株高、茎粗、鲜重、干重均显著高于对照处理。SH-27菌株发酵液灌根处理后,对辣椒疫病4、6和9 d的防效分别为70.81%、66.55%和48.20%。经形态特征、生理生化测试及16S rRNA、gyrA基因序列分析,鉴定SH-27菌株为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。【结论】海洋细菌SH-27菌株对辣椒具有较好的防病促生效果,具有开发为微生物农药及菌肥的潜力。

Screening and identification of a marine bacterium strain SH-27 against phytophthora capsici causing pepper phytophthora blight

Background] Pepper Phytophthora blight, caused by Phytophthora capsici, is one of the most devastating diseases of pepper growing areas worldwide. Biological control has drawn more and more attention in recent years for its safety to environment, human and animal. Objective] To screen and identify a marine bacterium strain SH-27 against phytophthora capsici and study its effects on disease control and growth promotion on pepper. Methods] Antagonistic marine bacteria were isolated by serial dilution and dual culture. The effects of controlling disease and growth promotion on pepper seedlings were studied by using the fermentation broth of strain SH-27. Strain SH-27 was identified by morphological characteristics, physiological and biochemical tests and 16S rRNA and gyrA gene sequence analysis. Results] A total of 142 bacterial isolates were obtained. Among them, 11 strains displayed the antagonistic activity to Phytophthora capsici. Especially strain SH-27 isolated from corals displayed high antagonistic activity and broad antimicrobial spectrum. Pot tests showed that the root length, plant height, stem diameter, fresh weight and dry weight of pepper plant treated with SH-27 fermentation broth were promoted significantly when compared to the control treatment. The control efficacy of strain SH-27 to pepper phytophthora blight were 70.81%, 66.55% and 48.20% when the pathogens were inoculated after 4, 6 and 9 days respectively. Based on characteristics in morphology, physiology, biochemistry, 16S rRNA and gyrA gene sequence analysis, strain SH-27 was identified as Bacillus amyloliquefaciens. Conclusion] Due to its effects of disease control and growth promotion on pepper, strain SH-27 is possible to be further developed as an excellent strain for microbial fertilizer and fungicide.