烟草疫霉拮抗菌株P 72 10的鉴定及其拮抗代谢 产物 初步分析

 为探讨烟草根际生防细菌的生防机制，从重庆地区连作烟田健康烟株根际土壤中分离筛选到1株对烟草疫霉具有较强拮抗作用和对黑胫病具有良好防效的细菌菌株P-72-10。根据培养性状、形态特征、生理生化特性、基因组DNA的(G+C)mol%含量测定以及16S rDNA基因序列分析确定该菌株的分类地位。该菌株菌落乳白色，能产生水溶性荧光色素，革兰氏染色反应阴性，菌体杆状、大小(8.1~16.2)μm×(1.8~4.8)μm，单端生鞭毛，不形成芽孢。The BIOLOG GN2 结果显示该菌株属于假单胞菌属Pseudomonas。该菌株基因组DNA的(G+C)mol%含量为 60.72 mol%。16S rDNA基因序列分析显示该菌株与假单胞菌属荧光假单胞杆菌多个菌株的序列同源性达到99%，GenBank上的登录号为：HQ888871。结合其形态特征和生理生化特性，将菌株P-72-10鉴定为荧光假单胞杆菌P. fluorescens。平板检测拮抗代谢产物结果表明：该菌株具有分解纤维素、蛋白质和结合Fe ³⁺的能力，但不能分解几丁质。

Identification and characterization of antagonistic bacterial strain P-72-10 against Phytophthora nicotianae

Tobacco black shank,caused by Phytophthora nicotianae van Breda de Haan,is one of economically important disease of tobacco production.In the previous study,a strain P-72-10 was isolated from the healthy tobacco in the rhizosphere soil of Chongqing.It was selected based on its strong antagonistic activity against P.nicotianae on the plate dual-culture test and its ability to suppress tobacco black shank disease effectively in the greenhouse condition.In the study,the phylogeny of P-72-10 was analyzed,and its taxonomic position was identified using morphological and chemotaxonomic characteristics,together with 16S rDNA gene phylogenetic analysis.The colonies were cream in color on KB culture.Cells were gram-negative,rod-shaped (8.1-16.2)μm×(1.8-4.8)μm],motile owing to one or several polar flagella and did not form endospores.The growth temperature for P-72-10 ranged from 4 to 40℃ with the optimum at 28-30℃.The results of BIOLOG GN2 showed that P-72-10 belonged to Pseudomonas.The genomic(G+C) content was 60.72%.Phylogenetic analysis of the 16SrDNA gene sequence revealed that P-72-10 was the most closely related to P.fluorescens,with the sequence similarity of 99%.Nucleotide number of the accession was HQ888871.Taxonomically,strain P-72-10 was identified as P.fluorescens.On the plate culture,strain P-72-10 produced proteinase,celluase,and siderophore,but not chitinase.