枯草芽孢杆菌Bs916在番茄根部的定殖

摘要

In order to identify the colonization ability of Bacillus subtilis Bs916 on tomato root, the biofilm formation key gene clusters were characterized and analyzed, the biofilm formation and antagonistic activity of green fluoresent protein (GFP)⁃labelled strain Bs916G were studied, and the colonization of Bs916 was evaluated by petri dish and pot experi⁃ments. The results showed that all three key gene clusters existed in B. subtilis Bs916 genome, which were responsible for the synthesis of biofilm main constituents, exopolysaccharide ( EPS) , TasA protein and γ⁃Polyglutamic acid ( PGA) . The gene clusters were 15 715 bp ( eps) , 786 bp ( tasA) and 4 369 bp ( PGA) in sizes. Lab work revealed that GFP⁃labelled strain Bs916G and wild type had similar biofilm⁃forming ability and antagonistic effects on Ralstonia solanacearum . The a⁃mount of Bs916 colonized on tomato root was up to 3.1×107 CFU/g in MS plate.The amount of Bs916 colonized on the to⁃mato root cultured in pot fell before rising to 107 CFU/ml with or without inoculation of R. solanacearum. In conclusion, B. subtilis Bs916 has an efficient colonization in the tomato rhizosphere, which was considered the pre⁃requisite for field application of Bs916 in controlling tomato soil⁃borne diseases.%为了明确生防枯草芽孢杆菌Bs916在番茄根部的定殖能力，本研究基于Bs916全基因组数据，分析了Bs916中参与生物膜形成的关键编码基因簇，研究了Bs916及其绿色荧光蛋白（GFP）标记菌株Bs916G抑制番茄青枯菌的能力和生物膜形成能力，并采用植物MS平板定殖研究法和温室盆栽试验评估了Bs916在番茄根部的定殖能力和规律。全基因组分析结果表明，枯草芽孢杆菌Bs916拥有完整的生物膜形成关键基因（簇），包括胞外多糖（ EPS）合成酶编码基因簇、TasA蛋白和γ⁃多聚谷氨酸聚合酶编码基因簇，其大小分别为15715 bp、786 bp和4369 bp，与已报道的相关氨基酸序列同源性达96％～100％。室内试验显示，GFP标记菌株Bs916G具有和野生菌株相同的抑制番茄青枯菌的能力和生物膜形成能力。在 MS平板试验中，Bs916在番茄根部的定殖量可达3．1×107 CFU／g。盆栽试验结果显示，在常规土壤或接种青枯菌处理中，Bs916在番茄根部的定殖数量都呈现先下降后上升，最后趋于稳定的趋势。表明，枯草芽孢杆菌Bs916可以在番茄根部有效定殖，这为其在田间防治番茄青枯病提供重要保障。