中文摘要：

从辣椒根际土壤中分离筛选到对辣椒青枯病致病菌（Ralstonia solanacearum）具有较强拮抗效果而且生长速度快的菌株a45。根据生理生化特性和16S rDNA序列分析,将菌株a45鉴定为Bacillus subtilis。按照20%（V/W）的比例将a45菌液接种至等比例混合的猪粪堆肥和氨基酸有机肥中发酵4 d,制备微生物有机肥（BOF）,其中含有a45计2.0×109个g-1土。利用a45菌悬液（LC）和BOF在温室中进行了盆栽试验,盆栽土壤中接种病原菌Ralstonia solanacearum（9.6×106个g-1土）。结果表明,土壤中施用LC（1.0×107个a45 g-1土）和BOF（5‰,W/W,即1.0×107个a45 g-1土）对辣椒青枯病的防治效率分别为69.58%和76.09%,并且对辣椒生长具有显著的促进作用。土壤中施用LC和BOF能显著降低病原菌的数量,第30天时,病原菌数量较对照分别减少20.5%和25%。拮抗菌a45的数量变化显示,随着时间的延长,根际土壤中拮抗菌含量逐渐下降,但有机肥能显著延缓a45的数量下降,a45和有机肥混合使用时,根际土壤中a45的存活量明显高于a45单独使用时的存活量。初步研究表明,a45含有ituA、ituB、ituC、ituD,Qk,bam和SboA基因,分别为Iturin、Subtilisin QK、Bacillomycin和Subtilosin A的生物合成相关基因。

英文摘要：

A strain of bacterium a45,an antagonist to capsicum wilt（Ralstonia solanacearum）,was isolated from the rhizosphere of capsicum.The strain was identified as B.subtilis according to its physiological and biochemical characteristics and 16S rDNA gene sequence.20%（V/W）of a45 culture was inoculated into a mixture of pig manure compost and amino acid fertilizer,which fermented for 4 days into bio-organic fertilizer（BOF） containing about 2.0×109 g-1 soil of a45.A pot experiment was carried out in greenhouse using soil inoculated with pathogen Ralstonia solanacearum（9.6×106 g-1 soil）,and amended with either BOF（5‰ W/W,1.0×107 a45 g-1 soil） or a45 liquid culture（LC,1.0×107 a45 g-1 soil） to evaluate effect of the bio-control agents in controlling the wilt disease.Results show that the application of LC and BOF mitigated capsicum wilt incidence by 69.58% and 76.09%,respectively,and promoted growth of the plants somewhat.The population of Ralstonia solanacearum in the capsicum rhizosphere 30 days after application with LC and BOF was decreased by 20.5% and 25%,respectively compared with that in the control.And the population of a45 decreased gradually over time after inoculation in both soils.However,BOF significantly deferred the decrease as compared with LC.Besides,genes ituA、ituB、ituC、ituD、Qk、bam and sboA responsible for synthesis of antibiotics iturin,subtilisin QK,bacillomycin and subtilosin A,respectively,were detected in strain a45 with PCR,showing that the strain can be used as a biocontrol agent.