Development of utility technique and functional analysis of endophytic bacteria

从不同植物的茎和根组织中分离到50余株内生细菌。不同植物种类分离出的内生细菌数量和种类不同。一些植物，如茄属植物，在它们的组织中有许多种细菌。与此相反，在一些植物中未检测到细菌分离物。阐明了内生细菌与植物物种之间存在着特定的关系。此外，还发现了一些对多种植物病原菌具有抗菌活性的分离物。鉴定为荧光假单胞菌。另一方面，利用内生细菌对茄枯病菌的生物防治进行了基础调查研究。首先，研究了分离的内生细菌对青枯病的抑制效果。部分分离株表现出较强的抑病作用。此外，使用内生细菌分离物的杀死细胞也观察到这种有效性。从这些结果可以看出，除了抗生素产量之外，还有其他一些机制参与了疾病抑制。当有效分离菌株在细菌种类水平上被鉴定时。从环境风险评价的角度看，它们是对自然环境有风险的物种。进一步进行内生细菌的分离和筛选是必要的。以原产于热带地区的天然茄属植物为研究对象，对其具有较高的抗病能力，对其内生细菌进行了分离。结果，分离出了一些具有疾病抑制活性且对环境无害的内生细菌。

More than 50 isolates of endophytic bacteria were isolated from stem and root tissues of various plants. The number and species of isolated endphytic bacteria were varied depending on plant species. Some plants such as Solanum sp.have many bacterial species within their tissues. In contrast to this, no bacterial isolate was detected in some plants. It is clarified that specific relationship between endophytic bacteria and plant species is existence. Moreover, some isolates which have antibiotic activity against various plant pathogenic bacteria were discovered. They were identified as fluorescent Pseudomonas. On the other hand, fundamental investigation study on biological control of bacterial wilt of solanum plant caused by Ralstonia solanacearum by using endophytic bacteria was conducted. First, effectiveness of endophytic bacteria isolated on bacterial wilt disease suppression was investigated. Several isolates indicated disease suppression at high level. Further, this effectiveness was also observed by using killed cells of endophytic bacterial isolates. From this results, it is suggested that some mechanisms other than antibiotic productivity were involved in disease suppression. When the effective isolates were identified at bacterial species level. they were risky species to natural environment from the point of view of environmental risk assessment. Necessary of more isolation of endophytic bacteria and selection were shown. Focus on native solanum plants originated from tropical regions, which have resistance to various disease at high level, isolation of endophytic bacteria was performed. As a result, some endopytic bacterial isolates which have activity of disease suppressionand no dangerous to environment were isolated.