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多株内生细菌。分离的内生细菌的数量和种类因植物种类不同而不同。一些植物，如茄子，在它们的组织中有许多细菌种类。相反，在一些植物中没有检测到细菌分离物。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菌株。经鉴定为荧光假单胞菌。另一方面，开展了利用内生细菌生物防治青枯病的基础调查研究。首先，研究了分离的内生细菌对青枯病的抑制效果。几个分离物显示出很高的疾病抑制水平。此外，通过使用内生细菌分离物的杀灭细胞也观察到了这种效果。这一结果表明，除抗生素生产力外，其他一些机制也参与了疾病的抑制。当在细菌种水平上鉴定出有效菌株时。从环境风险评价的角度来看，它们是对自然环境具有危险性的物种。提出了进一步分离和筛选内生细菌的必要性。针对原产于热带地区、对多种病害具有较高抗性的乡土茄子植物，进行了内生细菌的分离。因此，筛选出了一批具有抑病活性、对环境无害的内生细菌菌株。

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.