Development of utility technique and functional analysis of endophytic bacteria

从多种植物的茎和根组织中分离到50多株内生细菌。内生细菌的数量和种类因植物种类而异。一些植物如茄属植物在其组织内具有许多细菌物种。与此相反，在一些植物中没有检测到细菌分离物。阐明了植物内生细菌与植物物种之间的特定关系。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，利用内生细菌对由青枯菌引起的茄属植物青枯病进行生物防治的基础性调查研究。首先，研究了分离的内生细菌对青枯病的抑制效果。几个菌株表现出高水平的疾病抑制。此外，通过使用内生细菌分离物的杀死的细胞也观察到这种有效性。从这个结果，这表明，一些机制以外的抗生素生产力参与疾病抑制。在菌种水平上对有效分离株进行鉴定。从环境风险评价的角度来看，它们是对自然环境具有风险的物种。说明了进一步分离和筛选内生细菌的必要性。本研究以热带地区的茄属植物为研究对象，对茄属植物的内生细菌进行了分离。结果表明，从病原菌中分离到了一些对环境无危害、具有抑菌活性的内生细菌。

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.