Molecular biological analysis of the nitrogen-fixation ability of Sphingomonas paucimobilis

点击翻译按钮获取中文摘要

Modern agriculture relies on large amount of chemical nitrogen fertilizer. This dependence has led to environmental eutorophicaton and consumption of much fossil fuel which causes environmental impact such as the promotion of global warming. To improve this tendency of modern agriculture, we are planning the continuous supply of nitrogen source in the field by taking advantage of biological nitrogen fixation. A diazotroph in genus Sphingomonas (Sphingomonas paucimobilis Y39) was isolated form rice rhizosphere. Afterward, it was discovered that may Sphingomonas bacteria are present on the surface of rice leaves or in rice plants. I expected that S.paucimobilis Y39 could be an endophyte of rice and provide efficient nitrogen to rice from both sides of the rice rhizosphexe and in plant by biological nitrogen fixation.At present, Sphingomonas paucimobilis Y39 was renamed Sphinomonas azotifigens Y39. At the beginning, I aimed to introduce the GFP gene into S.azotifigens Y39 for the purpose of demonstration of its presence in rice plants, i.e. demonstration of endophytic ability of S.azotifigens Y39. However, transformation of this bacterium was difficult and I have not obtained a GFP-expressing transformant. Thus, I started to isolate other endophytic Sphingomonas diazotrophs from flag leaves of rice, expecting that the obtained Sphingomonas bacteria will be easy to introduce the GEP gene. However, I have not yet isolated Sphingomonas diazotrophs.