水生植物の根圏土壌における硝化・脱窒に及ぼす菌根菌の影響とその微生物機構

[Effects of Mycorrhizal Fungi on Nitrification and Denitrification in the Rhizospheric Soil of Aquatic Plants and Its Microbial Mechanism].

• Duo Liu
• Lei Wang
• Zhan-Bo Cao
• Hao Duan

抄録

水生植物の根圏土壌における硝化脱窒に及ぼす菌根菌接種の影響を調べるために、地元の土壌から得られた菌株MF-MDを接種した。接種していない植物を対照群とした。水生植物を水中窒素富栄養化条件下で3ヶ月間培養した後、根圏土壌中の硝化・脱窒活性を測定した。その結果、MF-MDを接種することで、両植物の根圏土壌における硝化が促進された。一方、MF-MDを接種した植物は根圏土壌で脱窒を促進したが、MF-MDを接種した植物は根圏土壌で脱窒を阻害した。 根圏土壌の微生物バイオマス中の硝化菌と脱窒菌の群集構造の変化を測定することで、土壌の硝化-脱窒活性のメカニズムを解析した。その結果、実験群の根圏土壌微生物バイオマス（SMB）は対照群よりも高く、土壌の硝化・脱窒に関連する微生物群集構造の変化が群間で異なることがわかった。本研究は、水生植物と組み合わせた菌根菌が富栄養化水中の窒素含有量を除去する方法の理解に貢献するものである。

To investigate the effect of mycorrhizal fungi inoculation on nitrification-denitrification in the rhizospheric soil of aquatic plants, and were inoculated with the strain MF-MD obtained from local soil. Uninoculated plants served as the control group. The plants were cultivated for 3 months under nitrogen eutrophication in water, and then the nitrification and denitrification activities in the rhizospheric soil were determined. The results showed that inoculation with MF-MD promoted nitrification in the rhizospheric soil of both plants. However, MF-MD inoculation promoted denitrification in the rhizospheric soil of but inhibited denitrification in the rhizospheric soil of . The mechanism of soil nitrification-denitrification activity was analyzed by measuring the changes in the community structure of nitrifying bacteria and denitrifying bacteria in the microbial biomass of the rhizospheric soil. It was found that the rhizospheric soil microbial biomass (SMB) of the experimental group was higher than that of the control group and that the changes in the microbial community structure related to soil nitrification and denitrification differed between groups. This study contributes to an understanding of how mycorrhizal fungi combined with aquatic plants can remove N content in eutrophic water.