[A-HW16] Water and material transport and cycles in catchment ecosystems: from headwater to coastal area

[AHW16-05] Variation of nitrite reductase gene nirS in denitrification process

*Jun Yasumoto¹, Ryogo Takada¹, Mina Yasumoto Hirose², Takahiro Hosono³, Midori Matsunaga³ (1.University of the Ryukyus, Faculty of Agriculuture, 2.Tropical Technology Plus., 3.Priority Organization for Innovation and Excellence, Kumamoto University)

Keywords:Denitrification , Nitrite reducing genes (nirS), Real Time-PCR

This study explores the use of microbial community analysis to evaluate the processes involved in nitrate attenuation in groundwater. Real-Time PCR (Polymerase chain reaction) is used to quantify nitrite reducing genes (nirS). It is suggest that the new method for detecting denitrification activity by comparing the gene dosage that has been detected by Real-Time PCR and the value of the nitrate δ¹⁵N and δ¹⁸O is effective.This study focuses on a variation of the nitrite reductase gene (nirS) that has been detected by Real-Time PCR through at the denitrification process by the column experiment.
Acrylic column which was used in the experiment is height 70cm, an inner diameter of 7cm. The bottom of the column was packed with crushed Ryukyu limestone, the upper was filled with soil. The analysis items, in addition to the DNA copy number of nirS, was selected inorganic nitrogen (NO₃^-, NO₂^-, NH₄⁺), Total Organic Carbon (TOC), Inorganic Carbon (IC) and the nitrate δ¹⁵N and δ¹⁸O.
As a results of the column experiment, oxidative environment had been maintained at the column packed with Ryukyu limestone. On the other hand, the formation of the reducing environment had been confirmed at the column packed with soil.
The variation characteristics of the nitrite reductase gene nirS in the denitrification process was understand by column experiment. In addition, a differences as the index of denitrification between nirS and the nitrate δ¹⁵N and δ¹⁸O was revealed.