关键词: 反硝化, N2O, 荧光定量PCR, 启动子, 转录活性

Abstract: At present, the release of N2O in sewage denitrification process increases year by year. Lots of N2O cause greenhouse effect, acid rain and destroying the ozone layer. In order to study the mechanism of N2O releasing during denitrification, online bioinformatics software was used to predict the promoter-related information of four  denitrifying enzyme genes of Sinorhizobium sp. NP1. It has been predicted that the gene expression of the four key enzymes required for the denitrification process do not use the same promoter, but four different promoters. Meanwhile，the promoters of nitrate reductase and nitrite reductase are strong, while promoters of nitric oxide reductase and nitrous oxide reductase are weak. In order to explore the above prediction results, we used real-time PCR to detect the difference in transcription levels of four denitrifying genes in Sinorhizobium sp. NP1 cultured with KNO3 as the sole nitrogen source. And we measured the content of metabolites produced during denitrification. It was found that the transcription levels of nitrate reductase gene and nitrite reductase gene were significantly higher than those of nitric oxide reductase gene and nitrous oxide reductase gene. And there was a lot of N2O in the denitrification process. We speculated that it may be related to the strength of different promoters. Therefore, the expression of denitrifying enzymes can be regulated by genetic engineering such as transformation of operons, which lead all N2O reduced to N2 and then released into the air. In a word, building more efficient and less polluted denitrifying bacteria has profound social ecological significance.

Key words: denitrification, N2O, real-time PCR, promoter, transcriptional activity