| In order to reveal the relationship between denitrification process and environmental factors in the Liaohe estuary,the sediments samples were collected in May 2014,and the nitrite reductase gene(nirS,nirK)and nitrous oxide reductase gene(nosZ)were used as molecules The abundance and diversity of nitrite reductase gene and nitrous oxide reductase gene in sediments were measured by real-time quantitative PCR and illumina Miseq high-throughput sequencing.The results of real-time quantitative PCR showed that the abundance of nirS gene in Liaohekou sediments was 5.61 × 105 copies / g to 3.67 × 107 copies / g,and the gene abundance of nirK was 1.47 × 105 copies / g to 5.61 × 106 copies / g,The gene abundance of nosZ was 1.44 x 103 copies / g to 1.37 x 106 copies / g.The abundance of different functional genes is affected by different environmental factors.There was no significant correlation between nirK gene abundance and salinity and other environmental factors.The abundance of nirS gene was negatively correlated with salinity(P = 0.008,r = 0.924),and positively correlated with NO2-(P = 0.007,r = 0.93).The abundance of nosZ gene was negatively correlated with salinity(P = 0.044,r = 0.823),while the abundance of nosZ gene was negatively correlated with salinity(P = 0.013,r = 0.905),and there was a significant positive correlation with TOC(P = 0.031,r = 0.852).The abundance of nirS and nosZ genes was affected by salinity,NO2-and TOC concentrations.The abundance of nirS and nosZ genes was affected by environmental factors.The results showed that the main environmental factors of nirK,nirS and nosZ genotype denitrifying bacteria were NH4+ and NO3-,Sal and NH4+,Sal and NO2-,respectively.There was no significant correlation between the number of nirK and the environmental factors,and nirS was significantly correlated with ORP,DO and NH4+(P <0.05),which indicated that the change of nirS was more obvious than that of nirK.While the diversity of nosZ was significantly correlated with pH,ORP and DO.The results showed that the dominant genus of Sinorhizobium was 23.55%,which was negatively correlated with the content of rhizobia and the concentration of NO3(P = 0.019,r =-0.885,P = 0.09,r =-0.921).It is presumed that the influencing factors of Rhizobium genus may be NO3-,and the relationship between Rhizobium and Rhizobium may be antagonistic(Pseudomonas),the proportion of nirS gene was 19.64%,which was significantly negatively correlated with the pathogen of rhizosphere(P = 0.000,r =-0.985),suggesting that Pseudomonas may have a mutually antagonistic relationship with slow rhizobia.The results showed that the dominant species of Azospirillum was 25.69%,but there was no significant correlation between the genus Rhizosphere and the secondary dominant species.The denitrification dominance of the nirK and nosZ genes belongs to the genus Rhizobium and Nitz virion,and all of them are aerobic azotobacteria and the nitrogen azotobacteria.The denitrification process is not yet clear.The dominant bacteria and other bacteria The relationship between the two is not clear,if the study of its reaction mechanism will be on the estuary of nitrogen removal has a huge contribution.In this study,the Liaohe estuary was used to study the spatial and temporal distribution of the abundance of functional microbial groups involved in the critical process of nitrogen cycle in estuaries.The response of microorganisms to environmental factors was used to reveal the nitrogen cycle The microbial driving mechanism of the key process,the research results will be the control of nitrogen removal,analysis of coastal ecosystem service function changes have important guiding significance. |
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