High-throughput Sequencing Analysis Of Functional Genes Of Denitrification In Pearl River

With the rapid economic development in the Pearl River Delta,the nitrogen pollution in Pearl River is becoming severe day by day.The nitrogen cycling that convert ammonium to dinitrogen is contribute to the solvement of nitrogen pollution in this ecosystem.In the nitrogen cycling,the denitrification is the main and key steps,which is the final process to reduce nitrate and nitrite to N2 O or N2.in denitrification process,the nitrate or nitrite was catalyzed by nitrate reductase Nar,nitrite reductase Nir,nitric oxide reductase Nor,and nitrous oxide reductase Nos.In this paper,we studied the microbial community that take part in the denitrification in the Pearl River.Firstly,the diversities of bacterial and archaeal 16 S rRNA genes in Pearl River water of Guangzhou section were analyzed by using Illumina Miseq high-throughput sequencing.Secondly,the diversity and abuandance of denitrification microorganisms were studied by high-throughput sequencing of five denitrifying functional genes,which were nap A,bac-nir K,AOA-nir K,nir S and nos Z.Finally,the denitrification process is constructed on the metagenomic and metatranscriptomic analysis.The main results are as follows:1.The bacterial and archaeal 16 S rRNA gene diversity in Jiao Kou,Bai Xianke,Hai Xinsha,Sui Shi,and Nan Sha sites of the Pearl River are as follows: the major bacterial group is from Proteobacteria(34.78~69.60%)and Cyanbacteria(7.55~35.65%).The high abundance of Cyanbacteria in Jiao Kou,Hai Xinsha and Sui Shi indicating the eutrophication in these three points.The major archaea is consist of Ammonia-oxiding archaea(AOA)and some crenarchaeota.Most of AOA are from Group I.1b-Thaumarchaeota,and the restare from Group I.1a-associatied and Group I.1a-Thaumarchaeota.2.The diversity of denitrification genes in Jiao Kou,Bai Xianke,Hai Xinsha,Sui Shi,Nan Sha sites of Pearl River are as follows: based on the results of nap A,bac-nir K,nir S and nos Z high-thoughput sequencing,we found that almost all of the denitrification microorganismsare from the phylum of Proteobacteria,which consisted by the genera of Escherichia,Pseudomonas,Achromobacter and Dechloromonas.In the community of AOA-nir K,all of the AOA are from the Group I.1a-AOA and an independent cluster which was named as the Pearl River cluster.This cluster accounted for 42.33 ~75.49% of total community in the five water samples.3.Metagenomic and metatranscriptomic libraries were constructed on the water and sediment samples from Sui Shi site of Pearl River.According to the results of meta analysis,the abundance of nitrification gene is far less than denitrification genein metagenomes,while the expression of nitrification gene is much higher than denitrification gene in metatranscriptomes.These results showed that the denitrification had a great potential,but the nitrification was strong from the expression level.According to the results of vertical distributionin water and sediment samples,the expression of denitrification gene is much higher in the sediment sample.The metagenomic and metatranscriptomic analysis suggested the major microorganisms that participated in the nitification are Nitrosomona and Nitrospria,while the genera of Pseudomonas,Dechloromonas,Acidovorax and Streptomyces are main in denitrification...