Characteristics Of Bacteria And Denitrifying Bacteria Communities In Surface-flow Constructed Wetlands

Wetlands bacteria take part in the decomposition and transformation of nitrogen in the surface-flow constructed wetland ecosystem and denitrifying bacteria also function in denitrification.Denitrification is an important part of the nitrogen cycle and the key step to removal of nitrogen in surface-flow constructed wetlands.In this study,we explored space-time analysis with high-throughput sequencing to elucidate the relationships between bacteria community structures and water environmental factors and the relationships between denitrifying bacteria community structures and water environmental factors during different seasons.Our results showed that:(1)The bacterial abundance index(ACE)in May,August,and October were 2421.9,4022.2,and3737.3 respectively,whereas the Shannon-Weiner indexes were 6.027,6.691,and 6.601 respectively.Along the flow direction,the bacterial abundance initially decreased subsequently during the same months,although diversity tended to decrease.The abundance showed similar changes during the different months.Surface-flow constructed wetlands mainly contained 9 bacteria phyla and 22 bacteria genus(more than 1%).During different seasons,the same species processing units showed alternating changes,and during the same season,bacterial community structures were influenced by the frist genus proportion in different processing units.(2)The denitrifying bacterial abundance index(ACE)in May,August,and October were 686.8,996.2,and 996.2 respectively,whereas the Shannon-Weiner indexes were 3.718,4.303,and 4.432 respectively.Along the flow direction,the denitrifying bacterial abundance initially increased and then decreased subsequently during the same months,although diversity tended to increase.The abundance showed similar changes during the different months.Surface flow constructed wetlands mainly contained the following denitrifying bacteria genus: unclassified Bacteria(37.12%),unclassified Proteobacteria(18.16%),Dechloromonas(16.21%),unranked environmental samples(12.51%),unclassified Betaproteobacteria(9.73%),unclassified Rhodocyclaceae(2.14%)and Rhodanobacter(1.51%).During different seasons,the same species processing units showed alternating changes,and during the same season,bacterial community structures were influenced by the second genus proportion in different processing units.(3)The bacterial ACE was strongly correlated with electrical conductivity,dissolved oxygen and oxidation reduction potential.The bacterial diversity was strongly correlated with electrical conductivity,dissolved oxygen.The denitrifying bacterial ACE was strongly correlated with temperature,dissolved oxygen,and p H.The denitrifying bacterial diversity was strongly correlated with temperature,electrical conductivity,p H,and oxidation reduction potential.All denitrifying bacterial species were greatly affected by environmental factors,including temperature and p H,and the effects of electrical conductivity and oxidation reduction potential were similar.