Analysis Of Microbial Communities In Vertical-Flow Constructed Wetland-Recirculating Aquaculture System

The present study was conducted to evaluate the bacterial community composition and diversity of the water,rhizosphere and substrate of Pontedeira and Thalia dealbata in Vertical-flow Constructed Wetland-Recirculting Aquaculture System during operation in late summer and early autumn.All parameters were measured using PCR-DGGE and DNA sequencing technology.Results indicated that the types and quantity of the microorganisms among the rhizosphere and substrate of two plants and the water were different.Shannon-Wiener index of aquaculture pond water?inlet and outlet were 3.08?3.11?3.17,respectively;Shannon-Wiener index of Pontederia and Thalia dealbata were 3.61 and 3.47,respectively.It further explained that the root of Pontederia in the wetland can enrich the microorganisms around of the substrate better which increase the diversity of bacterial community.It was found that there were difference of microbial community structure through the similarity analysis of the rhizosphere microorganisms between two plants,and of the water microorganisms between quaculture pond water?inlet and outlet.The microorganisms of rhizosphere and substrate around of the Thalia dealbata has higher similarity(50%?68%?57%?67%,respectively),so the root of Pontederia are greatly influenced by the environment on the aggregation of microorganisms.Diversity of microbial community structure indicated that the microbial community of the three water zones in wetland-recirculting aquaculture system during the experimental period belong to 8 class:Proteobacteria(a-??-??-)?Bacteroidetes?Firmicutes?Deferribacteres?Verrucomicrobia?Cyanobacteria?Actinobacteria and Acidobacteria.The results of the present study indicated that Proteobacteria(28.4%)and Bacteroidetes(26.8%)were the main group of bacteria in the wetland-recirculting aquaculture system during the experimental period;Rhizosphere and substrate microbial community around of' the two plants belong to 7 class:Proteobacteria(a-??-??-??-)?Bacteroidetes?Chloroflexi?Acidobacteria?Firmicutes?Chlorobi and Verrucomicrobia.Proteobacteria(72%)was the main group of bacteria which was enriched by the two plants during the experimental period.This experiment provided some theoretical criterion for the structure of new Constructed Wetland-Recirculting Aquaculture System and the plants optimization of artificial wetland system in the future.