Effect of Reclaimed Water on Bacterial Community Composition and Function in Urban River Sediment

Abstract

In order to study the effect of reclaimed water on bacterial community composition and function in urban river sediment, the changes of bacteria community diversity, composition and function in Mayu wetland upon the supply of reclaimed water were investigated by a range of sophisticated procedures, including Terminal Restriction Fragment Length Polymorphism(T-RFLP), 16S rRNA clone library technology, and Real-time Quantitative PCR Detecting System(qPCR).The results showed that carbon, nitrogen and phosphorus were major factors driving the variation of bacterial diversity and community structure in river sediment, and the bacteria were gradually recovered after purification in downstream under the effect of artificial wetland. In addition, the bacterial community in reclaimed water outfall was mainly constituted by β-Proteobacteria, δ-Proteobacteria, Bacteroidales and Cyanobacteriain, and ε-Proteobacteria, Chloroflexi and Spirochaetes were unique groups. Besides, the major biological geochemical cycle was nitrogen, carbon and phosphorus cycle in river sediment, which was closely related to functional genes. There were about 45.9% of the clones related to nitrogen cycle in reclaimed water outfall, such as Comamonas sp., higher than those of upstream and downstream (27.7% and 23.4%), 17.9% of the clones were closely related to the carbon cycle, such as Lysobacter sp., higher than those of upstream and downstream (14.4% and 12.9%). Furthermore, the trace of pathogenic bacteria and antibiotics in reclaimed water also changed the transformation pattern participating in carbon and nitrogen cycle, for example, Rhodocyclus sp. conducted nitrogen fixation by photosynthesis in reclaimed water outfall, whereas Burkholderia sp. fixes nitrogen by ways of plants symbiotic nitrogen fixation in upstream and downstream. This research provides theoretical reference for studies on remediation of reclaimed water supplying river by artificial wetland.