Macrophytes not only directly absorb nitrogen (N) from wastewater, but also influence N removal processes. They were achieved by microorganisms in rhizosphere through root exudations and oxygen secretion. However, changes of root exudes and rhizosphere microbial community structure in macrophytes in high N wastewater are still unclear. Objectives of this study were to investigate effects of dissolved organic carbon (DOC) and organic acids (OA) on composition and diversity of microbial communities across three macrophytes during treating swine wastewater. Result showed that secretion rates of DOC and total organic acid (TOA) displayed an increasing trend with extended experimental times in Pontederia cordata and Iris pseudacorus rhizosphere, while it presented a decline trend in Canna indica rhizosphere. Preponderant phyla in rhizosphere were Proteobacteria, Bacteroidetes, Firmicutes and Acidobacteria. Genera Geobacter enriched in I. pseudacorus rhizosphere, while unidentified_Cyanobacteria enriched in P. cordata rhizosphere. Diversity and richness of microbial communities in C. indica and P. cordata rhizosphere at different experimental periods showed no significant differences (P>0.05). However, diversity of microbial community increased in I. pseudacorus rhizosphere. Although interactions among microorganisms reduced, they became more mutualistic after treating swine wastewater. Concentration of NH4+-N and total nitrogen (TN), pH, dissolved oxygen (DO) in swine wastewater, malonic acid and succinic acid released by roots enhanced N cycle functions of microbial community. The results contribute to further comprehension of the mechanism of N removal in rhizosphere during treating swine wastewater.
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