Characteristics of Bacterial Communities in Cyanobacteria-Blooming Aquaculture Wastewater Influenced by the Phytoremediation with Water Hyacinth

Cyanobacterial blooms often occur in aquaculture wastewater in China. A floating plant, water hyacinth has been widely used to treat this wastewater. Little is known, however, about bacterial community characteristics and the risk of potential pathogens in cyanobacteria-blooming aquaculture wastewater remediated by water hyacinth. In wastewater treated with water hyacinth, we used culture enumeration and high-throughput sequencing to explore the characteristics of bacterial communities, the status of coliform bacteria, and pathogenic bacteria potentially conducive to human disease. Our results indicated that the relative abundance of Acidobacteria, Planctomycetes, Actinobacteria, Chlorobi, Cyanobacteria, Proteobacteria, and phylum OD1 in cyanobacteria-blooming aquaculture wastewater were significantly influenced by water hyacinth. After 30 days, the relative abundance of Proteobacteria and phylum OD1 in the water hyacinth treatments increased remarkably, while the relative abundance of the other 5 phyla in treatment was significantly reduced compared with the controls. In 21 major families, the relative abundance of Comamonadaceae, Oxalobacteraceae, Rhodocylclaceae, and an unnamed group from phylum OD1 increased significantly in the water hyacinth treatments compared with the controls. The number of total coliforms in wastewater treated by water hyacinth was significantly elevated and higher than controls during the first 6–18 days, with the maximum reaching 23,800 MPN/L. The level of potential pathogenic bacteria in wastewater treated by water hyacinth significantly reduced compared with the controls after 18 days, but it significantly increased from the initial level. It appears that water hyacinth by itself is not an effective treatment for reducing potential pathogens in aquaculture water.