Response and synergistic effect of microbial community to submerged macrophyte in restoring urban black and smelly water bodies

The issue of black and smelly water bodies has been important for urban management, and ecological restoration by submerged macrophytes is an effective technology to prevent and control black and smelly water bodies. This study selected Vallisneria natans, Ceratophyllum demersum, and Potamogeton malainus to restore black and smelly water bodies. Based on the removal performance of chemical oxygen demand (COD), total phosphorus (TP), ammonia nitrogen (NH4+-N), and total nitrogen (TN), the influence of biological community was evaluated by different planting structure of submerged macrophytes and high-throughput DNA sequencing, so as to study the relationship of microorganism and submerged macrophyte. The experiment results showed that the removal efficiency of COD, TP, NH4+-N and TN of submerged macrophytes could reach 89.4 %, 92.7 %, 94.9 % and 92.8 %, respectively, and Vallisneria natans + Potamogeton malainus yielded the best results for water restoration. Sequencing showed that Proteobacteria, Actinobacteria, Bacteroidetes, and Cyanobacteria were the common dominant phyla, while microbial community composition at genus level varied among different planting patterns. Pearson correlation analysis revealed that Proteobacteri and Bacteroidetes positively correlated with the removal efficiency of pollutants. These results suggest that mixed submerged macrophytes improve water quality better than monotype, and affect the microbial diversity and composition.