Phosphorus removal from eel aquaculture tailwater using bacterial strain EAT-5: Genomic analysis and removal mechanism

The challenges in eel aquaculture tailwater treatment in eel aquaculture have significantly affected the sustainable development of the eel aquaculture industry. This tailwater is characterized by high discharge volumes over short periods and low hydraulic retention time. In the water, residual feed has been detected in dissolved and particulate forms, with dissolved phosphorus being difficult to manage. In this study, the EAT-5 strain was isolated from aquaculture tailwater using a selective medium containing KH₂PO₄ as the sole phosphorus source, acclimatized to enhance phosphorus removal capacity, and classified by phylogenetic analysis. The findings confirmed the clustering of the strain EAT-5 clusters within the genus Olivibacter sp. Nov, which harbors the ppk1 , ppk2 , and ppx genes that encode polyphosphate kinase and exopolyphosphatase, along with genes involved in nitrogen metabolism, including those encoding periplasmic nitrate and nitrite reductases. These genetic characteristics enable the strain to remove nitrogen and phosphorus effectively. The optimal growth conditions for EAT-5 were glucose as the carbon source, a pH of 8, a temperature of 30 ℃, and a rotation speed of 120 rpm. The strain EAT-5 exhibited high phosphorus removal efficiency (64.3–88.3%) in practical eel aquaculture wastewater treatment. Thus, EAT-5 offers a promising and efficient approach for nutrient removal from eel aquaculture tailwater.