Domesticating a Halotolerant Bacterium of Vibrio sp. LY1024 with Heterotrophic Nitrification–Aerobic Denitrification Property for Efficient Nitrogen Removal in Mariculture Wastewater Treatment

Dealing with mariculture wastewater that contains high nitrogenous compounds with efficient biological nitrogen removal technology is challenging but meaningful. The key lies in developing an active microorganism that can spontaneously complete the nitrification–denitrification processes in the marine environment. Herein, a halotolerant heterotrophic nitrification–aerobic denitrification (HN-AD) bacterium of Vibrio sp. LY1024 with good nitrogen removal capacity is domesticated to achieve the aforementioned goal. As a result, ammonium (NH₄⁺-N) and nitrate (NO₃⁻-N) removal rates of almost 100% and 98.5% are detected over Vibrio sp. LY1024 at the salinity of 3.5%, even further increasing the salinity of wastewater to 5.5%. Its removal capacity towards both NH₄⁺-N and NO₃⁻-N can still maintain at almost 100% and 94.7%, respectively. Further combining these results with those of intermediate product determination, it can be speculated that the ammonium removal is according to the pathway of NH₄⁺-N → NH₂OH → NO₃⁻-N → N₂O → N₂. Moreover, the influence of wastewater temperature on the nitrogen removal efficiency of Vibrio sp. LY1024 is also considered. The NH₄⁺-N and NO₃⁻-N removal efficiency over Vibrio sp. LY1024 at a relatively low temperature of 15 °C is still up to 97.3% and 76.4%, respectively. Our work provides a promising halotolerant and low-temperature resistance microorganism for the treatment of mariculture wastewater.