Culture conditions of deep-sea fish-derived strain Alloalcanivorax xenomutans AXMZ1 and its removal efficiency of inorganic nitrogen and phosphorus

To investigate the removal efficiency of inorganic nitrogen and phosphorus from mariculture wastewater by the deep-sea fish-derived strain Alloalcanivorax xenomutans AXMZ1 under different culture conditions, we perfomed batch experiments at salinities of 5‰, 10‰, 25‰, and 40‰, pH levels of 4, 6, 8, and 10, and temperatures of 10, 20, 30, and 40 °C, and periodically measured pllutant concentrations. The results showed that strain AXMZ1 grew well across all tested ranges (Salinity 5‰–40‰, pH 4–10, temperature 10–40 °C), demonstrating broad environmental adaptability. The strain exhibited remarkable removal efficiencies for phosphate, nitrite nitrogen, and nitrate nitrogen. At 20°C, phosphate removal remained stable at 93.5%–96.5%, nitrite nitrogen removal exceeded 99.6%, nitrate nitrogen removal ranged from 95.8% to 97.3%, and total inorganic nitrogen removal reached 77.0%–87.4%. At salinity 40‰, nitrite and nitrate nitrogen removal rates reached 99.7% and 97.9%, respectively. At pH 10, the maximum total inorganic nitrogen removal of 98.1% was achieved. Although ammonia nitrogen removal was relatively lower (Maximum 69.0%), the strain's capacity for nitrite and nitrate nitrogen removal substantially surpassed that of most previously reported marine denitrifying bacteria. In conclusion, strain AXMZ1 combines high-efficiency nitrogen and phosphorus removal capabilities with excellent environmental adaptability, showing particular advantages under moderate-to-high salinity (25‰–40‰), slightly alkaline (pH 8–10), and low-temperature (20 °C), indicating promising potential for the bioremediation of mariculture wastewater and the restoration of marine nitrogen and phosphorus pollution.