Nitrogen removal characteristics and salt tolerance mechanisms of the novel bacterium Halomonas sp. W07 in saline wastewater treatment

The extremely high osmotic pressure that frequently emerges in industrial wastewater will notably impact microorganisms' survival and nitrogen removal efficiency. A newly isolated Halomonas sp. strain W07 demonstrated the ability to efficiently remove nitrate and nitrite at an average rate of 4.68 and 5.56 mg/L/h, respectively, under an 8 % salinity condition. Whole-genome sequencing and nitrogen balance analysis revealed that W07 utilize the dissimilatory nitrate reduction to ammonium (DNRA) and ammonium assimilation pathways, including genes nap, nar, nasA, nir, glnA, gltBD, and gdhA2, to accomplish efficient nitrogen assimilation and removal in a high-salt environment. Furthermore, the expression of genes associated with salinity tolerance in W07 suggested that the strain can withstand osmotic stress by enhancing extracellular polymer secretion and facilitating the transport and synthesis of compatible solutes. The notable nitrogen removal efficiency and high salinity tolerance exhibited by strain W07 make it a promising candidate for nitrate removal under high-salt conditions.