Bioactive Sulfide\nStimulates Sulfur-Oxidizing and\nDenitrifying Bacteria to Accelerate Nitrogen Removal: A Novel Biological\nApproach to Water Purification

Nitrogen pollution causes eutrophication\nand algal blooms\nworldwide.\nAlgae-derived organic sulfides can interact with organisms to affect\nnitrogen cycling, but the associated patterns and mechanisms remain\nunclear. This study investigated the effects of dimethylsulfoniopropionate\n(DMSP), an important bioactive sulfide, on nitrogen transformation\nand removal at the water–sediment interface in microcosm systems\n(water–sediment and water–sediment–biofilm–benthos).\nResults showed that DMSP altered the dynamics of total nitrogen and\ndissolved inorganic nitrogen in overlying water, particularly promoting\n74.39% reduction of nitrate in the system containing biofilm and benthos.\nThe presence of DMSP in conjunction with biofilm and bioturbation\naffected the nitrogen transformation in the sediment. DMSP increased\nthe content of dissolved organic carbon but decreased the content\nof dissolved oxygen in water. Moreover, it was converted to sulfate\nin water, enhancing the abundance of bacteria capable of denitrification\nand sulfur oxidation (such as <i>Pseudomonas</i>) as well\nas related genes, including <i>narGHI</i>, <i>norBC</i>, <i>soxA</i>, <i>soxC</i>, <i>soxY</i>, and <i>soxZ</i>, in the biofilm. This observation suggests\nthat the process of sulfur oxidation promotes denitrification. The\ncurrent study highlights the potential applications of DMSP in water\npurification systems and presents a novel biological approach to aquatic\nmanagement.