LAUSR

Abstract A novel halophilic bacterium capable of heterotrophic nitrification–aerobic denitrification was isolated from the polyethylene fiber of a recirculating aquaculture system and identified Vibrio parahaemolyticus HA2. In this study, the degradation rate of ammonia nitrogen, nitric nitrogen and nitrite nitrogen were 99.06%, 97.35% and 34.91% respectively, and the pH increases furtherly proved existing denitrification during the growth of strain HA2. Genome sequencing showed that the ammonia monooxygenase (AMO), periplasmic nitrate reductase (NAP), nitrite reductase (NIR), nitric oxide reductase (NOR), hydroxylamine oxidase (HAO) and nitrous oxide reductase (N2OR) of strain HA2 were associated with the progress of nitrification and denitrification. Utilization of nitrite and nitrate as well as existence of NAP gene further proved aerobic denitrification ability of strain HA2. The aim is indicating great potential of strain HA2 for future full-scale applications in aquaculture