Heterotrophic nitrifying and aerobic denitrifying bacteria: Characterization and comparison of shrimp pond and effluent discharge channel in aspects of composition and function

The rapidly growing aquaculture industry is associated with numerous environmental problems, especially nitrogen pollution. The HNAD (heterotrophic nitrifying/aerobic denitrifying) bacteria emerging as efficient nitrogen removal life forms were characterized and compared in shrimp pond and effluent discharge channel from the aspects of composition and function. Eighty three HNAD bacterial strains belonging to the Proteobacteria, Firmicutes, Actinobacteria and Deinococcus-Thermus were found. Alpha diversity index by Shannon and Chao1 showed more diverse genera in effluent channel than shrimp pond water. The mean potential nitrate-N removal activity was significantly higher in effluent channel water (15.57 ± 3.39) as compared to shrimp pond (9.06 ± 5.76). Nitrate reduction, nitrate respiration and aerobic chemoheterotophy were significantly higher in effluent channel than shrimp pond. This study will help in understanding and developing culturable HNAD bacteria for successful transformation of nitrogenous waste in coastal aquaculture and wastewater treatment systems. •Eighty three HNAD bacterial strains (44 from Shrimp ponds and 39 from effluent channels) were isolated and identified.•The most dominant phyla were found to be Proteobacteria, Firmicutes, Actinobacteria and Deinococcus-Thermus.•Diversity indices revealed the presence of diverse genera in effluent channel in comparison to shrimp pond water.•Azoarcus and Acinetobacter acted as a keystone species in effluent channel and shrimp pond, respectively.•Nitrate respiration and aerobic chemoheterotophy were significantly higher in effluent channel than shrimp pond.