Nitrogen removal by two strains of aerobic denitrification actinomycetes: Denitrification capacity, carbon source metabolic ability, and raw water treatment

•Actinomycetes strains M5 and M6 were identified as Streptomyces sp.•The TOC and NO3–-N removal efficiency of strains was higher than 97.02% and 95.44%.•Strains M5 and M6 had higher utilization performance for esters, amino acids.•Network model exhibited interaction of metabolic activity and fingerprinting.•The TN removal efficiency in raw water was ranged from 68.63% to 85.59%. The denitrification characteristics of actinomyetes in aquatic ecosystem under aerobic conditions are not well known. Here, two actinomyetes strains M5 and M6 were separated and annotated as Streptomyces sp. Strains M5 and M6 could reduce 95.02% and 96.84 % of total nitrogen, 98.14 % and 97.02 % of total organic carbon under aerobic condition. Nitrogen balance analysis indicated that 78.60 % and 83.01 % of nitrogen was translated into gaseous, with 13.48 % and 10.77 % of nitrogen was assimilated into biomass for strains M5 and M6. The highest removal efficiency of nitrate of strains M5 and M6 in micro-polluted water bodies were 88.61 % and 82.53 %, respectively. Moreover, strains M5 and M6 exhibited remarkable carbon metabolic capacity, especially for esters. Altogether, this study provides a new perspective for understanding the performance of actinomyetes in aerobic denitrification and micro-polluted water reparation.