Characteristics of a heavy metal resistant heterotrophic nitrification–aerobic denitrification bacterium isolated from municipal activated sludge

• Published in: Environmental research 2024-12, Vol.263 (Pt 2), p.120111, Article 120111
• Main Authors: Liu, Zhuang, Liu, Shixi, Ye, Yuanyao, Tang, Qian, Tian, Weimin, Liu, Huan, Li, Daosheng, Jiang, Wei, Wang, Zijie, Liu, Dongqi
• Format: Article
• Language: English
• Subjects: Aerobiosis; Cupriavidus - genetics; Cupriavidus - metabolism; Cupriavidus metallidurans TX6; Denitrification; Heavy metal resistance; Heterotrophic nitrification aerobic denitrification; Heterotrophic Processes; Metabolic pathway; Metals, Heavy - metabolism; Nitrification; Nitrogen - metabolism; Nitrogen removal; Sewage - microbiology
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2024.120111

The heterotrophic nitrification-aerobic denitrification (HNAD) is a new biological denitrification technology, the present study isolated a new HNAD strain named Cupriavidus metallidurans TX6 with heavy metal resistance. The gene expression, electron transport, enzyme activity and nitrogen removal property of strain TX6 were studied with different influencing factors. Strain TX6 has five nitrogen metabolism pathways (NH4+ → NH2OH → NO → NO2− → NH4+ → GOGAT/GDH; NH4+-N → NH2OH → NO → N2O → N2; NH4+ → NH2OH → NO → NO2− → NO3−; NO3− → NO2− → NH4+ → GOGAT/GDH; NO3−→ NO2− → NH4+ → GOGAT/GDH). Nitrogen balance analysis shows that 29 ± 4 mg/L of N was converted to intracellular nitrogen by assimilation and 50 ± 3 mg/L N loss may be attributed to aerobic denitrification. The results provide a theoretical basis for the HAND bacteria application in nitrogen removal from wastewaters containing heavy metals. [Display omitted] •New strain with heterotrophic nitrification-aerobic denitrification & Cu resistance.•Excellent nitrogen removal by Cupriavidus metallidu-rans sp. TX6 was studied.•Impacts of various factors on N removal by strain TX6 were explored and optimized.•Multiple N metabolic pathways were analyzed with new nitrifying enzymes predicted.