Heterotrophic nitrification and aerobic denitrification by Pseudomonas sp. HE-16: performance and mechanism for...

To obtain efficient microbial resources for Simultaneous Nitrogen and Phosphorus Removal (SNPR), Pseudomonas sp. HE-16 was isolated and screened from the aerobic tank of the Yingkou Sewage Treatment Plant in China. This study, for the first time, systematically investigated its aerobic nitrogen (N) and phosphorus (P) removal performance, metabolic pathways, and genomic characteristics. The results showed that strain HE-16 possesses strong heterotrophic nitrification, aerobic denitrification, and aerobic phosphorus removal abilities, achieving high removal efficiencies for NH₄^⁺-N, NO₃^⁻-N, NO₂^⁻-N, and PO₄^3⁻-P. Environmental factors-including carbon source, C/N, P/N, pH, temperature, shaking speed, and inoculation volume-were optimized using Plackett-Burman design, steepest ascent experiments, and response surface methodology (RSM), through which the optimal conditions were identified. Optimal conditions is C/N 7, pH 7, 34.15 ℃, shaking speed 140.27 r/min. Under optimal conditions, the removal efficiencies of NH₄⁺-N and PO₄^3⁻-P reached 56.24 ± 1.37 and 77.18 ± 0.65%, respectively, within 6 h. Whole-genome sequencing combined with functional gene annotation elucidated the molecular mechanisms underlying N and P removal. Strain HE-16 demonstrates strong potential for practical applications under low C/N conditions relative to conventional HN-AD strains (C/N 7-9), which is lower than most reported HN-AD strains.