Bioaugmentation of woodchip bioreactors by Pseudomonas nicosulfuronedens D1-1 with functional species enrichment

A novel heterotrophic nitrification and aerobic denitrification (HN-AD) bacterium D1-1 was identified as Pseudomonas nicosulfuronedens D1-1. Strain D1-1 removed 97.24%, 97.25%, and 77.12% of 100 mg/L NH4+-N, NO3--N, and NO2--N, with corresponding maximum removal rates of 7.42, 8.69, and 7.15 mg·L-1·h-1, respectively. Strain D1-1 bioaugmentation enhanced woodchip bioreactor performance with an average NO3--N removal efficiency of 93.8%. Bioaugmentation enriched N cyclers along with increased bacterial diversity and predicted genes for denitrification, DNRA (dissimilatory nitrate reduction to ammonium), and ammonium oxidation. It also reduced local selection and network modularity from 4.336 to 0.934, resulting in predicted nitrogen (N) cycling genes shared by more modules. These observations suggested that bioaugmentation could enhance the functional redundancy to stabilize the NO3--N removal performance. This study provides insights into the potential applications of HN-AD bacteria in bioremediation or other environmental engineering fields, relying on their ability to shape bacterial communities.