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Updated: Jan 14, 2026

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Sequential oxygen intervention drives novel AOB-DGAOs interaction network enabling advanced nitrogen removal in
Li Zhang1, Yiqing Zhang1, Yu-You Li2
1National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing, China.
None:
The simultaneous partial nitrification and endogenous denitrification (SPNED) process, driven by ammonia-oxidizing bacteria (AOB) and denitrifying glycogen-accumulating organisms (DGAOs), shows significant potential for low-carbon wastewater treatment. However, rapid startup and efficiency are challenged by persistent nitrite-oxidizing bacteria (NOB) proliferation under low NH4+-N conditions and dissolved oxygen depletion of intracellular polyhydroxyalkanoates (PHA) in DGAOs. Here, a sequential oxygen intervention strategy is innovatively proposed: DGAOs population dominance was first established through anaerobic/anoxic mode, followed by a mid-position aerobic phase to construct a DGAOs-dominated AOB-DGAOs interaction network. SPNED startup was achieved within 46 days with > 99 % nitrogen removal efficiency. Co-occurrence networks and metagenomics revealed functional bacterial cooperation enabling carbon-efficient nitrogen removal. Results demonstrated that enriched DGAOs (abundance increased from 9.22 % to 28.25 %) preferentially consumed NO2--N over oxygen under microaerobic conditions, starving NOB and creating a low-competition niche for AOB. Consequently, AOB abundance surged 22.69-fold within 16 days. Correspondingly, AOB-generated low-electron-demand NO2--N reduced endogenous electron (NADH from PHA degradation) requirements for DGAOs denitrification. Furthermore, Candidatus Contendobacter (NO2--N → NO) and Candidatus Competibacter (NO → N2) within DGAOs potentially executed stepwise denitrification, avoiding NADH loss through intra-community substrate competition. Coupled with subsequent oxygen intervention, activation of β-oxidation (151.4 % up-regulation in key enzyme) and TCA cycle (96.0 % increase in α-ketoglutarate dehydrogenase) in DGAOs boosted intracellular NADH levels 1.76-fold. This NADH-rich environment enhanced DGAOs functionality and sustained enrichment, stabilizing the AOB-DGAOs network for advanced nitrogen removal. This study proposes a previously underappreciated NOB-inhibition function of DGAOs, offering a novel strategy for efficient endogenous carbon utilization, advanced nitrogen removal, and operational stability.
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