How β‑Cyclodextrin-Functionalized Biochar Enhanced Biodenitrification in Low C/N Conditions via Regulating Substrate Metabolism and Electron Utilization

• Published in: Environmental science & technology 2023-08, Vol.57 (30), p.11122-11133
• Main Authors: Shi, Hongtao, Feng, Xiaochi, Xiao, Zijie, Jiang, Chenyi, Wang, Wenqian, Zhang, Xin, Xu, Yujie, Wang, Caipeng, Guo, Wanqian, Ren, Nanqi
• Format: Article
• Language: English
• Subjects: Accumulation; beta-Cyclodextrins; Bioremediation; Bioremediation and Biotechnology; Carbon/nitrogen ratio; Charcoal; Cyclodextrins; Denitrification; Electron transfer; Electrons; Emission analysis; Enzymatic activity; Glucose; Glucose metabolism; Glycolysis; Intermediates; Metabolism; Metabolites; Nitrate reduction; Nitrates - metabolism; Nitrogen; Nitrogen - metabolism; Nitrous oxide; Oxidative phosphorylation; Pentose; Pentose phosphate pathway; Phosphorylation; Positive feedback; Substrates; Transcriptomics; Tricarboxylic acid cycle; Utilization; Wastewater; Water pollution; β-Cyclodextrin
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.3c02482

Biodenitrification plays a vital role in the remediation of nitrogen-contaminated water. However, influent with a low C/N ratio limits the efficiency of denitrification and causes the accumulation/emission of noxious intermediates. In this study, β-cyclodextrin-functionalized biochar (BC@β-CD) was synthesized and applied to promote the denitrification performance of Paracoccus denitrificans when the C/N was only 4, accompanied by increased nitrate reduction efficiency and lower nitrite accumulation and nitrous oxide emission. Transcriptomic and enzymatic activity analyses showed BC@β-CD enhanced glucose degradation by promoting the activities of glycolysis (EMP), the pentose phosphate pathway (PPP), and the tricarboxylic acid (TCA) cycle. Notably, BC@β-CD drove a great generation of electron donors by stimulating the TCA cycle, causing a greater supply of substrate metabolism to denitrification. Meanwhile, the promotional effect of BC@β-CD on oxidative phosphorylation accelerates electron transfer and ATP synthesis. Moreover, the presence of BC@β-CD increased the intracellular iron level, causing further improved electron utilization in denitrification. BC@β-CD helped to remove metabolites and induced positive feedback on the metabolism of P. denitrificans. Collectively, these effects elevated the glucose utilization for supporting denitrification from 36.37% to 51.19%. This study reveals the great potential of BC@β-CD for enhancing denitrification under low C/N conditions and illustrates a potential application approach for β-CD in wastewater bioremediation.