Insights into the Acceleration Mechanism of Intracellular N and Fe Co-doped Carbon Dots on Anaerobic Denitrification Using Proteomics and Metabolomics Techniques

Abstract

Bulk carbon-based materials can enhance anaerobic biodenitrification when they are present in extracellular matrices. However, little information is available on the effect of nitrogen and iron co-doped carbon dots (N, Fe-CDs) with sizes below 10 nm on this process. This work demonstrated that Fe−N X formed in N, Fe-CDs and their low surface potentials facilitated electron transfer. N, Fe-CDs exhibited good biocompatibility and were effectively absorbed by Pseudomonas stutzeri ATCC 17588. Intracellular N, Fe-CDs played a dominant role in enhancing anaerobic denitrification. During this process, the nitrate removal rate was significantly increased by 40.60% at 11 h with little nitrite and N 2 O accumulation, which was attributed to the enhanced activities of the electron transport system and various denitrifying reductases. Based on proteomics and metabolomic analysis, N, Fe-CDs effectively regulated carbon/nitrogen/sulfur metabolism to induce more electron generation, less nitrite/N 2 O accumulation, and higher levels of nitrogen removal. This work reveals the mechanism by which N, Fe-CDs enhance anaerobic denitrification and broaden their potential application in nitrogen removal.

Effects of Weak Electric Fields on the Denitrification Performance of Pseudomonas stutzeri: Insights into Enzymes and Metabolic Pathways

“…The composition of the headspace gas in the reactor was determined using a gas chromatograph (GC3900, Rui-neng, Dongying, Shandong, China) equipped with a thermal Catholyte was prepared according to Tables S1 and S2. P. stutzeri (CCTCC AB 94052 or ATCC 17588), capable of denitrification under anaerobic conditions [19], was obtained from the China Center for Type Culture Collection (Wuhan, China) for cathode inoculation. The reactors and culture media underwent sterilization, and the catholyte underwent a 30 min aeration with high-purity N 2 to remove oxygen.…”

“…However, in pure culture systems, the mechanisms can be more clearly explored [ 16 , 17 ]. In this study, P. stutzeri , prominently featured in a previous biocathode system [ 18 ] and capable of complete denitrification under anaerobic conditions [ 19 ], was selected. The efficacy of P. stutzeri in treating low COD/N artificial wastewater under weak electric fields (constant voltage of 0.2, 0.4, and 0.6 V) was assessed in this study.…”