期刊
WATER RESEARCH
卷 189, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2020.116612
关键词
Intracellular electron transfer (IET); Extracellular electron transfer (EET); Bio-Pd(0); Aerobic denitrifiaction; Promotion mechanism
资金
- National Natural Science Foundation of China [41977316, 21677052]
- Guangdong technological innovation strategy of special funds [2018B020205003]
This study investigated the mechanisms of nanoparticles in aerobic denitrification for the first time, revealing that bio-Pd(0) can promote the removal of both nitrate and nitrite by accelerating electron transfer rate and improving affinity. It also provided insights into the electron transfer mechanisms in Gram-positive bacteria.
The slow electron transfer rate is the bottleneck to the biological wastewater treatment process, and the nanoparticles (NPs) has been verified as a feasible strategy to improve the biological degradation efficiency by accelerating the electron transfer. Here, we employed the Gram-positive Bacillus megaterium Y-4, capable of synthetizing Pd(0), to investigate the intra/extracellular electron transfer (IET/EET) mechanisms mediated by NPs in aerobic denitrification for the first time. Kinetic and thermodynamic results showed that the bio-Pd(0) could significantly promote the removal of both nitrate and nitrite by improving affinity and decreasing activation energy. The enzymic activity and the respiration chain inhibition experiment indicated that the bio-Pd(0) could facilitate the nitrate biotic reduction by improving the Fe-S center activity and serving as parallel H carriers to replace coenzyme Q to selectively increase the electron flux toward nitrate in IET, while promoting the nitrite reduction by abiotic catalysis. Most importantly, the detection of DPV peak at -226 similar to-287 mV proved that the one-electron EET via multiheme cytochrome-bound flavins also occurred in Gram-positive bacteria and enhanced in Pd-loaded cells. In addition, the remarkable increase of the formal charge in EPS indicated that the bio-Pd(0) could act as an electron shuttle to increase the redox site in EPS, eventually accelerating the electron hopping in long-distance electron transfer. Overall, this study expanded our understanding of the roles of bio-Pd(0) on the aerobic denitrification process and provided an insight into the IET/EET of Gram-positive strains. (C) 2020 Elsevier Ltd. All rights reserved.
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