首页|Fulvic acid mediated highly efficient heterotrophic nitrification-aerobic denitrification by Paracoccus denitrificans XW11 with reduced C/N ratio

Fulvic acid mediated highly efficient heterotrophic nitrification-aerobic denitrification by Paracoccus denitrificans XW11 with reduced C/N ratio

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  • Elsevier
© 2024 Elsevier LtdReducing the C/N ratio requirements for heterotrophic nitrification-aerobic denitrification (HNAD) is crucial for its practical application; however, it remains underexplored. In this study, a highly efficient HNAD bacterium, Paracoccus denitrificans XW11, was isolated. The HNAD characteristics of XW11 were studied, and the redox mediator fulvic acid (FA) was used to reduce the C/N requirements. Whole-genome sequencing revealed multiple denitrification genes in XW11; however, nitrification genes were not identified, because heterotrophic nitrification-related gene sequences were not included in the database. However, the nitrogen removal related enzyme activity test revealed complete nitrification and denitrification pathways. Reverse transcription PCR showed that the membrane-bound nitrate reductase (NarG), rather than the periplasmic nitrate reductase, was responsible for aerobic denitrification. The conventional nitrite reductase (NirS) also does not mediate nitrite denitrification. When the C/N ratio was 10, the ammonia removal efficiency of the Control was 71.71 % and the addition of FA increased it to 86.12 %. Transcriptomic analysis indicated electron flow from the carbon source to FA without proton transmembrane transport, and the presence of FA constructs another electron transfer system. The redox potential of oxidized FA/reduced FA is 0.3679 V, avoiding competition for electrons from Complex III. Thus, ammonia monooxygenase obtains electrons more easily, thereby promoting nitrification. The enzyme activity test of the nitrification process confirmed this view. In addition, NarG expression increased, and the denitrification process was enhanced. Overall, FA improved HNAD efficiency by facilitating electron transfer to the nitrogen dissimilation process, offering a novel approach to reduce the C/N requirement of HNAD.

Electron transport chainFulvic acidHeterotrophic nitrification-aerobic denitrificationParacoccus denitrificansRedox mediator

Wu Y.、Cui Y.、Li D.、Yin M.、Pei Y.、Li J.、Zhu Y.、Wang X.

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National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology Beijing University of Technology

National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology Beijing University of Technology||Beijing University of Technology

The College of environmental and chemical engineering Jiangsu University of Science and Technology

2024

10.1016/j.watres.2024.122557

Water research: A journal of the international water association

Water research: A journal of the international water association

EI
ISSN：0043-1354
年,卷(期)：2024.267(Dec.1)
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