1. Extracellular-proton-transfer driving high energy-conserving methanogenesis in anaerobic digestion.
- Author
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Liu, Haoyu, Xu, Ying, Li, Xinyu, Wang, Hong, Liu, Rui, and Dai, Xiaohu
- Subjects
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ANAEROBIC digestion , *SEWAGE sludge , *ADENOSINE triphosphate , *ENERGY conservation , *DRUGGED driving - Abstract
• Efficient extracellular proton transfer (EPT) was achieved in anaerobic digestion. • Efficient EPT promoted the participation of water in methane generation. • Efficient EPT facilitated the proton motive force generation and ATP synthesis. • A new principle of EPT propelling energy-conserving methanogenesis was proposed. Anaerobic digestion (AD) is a promising technology to realize the conversion from organic matters to methane, which is highly mediated by syntrophic microbial community via mutualistic interactions. However, small energy available in methanogenic conversion usually limits the metabolic activity. To adapt such energy-limited environment, efficient energy conservation is critical to support active physiological functions of anaerobic consortia for methanogenic metabolism. In this study, the contribution of extracellular proton transfer (EPT) enhancement to achieving energy-conserving methanogenesis in AD was explored. Proton-conductive medium (PCM) was applied to construct efficient proton transport pathway, and a large number of protons from extracellular water were found available to upregulate methanogenesis in AD, as indicated by the increase in the content of 2H (D) in methane molecules (over 40.7%), among which CO 2 -reduction-to-CH 4 was effectively enhanced. The increases of adenosine triphosphate (ATP) concentration (+54.1%) and gene expression activities related to ATPase (+100.0%) and proton pump (+580.1%) revealed that enhanced EPT by PCM promoted transmembrane proton motive force generation to facilitate ATP synthesis. Based on genome-centric metatranscriptomic analyses, MAG14, MAG63 and MAG61 with high energy conservation activity displayed most pronounced positive response to the EPT enhancement. In these core MAGs, the metabolic pathway reconstruction and the key genes activity identification further proved that EPT enhancement-driven efficient ATP synthesis stimulated the cross-feeding of carbon and proton/electron to facilitate microbial mutualism, thereby resulting in the high energy-conserving methanogenesis. Overall, our work provides new insights into how EPT enhancement drives high energy-conserving methanogenesis, expanding our understanding of the ecological role of EPT in AD. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2024
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