Insight into the metabolic pathway of EAD based on metabolic flux, microbial community, and enzyme activity

Electrochemical anaerobic digestion (EAD) is essential for methane production. In this study, a cell net analyzer (CNA) was used to analyze the EAD metabolic flux and pathway and explore the dynamic changes in microbial community composition and critical enzyme activities by next-generation sequencing (NGS) and enzyme-linked immunosorbent assay (ELISA) to explore the reason for the high methane production rate of EAD. The results showed that EAD was more inclined toward hydrogen reduction of CO2 than conventional anaerobic digestion. Metabolic flux analysis (MFA) confirmed that the Embden-Meyerhof-Parnas (EMP) pathway was the main glycolysis pathway. According to metabolic flux analysis, hydrogen production from the electrodes accounted for 45.04%. Fermentimonas enhances the source of hydrogen, thereby facilitating the pathway of methane production by hydrogen reduction of CO2. Methanobacterium is the only dominant hydrotropic methanogen. Nicotinamide adenine dinucleotide (NAD) upregulates the hydrogen production pathway, whereas methylofuran (MFR) and tetrahydromethanopterin (MH4) are specific enzymes in the hydrogen-reducing CO2 pathway. Therefore, the results of this study help further reveal the electrochemical and biological principles related to EAD and provide theoretical support for the methanogenesis metabolism mechanism of EAD.

Automated summary

In this study, the metabolic flux and pathway of electrochemical anaerobic digestion (EAD) were investigated using a cell net analyzer (CNA). The results showed that EAD was more inclined towards hydrogen reduction of CO2 and the Embden-Meyerhof-Parnas (EMP) pathway was the main glycolysis pathway. The study also revealed the role of Fermentimonas in enhancing hydrogen production and the specific enzymes involved in the hydrogen-reducing CO2 pathway.