[The relationship between methane production metabolic flux and microorganisms in a microbial electrolytic cell coupled anaerobic digestion].

In this study, voltage was used as a disturbance factor to investigate the relationship between microbial community and methane (CH ₄ ) production flux in a microbial electrolytic cell coupled anaerobic digestion (MEC-AD). Metabolic flux analysis (MFA) was used to explore the relationship between the CH ₄ metabolic flux produced and the microbes. The results showed that both methane production flux and hydrogen production flux changed significantly upon voltage disturbance, while the voltage disturbance had little effect on acetic acid production flux. The maximum CH ₄ production flux under 0.6 V disturbance was 0.522±0.051, which increased by 77% and 32%, respectively, compared with that of the control group under 1.0 V (0.295±0.013) and under 1.4 V (0.395±0.029). In addition, an average of 15.7%±2.9% of H ₂ (flux) was used to reduce CO ₂ to produce CH ₄ and acetic acid, and an average of 27.7%±6.9% of acetic acid (flux) was converted to CH ₄ . Moreover, the abundance of Lachnospiraceae significantly affected the flux of acetic acid. The flux of CH ₄ production is positively correlated with the abundances of Petrimonas , Syntrophomonas , Blvii 28, and Acinetobacter , and negatively correlated with the abundances of Tuzzerella and Sphaerochaeta . The species that affected the flux of H ₂ and CH ₄ were similar, mostly belonging to Bacteroides , Clostridium , Pseudomonas and Firmicutes . Furthermore, the interspecies interaction is also an important factor affecting the MEC-AD methanogenesis flux.