Enhancing the Startup Rate of Microbial Methanogenic Systems through the Synergy of β-lactam Antibiotics and Electrolytic Cells

Abstract

The slow startup and suboptimal efficiency of microbial carbon sequestration and methane-production systems have not been fully resolved despite their contribution to sustainable energy production and the reduction of greenhouse gas emissions. These systems often grapple with persistent hurdles, including interference from miscellaneous bacteria and the slow enrichment of methanogens. To address these issues, this paper examines the synergistic effect of coupling β-lactam antibiotics with an electrolytic cell on the methanogenic process. The results indicated that β-lactam antibiotics exhibited inhibitory effects on Campylobacteria and Alphaproteobacteria (two types of miscellaneous bacteria), reducing their relative abundance by 53.03% and 87.78%, respectively. Nevertheless, it also resulted in a decrease in hydrogenogens and hindered the CO₂ reduction pathway. When coupled with an electrolytic cell, sufficient electrons were supplied for CO₂ reduction to compensate for the hydrogen deficiency, effectively mitigating the side effects of antibiotics. Consequently, a substantial improvement in methane production was observed, reaching 0.57 mL·L^-1·d^-1, exemplifying a remarkable 6.3-fold increase over the control group. This discovery reinforces the efficiency of methanogen enrichment and enhances methane-production levels.

Keywords: PICRUSt2; inhibiting miscellaneous bacteria; microbial community; microbial methanogenic system; rapid start technology.

Figure 1

Schematic diagram of reactor unit.

Figure 2

Structure of methane-producing community: (a) Number of total OTUs for ABX.E.5, E.5, ABX.5, CG.5, and NaAc.5; (b) Species evolutionary tree at genus level.

Figure 3

Evolution of methane-producing communities: (a) Histogram of stacked relative abundance percentages of bacteria; (b) Histogram of stacked absolute abundance of archaea.

Figure 4

The methane-production rate under different experimental conditions: (a) Methane-production rate; (b) Gas chromatogram of experimental sample.

Figure 5

Biochemical pathways for methane production. (blue arrows: the acetate pathway; red arrows: the H₂/CO₂ pathway; green arrows: the pathways for the generation of Coenzyme M; yellow arrows: the pathways for the generation of Coenzyme B).

Figure 6

Abundance prediction of enzymes involved in biochemical pathways of methane production.

Figure 7

Illustration of methane-production process under different conditions.