Unveiling the impact of temperature shift on microbial community dynamics and metabolic pathways in anaerobic digestion

Abstract

Anaerobic digestion (AD) technology is a viable solution to the challenges attributed to sewage sludge, but its specific impact on biogas production and the dynamics of methanogenic bacteria has not been widely understood. This research investigated the effects of shifts in AD operational temperatures on microbial communities and biogas production. This was achieved by incrementally raising the temperature from 37 °C to 45 °C in 2 °C increments. Within the temperature range of 37 – 41 °C, there was a notable disturbance in the abundance of acetogenic bacteria and methanogens, leading to a considerable reduction in methane production. However, with further elevation of temperature, the increasing activity of acetogens and methanogens was discerned following the increase in methane production. Methanothrix was identified as the predominant methanogen in the present study, marking the domination of the acetoclastic pathway. In functional analysis, the acetate decarboxylation enzymes demonstrated resilience at 43 °C and 45 °C, in contrast to hydrogenotrophic pathway enzymes. The acetoclastic pathway played a primary role in methane production under temperature shift conditions while the hydrogenotrophic pathway was more susceptible to temperature fluctuations. The findings highlight the potential adaptation of microbial communities when subjected to changing temperatures which led to robustness of digestion in AD processes.