Regulation of the autochthonous microbial community in excess sludge for the bioconversion of carbon dioxide to acetate without exogenic hydrogen

Abstract

The autochthonous microbial community from excess sludge was regulated for enhanced conversion of CO₂ to acetate without exogenic H₂. It was interesting that the acetate-fed system exhibited a surprising performance to regulate the microbial community for a high acetate yield and selectivity. As a result, some hydrogen-producing bacteria (e.g., Proteiniborus) and acetogenic bacteria with the ability of CO₂ reduction were enriched by acetate feeding, 2-bromoethanesulfonate (BES) addition and CO₂ stress. When the selected microbial community was applied to convert CO₂, the accumulation of acetate was positively correlated to the concentration of yeast extract. Finally, the acetate yield reached up to 67.24 mM with a high product selectivity of 84 % in the presence of yeast extract (2 g/L) and sufficient CO₂ in semi-continuous culture for 10 days. This work should help get new insights into the regulation of microbial community for the efficient acetate production from CO₂.

Keywords: Acetate; Carbon dioxide; Microbial community regulation; Synergy; Yeast extract.