Enrichment culture combined with microbial electrochemical enhanced low-temperature anaerobic digestion of cow dung

Abstract

Enrichment culture combined with the microbial electrochemical system was used to co-enhance the low-temperature (20 °C) anaerobic digestion. The results showed that enrichment culture combined with microbial electrochemical system increased the cumulative methane production in low-temperature anaerobic digestion system by 39.64 % and 133.29 % compared to single and no enrichment culture, respectively. Enrichment culture combined with microbial electrochemical system increased the relative abundance of methanogenic archaea (Methanomassiliicoccus, Methanocorpusculum, unclassified Methanomicrobiaceae, Methanobacterium, Methanoculleus, Methanocalculus) and the relative abundance of cold-tolerant hydrolytic acidifying bacteria (unclassified Bacteroidetes, Treponema). The expressions of specific enzyme genes in the methanogenesis pathway were enhanced, including acetyl-CoA synthetase, formylmethanofuran dehydrogenase, methanol cobalamin methyltransferase, etc. These results indicated that enrichment culture combined with microbial electrochemical system enhanced low-temperature anaerobic digestion methanogenesis by altering microbial communities and stimulating enzyme gene expression to affect volatile fatty acids, pH, redox potential, and reducing sugar parameters.