Metataxonomic and metabolic analyses of the syntrophic interactions in the anodic communities in a microbial fuel cell cascade. Anodic communities in a microbial fuel cell

We studied the composition of the microbial community the anodes of a sequence of microbial fuel cells (MFCs) inoculated with a microbial community and continuously fed with a suspension of dried distiller’s grain with solubles (DDGS). The power output of the individual MFCs increased along the cascade with a near doubling of maximum power between the first and final MFC. Sequencing of whole community 16s rRNA genes from the anodic biofilm and the planktonic microbial community revealed a decrease in the abundance of fermentative microorganisms along the cascade, accompanied by an increase in the concentration of fermentation products. Both the decrease in fermentative species and the increase in fermentation products, particularly acetate, significantly correlate with power output. A combined taxonomic, metabolic and chemical analysis suggests a syntrophic relationship between the predominant fermentative bacteria at the first stages of the cascade and the anaerobic respiratory electrogenic community that predominates in the final MFC in the cascade. This syntrophy is explained by the metabolic interaction of the species involved.