title: Segregation of the Anodic Microbial Communities in a Microbial Fuel Cell Cascade.
abstract: Metabolic interactions within microbial communities are essential for the efficient degradation of complex organic compounds, and underpin natural phenomena driven by microorganisms, such as the recycling of carbon-, nitrogen-, and sulfur-containing molecules. These metabolic interactions ultimately determine the function, activity and stability of the community, and therefore their understanding would be essential to steer processes where microbial communities are involved. This is exploited in the design of microbial fuel cells (MFCs), bioelectrochemical devices that convert the chemical energy present in substrates into electrical energy through the metabolic activity of microorganisms, either single species or communities. In this work, we analyzed the evolution of the microbial community structure in a cascade of MFCs inoculated with an anaerobic microbial community and continuously fed with a complex medium. The analysis of the composition of the anodic communities revealed the establishment of different communities in the anodes of the hydraulically connected MFCs, with a decrease in the abundance of fermentative taxa and a concurrent increase in respiratory taxa along the cascade. The analysis of the metabolites in the anodic suspension showed a metabolic shift between the first and last MFC, confirming the segregation of the anodic communities. Those results suggest a metabolic interaction mechanism between the predominant fermentative bacteria at the first stages of the cascade and the anaerobic respiratory electrogenic population in the latter stages, which is reflected in the observed increase in power output. We show that our experimental system represents an ideal platform for optimization of processes where the degradation of complex substrates is involved, as well as a potential tool for the study of metabolic interactions in complex microbial communities.
authors.affiliation: Department of Microbial and Cellular Sciences, University of Surrey Guildford, UK.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Hodgson
authors.affiliation: Cardiff School of Biosciences, Cardiff University Cardiff, UK.
authors.forename: Ann
authors.initials: A
authors.lastname: Smith
authors.affiliation: Department of Microbial and Cellular Sciences, University of Surrey Guildford, UK.
authors.forename: Sonal
authors.initials: S
authors.lastname: Dahale
authors.affiliation: Warwick Integrative Synthetic Biology Centre, University of Warwick Coventry, UK.
authors.forename: James P
authors.initials: JP
authors.lastname: Stratford
authors.affiliation: Centre for Digestive and Gut Health, Department of Surgery and Cancer, Imperial College LondonLondon, UK; Division of Computational and Systems Medicine, Department of Surgery and Cancer, Imperial College LondonLondon, UK.
authors.forename: Jia V
authors.initials: JV
authors.lastname: Li
authors.affiliation: Department of Computer Science, University of Surrey Guildford, UK.
authors.forename: André
authors.initials: A
authors.lastname: Grüning
authors.affiliation: Department of Microbial and Cellular Sciences, University of Surrey Guildford, UK.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Bushell
authors.affiliation: Cardiff School of Biosciences, Cardiff UniversityCardiff, UK; Centre for Digestive and Gut Health, Department of Surgery and Cancer, Imperial College LondonLondon, UK.
authors.forename: Julian R
authors.initials: JR
authors.lastname: Marchesi
authors.affiliation: Department of Microbial and Cellular Sciences, University of Surrey Guildford, UK.
authors.forename: C
authors.initials: C
authors.lastname: Avignone Rossa
keywords: anodic biofilms; electroactive bacteria; metabolite profiling; metagenomic analysis; microbial communities; microbialfuel cells