A novel ecological role of the Firmicutes identified in thermophilic microbial fuel cells.
|Title||A novel ecological role of the Firmicutes identified in thermophilic microbial fuel cells.|
|Publication Type||Journal Article|
|Year of Publication||2008|
|Authors||Wrighton KC, Agbo P, Warnecke F, Weber KA, Brodie EL, DeSantis TZ, Hugenholtz P, Andersen GL, Coates JD|
|Journal||The ISME journal|
|Date Published||2008 Nov|
|Keywords||Bioelectric Energy Sources, DNA, Bacterial, DNA, Ribosomal, Electricity, Genes, rRNA, Gram-Positive Bacteria, Hot Temperature, Microarray Analysis, Molecular Sequence Data, Phylogeny, RNA, Bacterial, RNA, Ribosomal, 16S, Sequence Analysis, DNA, Sequence Homology, Nucleic Acid|
Significant effort is currently focused on microbial fuel cells (MFCs) as a source of renewable energy. Most studies concentrate on operation at mesophilic temperatures. However, anaerobic digestion studies have reported on the superiority of thermophilic operation and demonstrated a net energy gain in terms of methane yield. As such, our studies focused on MFC operation and microbiology at 55 degrees C. Over a 100-day operation, these MFCs were stable and achieved a power density of 37 mW m(-2) with a coulombic efficiency of 89%. To infer activity and taxonomic identity of dominant members of the electricity-producing community, we performed phylogenetic microarray and clone library analysis with small subunit ribosomal RNA (16S rRNA) and ribosomal RNA gene (16S rDNA). The results illustrated the dominance (80% of clone library sequences) of the Firmicutes in electricity production. Similarly, rRNA sequences from Firmicutes accounted for 50% of those taxa that increased in relative abundance from current-producing MFCs, implying their functional role in current production. We complemented these analyses by isolating the first organisms from a thermophilic MFC. One of the isolates, a Firmicutes Thermincola sp. strain JR, not only produced more current than known organisms (0.42 mA) in an H-cell system but also represented the first demonstration of direct anode reduction by a member of this phylum. Our research illustrates the importance of using a variety of molecular and culture-based methods to reliably characterize bacterial communities. Consequently, we revealed a previously unidentified functional role for Gram-positive bacteria in MFC current generation.
|Alternate Journal||ISME J|