Harvesting electricity with Geobacter bremensis isolated from compost

• Published in: PloS one Vol. 7; no. 3; p. e34216
• Main Authors: Nercessian, Olivier, Parot, Sandrine, Délia, Marie-Line, Bergel, Alain, Achouak, Wafa
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 28.03.2012; Public Library of Science (PLoS)
• Subjects: Acids; Anodic polarization; Bacteria; Biochemistry; Biochemistry, Molecular Biology; Bioelectric Energy Sources; Biofilms; Biology; Composting; Composts; Consortia; Current density; Dimensionally stable anodes; Earth Sciences; Ecology, environment; Electrodes; Ferric Compounds - chemistry; Gene libraries; Genomic libraries; Geobacter - classification; Geobacter - genetics; Geobacter - isolation & purification; Geobacter - physiology; Graphical representations; Graphite; Harvesting; Life Sciences; Microbiology and Parasitology; Microorganisms; Molecular Sequence Data; Oxidation-Reduction; Phylogenetics; Polymerase chain reaction; Pseudomonas; RNA; RNA, Ribosomal, 16S - chemistry; RNA, Ribosomal, 16S - genetics; rRNA 16S; Soil Microbiology; Species; France; Deltaproteobacteria; Electrochemically active (EA) biofilm; Gammaproteobacteria; Firmicutes
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0034216

Electrochemically active (EA) biofilms were formed on metallic dimensionally stable anode-type electrode (DSA), embedded in garden compost and polarized at +0.50 V/SCE. Analysis of 16S rRNA gene libraries revealed that biofilms were heavily enriched in Deltaproteobacteria in comparison to control biofilms formed on non-polarized electrodes, which were preferentially composed of Gammaproteobacteria and Firmicutes. Among Deltaproteobacteria, sequences affiliated with Pelobacter and Geobacter genera were identified. A bacterial consortium was cultivated, in which 25 isolates were identified as Geobacter bremensis. Pure cultures of 4 different G. bremensis isolates gave higher current densities (1400 mA/m(2) on DSA, 2490 mA/m(2) on graphite) than the original multi-species biofilms (in average 300 mA/m(2) on DSA) and the G. bremensis DSM type strain (100-300 A/m(2) on DSA; 2485 mA/m(2) on graphite). FISH analysis confirmed that G. bremensis represented a minor fraction in the original EA biofilm, in which species related to Pelobacter genus were predominant. The Pelobacter type strain did not show EA capacity, which can explain the lower performance of the multi-species biofilms. These results stressed the great interest of extracting and culturing pure EA strains from wild EA biofilms to improve the current density provided by microbial anodes.