title: The role of riboflavin in decolourisation of Congo red and bioelectricity production using Shewanella oneidensis-MR1 under MFC and non-MFC conditions.
abstract: Dissimilatory metal reducing bacteria can exchange electrons extracellularly and hold great promise for their use in simultaneous wastewater treatment and electricity production. This study investigated the role of riboflavin, an electron carrier, in the decolourisation of Congo red in microbial fuel cells (MFCs) using Shewanella oneidensis MR-1 as a model organism. The contribution of the membrane-bound protein MtrC to the decolourisation process was also investigated. Within the range of riboflavin concentrations tested, 20 µM was found to be the best with >95% of the dye (initial concentration 200 mg/L) decolourised in MFCs within 50 h compared to 90% in the case where no riboflavin was added. The corresponding maximum power density was 45 mW/m2. There was no significant difference in the overall decolourisation efficiencies of Shewanela oneidensis MR-1 ΔMtrC mutants compared to the wild type. However, in terms of power production the mutant produced more power (Pmax76 mW/m2) compared to the wild type (Pmax46 mW/m2) which was attributed to higher levels of riboflavin secreted in solution. Decolourisation efficiencies in non-MFC systems (anaerobic bottles) were similar to those under MFC systems indicating that electricity generation in MFCs does not impair dye decolourisation efficiencies. The results suggest that riboflavin enhances both decolourisation of dyes and simultaneous electricity production in MFCs.
authors.affiliation: Microbiology Department, National Center for Radiation Research and Technology (NCRRT), Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt. ola_gomaa@hotmail.com.
authors.forename: Ola M
authors.initials: OM
authors.lastname: Gomaa
authors.affiliation: Department of Life Sciences, University of Westminster, London, UK.
authors.forename: Segun
authors.initials: S
authors.lastname: Fapetu
authors.affiliation: Department of Life Sciences, University of Westminster, London, UK.
authors.forename: Godfrey
authors.initials: G
authors.lastname: Kyazze
authors.affiliation: Department of Life Sciences, University of Westminster, London, UK.
authors.forename: Tajalli
authors.initials: T
authors.lastname: Keshavarz
mesh_terms: D001673:Biodegradation, Environmental; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D003224:Congo Red / Q000737:chemistry*; D003574:Cytochrome c Group / Q000378:metabolism*; D004560:Electricity; D004566:Electrodes / Q000382:microbiology; D012256:Riboflavin / Q000378:metabolism*; D020592:Shewanella / Q000502:physiology*; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology
chemical_list: D003224:Congo Red; D003574:Cytochrome c Group; D012256:Riboflavin; D062065:Wastewater; C433527:MtrC protein, Shewanella
keywords: Dye decolourisation; Electron shuttling; Energy production; MtrC; Riboflavin; Shewanella