Exploring Providencia rettgeri for application to eco-friendly paper based microbial fuel cell.

We report results of the studies relating to improved stability (40 days) of small sized microbial fuel cell (MFC) fabricated using agarose embedded paper-based proton exchange membrane. A fermentative bacterium Providencia rettgeri was isolated from rotten potato slurry and identified by 16S rRNA sequencing. The electroactivity of the bacteria was monitored via chronoamperometric and cyclic voltammetric studies using a three-electrode system which indicated the presence of bacterial redox mediator. The Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) and UV-Vis absorption spectroscopy provided the evidence that Providencia rettgeri synthesized folate (vitamin B) during fermentation that was found to act for the first time as a redox mediator in an MFC. The paper based designed MFC fed with Providencia rettgeri yielded open circuit voltage of 787.9 mV with power and current density of 5.02 W/m and 11.26 A/m, respectively when measured across 10 kΩ. The microbial re-chargeable battery comprising of an assembly of parallelly aligned four units of MFCs when connected in series (total 16 MFCs), generated 1.5 V that was used for powering a red-light emitting device (LED).