Development of a eukaryotic microbial fuel cell using Arxula adeninivorans

The bulk of microbial fuel cell work has been conducted on prokaryotic microorganisms, with eukaryotes considered too sluggish. Access to the electron transport chain in the mitochondrion appeared to be the limiting factor. There are useful eukaryotic microorganisms yet to be investigated in the microbial fuel cell field. Arxula adeninivorans is a dimorphic yeast with a large substrate range and high osmotic and temperature tolerances making it a good candidate for study in a eukaryotic microbial fuel cell. This thesis demonstrated that A. adeninivorans can participate in both mediated and mediator-less electron transfer in a microbial fuel cell, secreting an electrochemically active substance that contributes to the mediator-less power density when KMnO₄ is used in the cathode as the final electron acceptor. A large number of physical, electrochemical and biological factors were investigated with several novel behaviours reported. Different fuel cell configurations, different electrodes, cell immobilization, different cathode reactions, comparisons to different microorganisms, mixed culture microbial fuel cells and gene over-expression were attempted to both increase electrical output and the understanding of the limitations of eukaryotic microbial fuel cells so that they could be overcome. Research was conducted with A. adeninivorans in a large variety of MFC configurations and conditions to map out future work that would be required to create a model for optimal eukaryotic microbial fuel cell performance

Characterisation of yeast microbial fuel cell with the yeast Arxula adeninivorans as the biocatalyst

International audienceYeast microbial fuel cells have received little attention to date. Yeast should be ideal MFC catalyst because they are robust, easily handled, mostly non-pathogenic organisms with high catabolic rates and in some cases a broad substrate spectrum. Here we show that the non-conventional yeast Arxula adeninvorans transfers electrons to an electrode through the secretion of a reduced molecule that is not detectable when washed cells are first resuspended but which accumulates rapidly in the extracellular environment. It is a single molecule that accumulates to a significant concentration. The occurrence of mediatorless electron transfer was first established in a conventional microbial fuel cell and that phenomenon was further investigated by a number of techniques. Cyclic voltammetry (CV) on a yeast pellet shows a single peak at 450mV, a scan rate study showed that the peak was due to a solution species. CVs of the supernatant confirmed a solution species. It appears that, given its other attributes, A. adeninivorans is a good candidate for further investigation as a MFC catalyst