Extracellular electron transfer in yeast-based biofuel cells: A review

• Up-to-date research and development on yeast-based biofuel cells are reviewed.
• Power densities from 20 to 2440 mW/m2 are reported.
• EET mechanisms in the presence and absence of exogenous mediators are summarized.
• Evidences for contribution of aerobic respiration to EET are presented.
• Strategies for improvement of EET and electrical outputs are discussed.

This paper reviews the state-of-the art of the yeast-based biofuel cell research and development. The established extracellular electron transfer (EET) mechanisms in the presence and absence of exogenous mediators are summarized and discussed. The approaches applied for improvement of mediator-less yeast-based biofuel cells performance are also presented. The overview of the literature shows that biofuel cells utilizing yeasts as biocatalysts generate power density in the range of 20 to 2440 mW/m2, which values are comparable with the power achieved when bacteria are used instead. The electrons' origin and the contribution of the glycolysis, fermentation, aerobic respiration, and phosphorylation to the EET are commented. The reported enhanced current generation in aerobic conditions presumes reconsideration of some basic MFC principles. The challenges towards the practical application of the yeast-based biofuel cells are outlined.