Yeast Extract as an Effective and Safe Mediator for the Baker’s-Yeast-Based Microbial Fuel Cell

Although utilizing the exogenous mediators distinctly enhances the microbial fuel cell (MFC) performance, possibility of microorganisms’ toxicity, environmental aspect and cost are the main dilemmas facing wide applications. Therefore, successful applying of the yeast extract as a mediator in the baker’s-yeast-based (Saccharomyces cerevisiae-based) MFCs would be of great interest as it will overcome all the aforementioned problems. The influence of the yeast extract addition was investigated based on the yeast cell adhesion on the surface of plain and gold-sputtered carbon paper anodes. In the case of plain carbon paper, the addition of the yeast extract considerably enhanced the performance of the yeast-based MFC, which can be attributed to the yeast extract role as growth media or as a mediator; the current and power densities increased from 94 to 190 mA/cm2 and from 12.9 to 32.6 mW/cm2, respectively. However, compared with the plain carbon paper, in the case of gold-sputtered anode the performance significantly increased with yeast extract addition, whereas it drastically decreased without yeast extract; the current and power densities increased from 25 to 300 mA/cm2 and from 2 to 70 mW/cm2, respectively. The obtained results indicated that yeast extract can be exploited as an effective mediator in the Saccharomyces cerevisiae-based MFCs.