The electron transfer mechanisms of yeast Saccharomyces cerevisiae employing two different mediators, methylene blue (MB) and methyl red (MR), are suggested. The effects of the mediators on Microbial fuel cells (MFCs) performances are investigated when yeast and glucose are the biocatalyst and the substrate, respectively. Yeast tends to stand as floating cell rather than attached to supporting electrode. Therefore, to combine direct and mediated electron transfer mechanisms of yeast, two mediators and carbon felt modified with polyethyleneimine (PEI) (CF-PEI) are adopted and their roles are evaluated. As a result, CF-PEI surface is functionalized with amino groups that can attract and entrap more yeast cells. The cyclic voltammetry (CV) curves representing the mechanisms demonstrate that electron transfer rate constant of MB (0.44 s⁻¹) is higher than MR (0.37 s⁻¹). In addition, the performances of the yeast-MFC adopting MB (429.29 ± 42.75 mW m^-2 at ∼1200 mA m⁻²) are better than those of the yeast-MFC adopting MR and the yeast-MFC without mediator. The reason is that MB is effectively adsorbed by yeast and collects more electrons than MR. These benefits of MB are reflected in a more efficient electron transfer chain and minimize the side reactions deactivating the catalyst.

酵母酿酒酵母的电子转移机理建议使用两种不同的介体，即亚甲基蓝（MB）和甲基红（MR）。当酵母和葡萄糖分别是生物催化剂和底物时，研究了介质对微生物燃料电池（MFCs）性能的影响。酵母倾向于作为漂浮细胞站立，而不是附着在支撑电极上。因此，为了结合酵母的直接和介导的电子传递机制，采用了两种介体和聚乙烯亚胺（PEI）（CF-PEI）修饰的碳毡，并评估了它们的作用。结果，CF-PEI表面被可以吸引和捕获更多酵母细胞的氨基官能化。代表机理的循环伏安法（CV）曲线表明MB（0.44 s ^-1）的电子传递速率常数高于MR（0.37 s^-1）。另外，采用MB的酵母-MFC的性能（ 在〜1200mA m ^-2处为429.29± 42.75mW m ^-2）优于采用MR的酵母-MFC和不具有介体的酵母-MFC的性能。原因是MB被酵母有效地吸收，并且比MR收集更多的电子。MB的这些好处体现在更有效的电子传输链上，并使副反应失活的催化剂减至最少。