Methylene blue as an exogenous electron mediator on bioelectricity from molasses using Meyerozyma guilliermondii as biocatalyst

Abstract

A microbial fuel cell (MFC) is a biochemical cell which is able to transform the chemical energy in organic or inorganic substrates into electrical energy through biochemical pathways. The current study explained the role of methylene blue (MB) as an exogenous electron mediator on the efficiency of bioelectricity generation from sugarcane molasses as a substrate by an anode respiring yeast (biocatalyst) via a microbial fuel cell technology. An anode respiring yeast was isolated from sugarcane molasses and was identified according to 18S rRNA as Meyerozyma guilliermondii STRI3 with accession number in GenBank (KP764968). The results showed that methylene blue (MB) enhances the power generation in comparison with power output without MB. The maximum power density (Pmax) and the current density (ID) of the MFC with MB as an exogenous mediator achieved 94 ± 0.9 mW/m2 and 300 mA/m2, which consider higher than MFC without MB (27.9 ± 0.9 mW/m2 and 142 mA/m2, respectively). The COD removal reached 56% at 830 mg/L, while it was 15% at 3045 mg/L after 7 days of MFC operation. These presented results suggested the potentiality of electricity generation by M. guilliermondii STRI3 as a biocatalyst from sugarcane molasses using MB as an electron mediator. The finding of this work proposes the use of M. guilliermondii and MB as an exogenous mediator as a new way to increase the performance of the MFC for further applications.