Traditional beverage pulque yeast isolates for potential application in microbial electrochemical technologies using corn cooking industry effluents as substrate

Abstract

Purpose In this work, exoelectrogenic potential of the yeasts isolated from traditional beverage in Mexico (pulque) in an MFC when corn cooking industry effluent (CCIE) is used as substrate. Methods The yeasts were isolated in YPD and a screening was carried out with a sugar assimilation test, selecting the CR4 isolate for the bioelectrochemical tests. For these studies, CR4 was inoculated into a double-chamber MFC containing a carbon cloth anode treated with H2SO4. YPD, CCIE and CCIE + NaCl were used as electrolyte. The i0, Rct and Rmt were calculated by fitting polarization curves using the Butler-Volmer kinetic model. Results Electrochemical studies revealed the ability of CR4 to transfer electrons to a chemically treated anode. The control MFCs obtained the highest electronic transfer rate by having i0 values close to 1.01 x 10 − 4 A and low Rct values compared to the other treatments (255.28 Ω). When using the CCIE treatment, the resistance increased (664.55 Ω) due to the complexity of assimilation of the substrate, giving rise to low values of biomass in the electrode (0.11 mg/mL). The CCIE + NaCl treatment improved the output voltage, however, resistance increased, probably due to the low availability of the substrate since the resistance to mass transfer (Rmt) reached values of up to 1007.55 Ω. Conclusions These results will help to understand the behavior of yeasts in bioelectrochemical systems, improving the future development of microbial electrochemical technologies applied to effluent treatment.