Efficient biohydrogen and bioelectricity production from xylose by microbial fuel cell with newly isolated yeast of Cystobasidium slooffiae

Although xylose is the secondary dominant sugar derived from biomass, the conversion of xylose to energy products is quite challenging. In this work, a new exoelectrogenic yeast strain (Cystobasidium slooffiae strain JSUX1) that can generate electricity in microbial fuel cell (MFC) by using xylose as the substrate was isolated and identified. After adaptation, it produced significant current output with rapid xylose metabolism. More surprisingly, this strain produced hydrogen gas either in anerobic flask incubation or in MFC, which delivered a 67 mW/m2 power output and 23 L/m3 hydrogen gas in MFC with xylose as fuel. Further electrochemical analysis indicated that riboflavin was secreted by this strain as the electron mediator for efficient electron transfer between cells and electrode in MFC. This is the first microorganism identified that can simultaneously produce bio-hydrogen and bio-electricity from xylose, which would diversify the toolbox of biomass energy.