Promiscuous Glucose Oxidase: Electrical Energy Conversion of Multiple Polysaccharides Spanning Starch and Dairy Milk

Enzymatic biofiiel cells (EFCs) are devices that are capable of producing electrical energy from the enzymatic oxidation of simple, energy-dense fuels (such as sugars and alcohols). Glucose oxidase (G0x) is perhaps the most widely used enzyme at the bioanode of EFCs, affording devices that can be fueled by glucose. Due to its high substrate specificity, GOx was initially employed in glucose biosensor applications, which later translated into EFC technology. This high substrate specificity, however, often restricts EFC devices to operation on single fuels. Herein, we report the use of a commercial GOx with greater substrate promiscuity (broader substrate G0x, bG0x), which can result in the fabrication of EFCs that can utilize a single versatile catalyst for the oxidation of many mono-, di-, tri-, and polysaccharides. The EFCs presented within this study were fueled by glucose, maltose, maltotriose, cellobiose, lactose, galactose, and xylose. Additionally, the ability for the same biocatalyst to oxidize sugars from alternative sources was investigated, with EFCs producing electrical energy from lactose within dairy milk (0.43 +/- 0.01 mA cm(-2) and 80.1 +/- 1.2 /4W cm(-2)) and starch solutions (0.19 +/- 0.00 rnA cm(-2) and 50.9 +/- 0.9 mu W cm(-2)).