A Simple Method To Demonstrate the Enzymatic Production of Hydrogen from Sugar

1270 Journal of Chemical Education • Vol. 75 No. 10 October 1998 • JChemEd.chem.wisc.edu There is current interest in and concern for the development of environmentally friendly bioprocesses whereby biomass and the biodegradable content of municipal wastes can be converted to useful forms of energy. For example, cellulose, a glucose polymer that is the principal component of biomass and paper waste, can be enzymatically degraded to glucose, which can subsequently be converted by fermentation or further enzymatic reaction to fuels such as ethanol or hydrogen. These products represent energy source alternatives to fossil fuels such as oil (1, 2). Demonstration of the relevant reactions in high-school and undergraduate college laboratories would have value not only in illustrating environmentally friendly biotechnology for the utilization of renewable energy sources, such as cellulosic wastes, but could also be used to teach the principles of enzyme-catalyzed reactions. In the experimental protocol described here, it has been demonstrated that the common sugar glucose can be used to produce hydrogen using two enzymes, glucose dehydrogenase and hydrogenase. No sophisticated or expensive hydrogen detection equipment is required—only a redox dye, benzyl viologen, which turns purple when it is reduced (3). The color can be detected by a simple colorimeter. Furthermore, it is shown that the renewable resource cellulose, in its soluble derivative form carboxymethylcellulose, and aspen-wood waste are also sources of hydrogen if the enzyme cellulase is included in the reaction mixture (4 ).