Knowledge Bank

Depleting worldwide fossil fuels and the political advantages of increasing energy independence motivate research in renewable energy. One important characteristic of a new fuel is the ability to directly replace gasoline within the current infrastructure. Fermentation of sugars into alcohols such as butanol will meet this need. A promising strain of bacteria, clostridium acetobutylicum, converts hexose and pentose sugars into acetone, butanol, and ethanol. Butanol has a high energy density and can directly replace gasoline in combustion engines. For biofuels such as butanol to become a realistic alternative, an abundant source for sugars needs to be used. One potential source is lignocellulose or biomass. Lignocellulose consists of three subcategories of molecules; cellulose, hemicellulose, and lignin. Cellulose is a polymer with glucose subunits and hemicellulose has several types of sugar subunits, mainly pentose. Lignin is made up of different organic compounds which, when broken down, inhibit the growth of clostridium. The main intent of this research is to use different types of fungi to decompose the lignin layer and depolymerize the cellulose. The two types of fungi used were Trichoderma reesei (cellulase producer) and Phanerochaete chrysosporium (lignin decomposer). The two types of fungi were grown on corn fiber, individually and in a co-culture, with the intention to decrease the difficulties of the proceeding hydrolysis and fermentation. The experiment analyzed the ability of the two aforementioned fungi to break down the lignocellulose and lead to fermentable media. The carbohydrates in biomass are an abundant source of stored chemical energy. By finding a way to improve lignocellulosic depolymerization, the technology is available for the downstream processes to make the process economical.