Simplified Technology for Enzyme Production with Thermophilic Anaerobic Bacteria

The biological conversion of agricultural and forestry biomass into value-added chemicals offers great promise for increasing industrial sustainability, however technological limitations still exist. Enzymes are an important component of this growing technology, but in many cases the cost of enzymes is prohibitively expensive when compared to more traditional methods. For instance, biofuel production is currently not cost effective without government subsidies. The National Renewable Energy Laboratory Ethanol Project has stated that "enzyme technology offers the greatest opportunity for future cost reduction in biofuel production" and has identified cellulase production as a high priority for research and development. Our proposal links (1) a new, value-added use for under-utilized agricultural co-products with (2) a novel method for supplying enzymes for biofuel and biochemical production. This process should result in a less-expensive method for producing such chemicals and lessen the nation's dependence on foreign energy supplies. The results are transferable to other processing industries that use enzymes, such as biochemicals, animal feeds, paper processing, beverage alcohols, and detergent additives. The overall project goal is to evaluate the feasibility of using solid-state cultivation (SSC) of anaerobic, thermophilic bacteria to produce low-cost thermostable enzyme complexes (e.g. cellulases) from agricultural residues. This approach is novel because we will use organisms that inherently overcome the technical problems usually associated with SSe. In addition, we are approaching the problem with a multi-disciplinary team with expertise in biosystems and agricultural engineering, microbiology, and agricultural economics. The project objectives are to 1) develop techniques for producing bacterial biomass using anaerobic solidstate cultivation at high temperatures; 2) characterize the specific enzymes associated with the bacterial biomass; 3) evaluate the performance of enzymes produced from solid-state cultures as biocatalysts for cellulose degradation (saccharification); and 4) evaluate the economics of producing thermostable enzymes by SSC versus traditional methods. A variety of anaerobic, thermophilic bacteria will be screened for growth and multiple enzyme production using several agriculturaVprocessing residues. A comparison of the saccharification ability of SSC-derived enzyme complexes versus the more traditionally used enzymes from liquid culture will be performed. The economics of producing thermostable enzymes using SSC will be analyzed and compared to the current method of enzyme production, specifically for biofuels.