|Peterson, Stephen - Steve|
Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 5/9/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Using ethanol as an alternative to petroleum based fuels significantly reduces automobile emissions and requires few alternations in current vehicle technology to be implemented. Sugar beet pulp (SBP), an agricultural co-product of the table sugar industry, shows promise as a substrate for microbial fermentations to ethanol. Sugar beet pulp is rich in cellulose, hemicellulose, and pectin that serve as carbohydrate sources for microbial fermentative metabolism. However, these carbohydrate polymers must be degraded to their simple sugar subunits in order to be used by fermenting microorganisms that often lack some or all of the enzymatic activities. Commercially available fungal enzymes digest SBP, although they are an expensive component of the bioconversion process. Experiments were conducted to determine the amount of ethanol produced from various combinations of commercially available fungal enzymes with genetically engineered ethanologenic Escherichia coli as biocatalysts. In an effort to reduce the amount of commercially available fungal enzymes needed to produce over 30 g ethanol/liter, the pulp was subjected to two different chemical pretreatments. Ammonia pressurization depressurization (APD) pretreatment did not increase enzymatic hydrolysis of the sugar beet pulp. Dilute acid hydrolysis of sugar beet pulp was also evaluated in an effort to open plant fibers and enhance enzymatic degradation of the pulp. Under chemical pretreatment conditions examined, fungal enzymes are still required to further degrade the beet pulp into monomers. In addition to commercially available fungal enzymes, crude culture filtrates were used in SBP fermentations. Strains of Aspergillus niger, supplied by the USDA-ARS, were screened for cellulase and pectinase activities on solid media.