Sunday, August 1, 2010
Pacific Concourse (Hyatt Regency San Francisco)
Itaconic acid(metylenesuccinic acid) is a dicarboxylic acid utilized in the manufacture of various synthetic resins. It is biosynthesized as a secondary metabolite by the fungal cells of Aspergillus terreus in a branch of the TCA cycle via decarboxylation of cis-aconitate. In this study, medium optimization was carried out using statistical methods such as full factorial design(FFD), steepest ascent method(SAM) and response surface method(RSM). A synthetic medium(SM) as well as a semi-synthetic medium(SSM) was successfully developed (SM for the investigation of the producers’ fermentation physiology, and SSM for the mass production of itaconic acid in bioreactor cultures, respectively). Notably, it was found that the production level of itaconic acid was strongly negatively affected in both production media by the added phosphate amount, showing that the biosynthetic pattern of itaconic acid follows a typical secondary metabolic pathway. In addition, for development of fermentor-operation strategy for optimal supply of dissolved oxygen(DO), one of the most crucial medium component in mycelia fungal cell fermentations, oxygen mass transfer rate coefficient(kLa) was determined in various modes of impeller-agitation speed(rpm) and O2-sparging rate(vvm) in a 5-liter stirred-bioreactor system. Under the fermentation conditions of sufficient level of dissolved oxygen(200 rpm and 1.5 vvm), production level of itaconic acid was increased by almost 200% in the production medium with the additional components of NaHCO3 and CaCO3.