Sunday, August 11, 2013
Pavilion (Sheraton San Diego)
Studies on the production of itacoic acid(IA) biosynthesized as a secondary metabolite by the filamentous fungus, Aspergillus terreus, have been carried out. IA is utilized as a co-monomer for manufacturing various polymers such as rubbers, paints, and chemical resins. In this study, for enhancing IA production, the gene coding for cis-aconitic acid decarboxylase(CAD), and mstE gene for a low affinity glucose transporter were introduced into the high-yielding phosphate-deregulated(PD) mutants of A. terreus showing higher resistance to sodium arsenate, an phosphate antimetabolite. With this rational strain improvement procedure, recombinant cells with up to 60g/L of IA productivity could be obtained (almost 2 times higher productivity than the parallel non-recombinant mutant strains). Rapid strain improvement was possible by adopting an efficient screening strategy based on the sporulation extents of the recombinant mutants on PDA solid medium, previously developed in our laboratory. Optimized production medium was also developed suitable for the newly developed recombinant mutants through the statistical methods such as Plackett-Burman design, fractional factorial design(FFD), steepest ascent method(SAM), and finally response surface methods(RSM). Various fermentation results obtained from 5L bioreactor operations with the new high-yielding recombinants will be presented in this paper as well.