Monday, August 13, 2012
Columbia Hall, Terrace Level (Washington Hilton)
Itaconic acid(IA), a five-carbon unsaturated dicarboxylic acid, was revealed to be biosynthesized as a secondary metabolite by the filamentous fungus, Aspergillus terreus. During intensive strain development process, significant reductions in IA productivity were observed in most of the mutant strains, even with a small increase in the phosphate level of the statistically optimized medium. Therefore, in order to develop IA high-yielding producers having the characteristics of phosphate–deregulation(PD), a rational screening strategy was applied to select mutant strains with higher resistance to sodium arsenate, an phosphate antimetabolite. Rapid strain improvement was possible by adopting an efficient screening strategy based on the sporulation extents of the mutants on PDA solid medium, previously developed in our laboratory. With these rational selection procedures, several mutant cells with up to 60 g/L of IA productivity could be obtained in the newly developed production medium (containing 10-fold higher phosphate level than the previous one). Currently, the stable PD mutants are being tested for industrial applications in 50L and 500L pilot-scale fermentation processes.