USE OF A GENETIC ALGORITHM IN THE DEVELOPMENT OF A SYNTHETIC GROWTH-MEDIUM FOR ARTHROBACTER SIMPLEX WITH HIGH HYDROCORTISONE DELTA(1)-DEHYDROGENASE ACTIVITY

The production process for Arthrobacter simplex with high specific hyd rocortisone Delta(1)-dehydrogenase activity was improved by medium opt imization in parallel shake flask experiments. Using a genetic algorit hm, the concentrations of 12 medium components (mineral salts and amin o acid) were optimized within 144 experiments to give maximum specific hydrocortisone Delta(1)- dehydrogenase activity and biomass yield (fu ll experimental plan: 1.5 x 10(14) experiments). The specific hydrocor tisone Delta(1)-dehydrogenase activity was improved by a factor of 4.5 to 1800 U g(-1). With the optimized medium composition in a stirred t ank reactor for batch production of A. simplex, a specific hydrocortis one Delta(1)-dehydrogenase activity of 2000-3000 U g(-1) dry biomass w as achieved depending on harvest time (previously reported data: 18-37 U g(-1)).