Monascus kaoliang CBS 302.78 immobilized in polyurethane foam using iso-propanol as co-substrate: Optimized immobilization conditions of a fungus as biocatalyst for the reduction of ketones

Monascus kaoliang was selected after a microbial screening as a highly active and selective whole cell catalyst for the reduction of ketones. In the present paper we describe the optimum growing conditions and an interesting immobilization procedure by adsorption in polyurethane foams (PUFs). This methodology is easy to perform and the immobilized catalyst is active, stable and reusable. The use of different co-substrates for cofactor regeneration was also tested and iso-propanol (i-PrOH) was found as the best co-substrate, as it leads to a catalyst reusable for 17 cycles, displaying better NADH regeneration properties than others e.g., glucose (10 cycles) or saccharose (6 cycles). The reduction of different prochiral ketones showed that the ketone reductase activity of this mould follows the Prelog’s rule and kinetic experiments demonstrated that the process follows a pseudo-first kinetic order.