Nicotinic acid bioproduction in UF-membrane reactor via a nitrile hydratase amidase catalyzed reaction

In this study Microbacterium imperiale CBS 498-74 resting cells are used as catalyst for the bioconversion of 3-cyanopyridine into nicotinic acid. Nitrile bioconversion into the corresponding acid is performed by this strain via a two step cascade reaction catalysed by nitrile hydratase and amidase with an amide as intermediate. Both enzymes that operate under mild conditions suitable for the synthesis of labile organic molecules have been characterized independently for activity and stability in a UF-membrane bioreactor. The reactor was fed with buffered solutions of appropriate substrate, either 3-cyanopyridine or nicotinamide. The effluent containing unreacted substrate, products and buffer were collected and analysed for product determination. The operational conditions (temperature, residence time) that strongly influence continuous UFmembrane bioreactor performances (conversion yield and selectivity) are presented