Biocatalytic Hydrolysis of 3‐Hydroxyalkanenitriles to 3‐Hydroxyalkanoic Acids

Abstract

AbstractMicrobial catalysts having a combination of nitrile hydratase and amidase activities had a significantly‐higher specific activity for hydrolysis of 3‐hydroxyalkanenitriles than microbial nitrilase catalysts. Comamonas testosteroni 22–1, Dietzia sp. ADL1 and Comamonas testosteroni 5‐MGAM‐4D nitrile hydratase/amidase biocatalysts each hydrolyzed 3‐hydroxyvaleronitrile to 3‐hydroxyvaleric acid (as the ammonium salt) in 99–100% yields, but in consecutive batch reactions with catalyst recycle, alginate‐immobilized C. testosteroni 5‐MGAM‐4D had superior enzyme stability and volumetric productivity. In a series of 85 consecutive batch reactions with biocatalyst recycle for the production of 1.0 M 3‐hydroxyvaleric acid, the recovered nitrile hydratase and amidase activities in the final reaction were 29% and 40%, respectively, of the initial activities. The catalyst productivity for this series of reactions was 670 g 3‐hydroxyvaleric acid/g dry cell weight (50 g 3‐hydroxyvaleric acid/g biocatalyst bead), and the volumetric productivity of the initial reaction in the series was 44 g 3‐HVA/L/h. Similar results were obtained with alginate‐immobilized C. testosteroni 5‐MGAM‐4D for the hydrolysis of 3‐hydroxybutryonitrile and 3‐hydroxypropionitrile to the corresponding 3‐hydroxyalkanoic acid ammonium salts.