How to overcome limitations in biotechnological processes - examples from hydroxynitrile lyase applications

During the last decades, enzymes became very versatile catalysts for a variety of reactions including natural and unnatural compounds. However, many enzyme-catalysed reactions suffer from diverse restrictions because of limitations related to process parameters or the enzyme. The understanding and overcoming of those undesired side effects is therefore mandatory for the implementation of optimal process parameters. To achieve this aim, various methods from molecular biology and reaction engineering can be employed. By focusing on the hydroxynitrile lyase-catalysed synthesis of enantiopure cyanohydrins, we give an overview of strategies to improve commercially utilized enzymes and to suppress non-enzymatic reactions. Particular emphasis is placed on the necessity to combine approaches from different fields, such as enzyme engineering and reaction engineering.