Biotransformations

Abstract

Biotransformations using enzymes and whole microbial cells have been used for centuries to produce foods and beverages. However, only in the last century we have developed methods to understand and improve biocatalyst stability and productivities. Engineering and directed evolution of enzymes have enhanced enzymatic activity and increased the number of products obtainable by biotransformation. The understanding of the mechanisms of cellular adaptation to environmental conditions also allowed the use of microbial cells in nonaqueous biocatalytic systems. Both free and immobilized enzymes and microorganisms have been used successfully in different media, including aqueous, aqueous:organic and organic solvents, gas:solid systems, supercritical fluids, and ionic liquids. Extremophiles also contributed significantly to the development of biotransformation processes, as they are a source of enzymes able to work in environments of extreme temperature, pH, and ionic strength. Chiral compounds to be used as agrochemicals, pharmaceuticals, fragrances, and as food additives can easily be synthesized by biotransformation, usually under mild conditions when compared with chemical synthesis. Kinetic resolutions of racemic substances are becoming common and successful processes. The application of biotransformations in industrial processes further elucidates the success of using enzymes and microbial cells for the production of commercially interesting compounds.