Intensification of biocatalytic processes by using alternative reaction media

Performances of biocatalytic processes in industry are often limited by productivity, product concentration and biocatalyst stability. Reasons can be such as unfavourable reaction thermodynamics, low water solubility of the substrates or inhibition caused by high substrate or product concentrations. A way to overcome these limitations and to enhance economic competitiveness of the process can be process intensification (PI) using an alternative reaction medium. Very early in industrial biotransformation processes, it was shown that many interesting target products of organic synthesis are much more soluble and sometimes even more stable in non-conventional reaction media than in buffered aqueous solutions. Moreover, the absence of water is also generally desired to prevent side and degradation reactions as well as microbial contamination, which in turn eliminates the need to work under sterile conditions thereby reducing energy expenditure. In addition, it was also discovered early on that solvents can influence the activity and stability of enzymes quite differently depending on their water affinity and thus if they form rather monophasic or biphasic systems with the latter.