Development of small-size tubular-flow continuous reactors for the analysis of operational stability of enzymes in low-water systems

A very small-scale continuous flow reactor has been designed for use with enzymes in organic media, particularly for operational stability studies. It is constructed from fairly inexpensive components, and typically uses 5 mg of catalyst and flow rates of 1 to 5 mL/h, so only small quantities of feedstock need to be handled. The design allows control of the thermodynamic water activity of the feed, and works with temperatures up to at least 80 degreesC. The reactor has been operated with both nonpolar (octane) and polar (4-methyl- pentan-2-one) solvents, and with the more viscous solvent-free reactant mixture. It has been applied to studies of the operational stability of lipases from Chromobacterium viscosum (lyophilized powder or polypropylene-adsorbed) and Rhizomucor miehei(Lipozyme) in different experimental conditions. Transesterification of geraniol and ethylcaproate has been adopted as a model transformation.