Enzymes from extremophiles operate at conditions that are different from their `normal' counterparts, and are therefore a useful extension of the enzyme toolbox. In this paper, the direct glucosylation reaction mediated by a hyperthermophilic -glucosidase from Pyrocuccus furiosus was investigated. Hexanol was successfully coupled to glucose with this enzyme. A preliminary study was conducted to improve the product yield. A maximum product concentration of 12.9 g.l-1 was attainable by increasing the glucose concentration to the maximum solubility of 2000 g.(kg buffer solution)-1 at the reaction temperature. The highest glucose based yield of 2.64 as achieved with a glucose concentration of 900 g.(kg buffer solution)-1 at a reaction temperature of 65°C and a pH of 6.0. Performing the reaction at higher pH and temperature led to lower product concentrations. This was caused by deactivation of the enzyme accompanied by browning of the reaction mixture. A pH of 4.4 did have a negative effect on both the storage and the operational stability of the enzyme.
de Roode, B. M., van der Meer, T. D., Kaper, T., Franssen, M. C. R., van der Padt, A., van der Oost, J., & Boom, R. M. (2001). The catalytic potency of ß-glucosidase from Pyroccus furiosus in the direct glucosylation reaction. Enzyme and Microbial Technology, 29, 621-624. https://doi.org/10.1016/S0141-0229(01)00441-0