Synthesis of alkyl glucosides catalyzed by immobilized α-amylase from Thermotoga maritima

Abstract

The enzymatic production of alkyl glucosides is limited by the stability of the enzymes in the presence of alcohols. In the present study, we investigated three different supports: Sepharose 4B, crosslinked Sepharose (Fast Flow), and Eupergit C for the immobilization of -amylase from Thermotoga maritima, AmyA, to increase its stability during the alcoholysis reaction. The enzyme immobilized on crosslinked Sepharose showed the best results, allowing its reutilization for at least five cycles while maintaining more than 50% residual activity. In addition, the immobilization of a previously reported H222Q variant resulted in a superior transglycosidic activity (> 50%) when compared to that of the wild-type (WT) AmyA. Moreover, both versions of the enzyme increased their residual activity after 24 h of incubation at 85{degrees}C upon immobilization. The alcoholysis with n-butanol, n-hexanol, and n-octanol was investigated to optimize the reaction conditions. Here, the addition of DMSO had a positive effect on the alcoholysis reactions with AmyA WT, achieving a total octyl glucoside title 1.75-fold higher than that obtained in the absence of DMSO. ImportanceAlkyl glucosides are valuable, non-toxic surfactants primarily synthesized chemically. The development of biocatalysts for their production has become a significant goal in the field of biocatalysis to avoid the disposal of toxic waste and environmentally harmful processes. To make these processes competitive, the use of low-cost raw materials and the recycling of biocatalysts are essential. The immobilization of Thermotoga maritima -amylase has enabled its use in the presence of long-chain alcohols, achieving octyl glucoside production of 0.7 mg/mL--an unprecedented feat for an amylase. This study represents a breakthrough in the use of -amylases for alkyl glucoside production.