Abstract
Lactic acid bacteria (LAB) have the potential to produce homoexopolysaccharides (HoPS). Their health benefits and physicochemical properties have been the subject of extensive research. The HoPS functional properties are determined by molecular weight, the type of glycosidic linkages, degrees of branching and chemical composition. The dextransucrases (DSases) produce a kind of HoPS (dextrans), which are among the first biopolymers produced at industrial scale with applications in medicine and biotechnology. The glycodiversification opens additional applications for DSases. Therefore, the design and characterization of new DSases is of prime importance. Previously, we described the isolation and characterization of a novel extracellular dextransucrase (DSR-F) encoding gene. In this study, from DSR-F, we design a novel chimeric dextransucrase DSR-F-∆SP-∆GBD-CBM2a, where DSR-F-∆SP-∆GBD (APY repeats and a CW repeat deleted) was fused to the carbohydrate-binding module (CBM2a) of the β-1-4 exoglucanase/xylanase Cex (Xyn10A) of Cellulomonas fimi ATCC 484. This dextransucrase variant is active and the specificity is not altered. The DSR-F-∆SP-∆GBD-CBM2a was purified by cellulose affinity chromatography for the first time. This research showed that hybrids and chimeric biocatalyst DSases with novel binding capacity to cellulose can be designed to purify and immobilize using renewable lignocellulosic materials as supports.
Highlights
Homoexopolysaccharides (HoPS) produced by lactic acid bacteria (LAB) have been the subject of much research to determine their physicochemical and bioactive properties [1]
The Leuconostoc mesenteroides NRRL B-512F is used for the synthesis of the most common commercial dextran
Based on the 3D structural model of DSR-F-∆SP-∆GBD (Figure 1II), a chimeric dextransucrase fused to the carbohydrate-binding module CBM2a (DSR-F-∆SP-∆GBD-CBM2a) was constructed (Figure 1I,III)
Summary
Homoexopolysaccharides (HoPS) produced by lactic acid bacteria (LAB) have been the subject of much research to determine their physicochemical and bioactive properties [1]. A chimeric dextransucrase from DSR-F-∆SP-∆GBD fused to the carbohydratebinding module (CBM2a) of the exoglucanase/xylanase Cex (Xyn10A) of Cellulomonas fimi ATCC 484 was obtained. This variant, fully active, was purified by cellulose affinity chromatography and partially characterized. This chimeric dextransucrase could be purified or fractionated with sugarcane bagasse or bagasse derivatives and immobilized in those types of renewable supports to produce maltooligosaccharides or modified oligodextrans with potential prebiotic properties
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