A general strategy to synthesis chitosan oligosaccharide-O-Terpenol derivatives with antibacterial properties

The objectives of the present study are to synthesize a series of chitosan oligosaccharide-O-Terpenol (COS-O-Ter) derivatives and their implication to evaluate in vitro antibacterial activity. Herein, a general strategy is described for preparing COS-O-Ter derivatives, including substitution and deprotection reactions. The structures of COS-O-Ter derivatives were characterized by FT-IR, ¹H NMR, XRD, TGA, and elemental analysis. COS-O-Ter derivatives revealed the excellent solubility and in vitro antibacterial activity. Moreover, their antibacterial activities were more sensitive to Staphylococcus aureus (S. aureus) than Escherichia coli (E. coli) indicating the effective potential application of COS-O-Ter derivatives as natural antibacterial agents. The aforementioned study opens a pave to expand the application scope of COS and its derivatives in the food and pharmaceutical industries.

Improving an Escherichia coli-based biocatalyst for terpenol glycosylation by variation of the expression system

Glycosides are becoming increasingly more relevant for various industries as low-cost whole-cell-biocatalysts are now available for the manufacture of glycosides. However, there is still a need to optimize the biocatalysts. The aim of this work was to increase the titre of terpenyl glucosides in biotransformation assays with E. coli expressing VvGT14ao, a glycosyltransferase gene from grape (Vitis vinifera). Seven expression plasmids differing in the resistance gene, origin of replication, promoter sequence, and fusion protein tag were generated and transformed into four different E. coli expression strains, resulting in 18 strains that were tested for glycosylation efficiency with terpenols and a phenol. E. coli BL21(DE3)/pET-SUMO_VvGT14ao yielded the highest titres. The product concentration was improved 8.6-fold compared with E. coli BL21(DE3)pLysS/pET29a_VvGT14ao. The selection of a small solubility-enhancing protein tag and exploitation of the T7 polymerase-induction system allowed the formation of increased levels of functional recombinant protein, thereby improving the performance of the whole-cell biocatalyst.