Use of a purified beta-glucosidase from coral-associated microorganisms to enhance wine aroma

BACKGROUND: beta-Glucosidases (3.2.1.21) play essential roles in the removal of nonreducing terminal glucosyl residues from saccharides and glycosides. However, the full potential and different applications of recombinant high-yield microbial beta-glucosidase-producing systems remain to be tackled. RESULTS: A beta-glucosidase gene designated as Mg132 was isolated from a coral microorganism by high-throughput sequencing and functional screening. The deduced amino acid sequences of Mg132 showed a highest identity of 97% with beta-glucosidase predicted in the GenBank database. This gene was cloned and overexpressed in Escherichia coli BL21 (DE3) for the first time. The optimal pH and temperature of purified recombinant Mg132 were 8.0 and 50 degrees C respectively. It exhibited a high level of stability at high concentration of glucose and ethanol, and glucose concentrations below 300 mmol L-1 distinctly stimulated p-nitrophenyl-beta-D-glucopyranoside hydrolysis, reaching 200% at 15% ethanol. The K-m and V-max values were 0.293 mmol L-1 and 320 mu mol min(-1) mg(-1) respectively while using p-nitrophenyl-beta-D-glucopyranoside as a substrate. Wine treated with Mg132 had an obvious positive catalytic specificity for glycosides, which give a pleasant flavor of temperate fruity and floral aromas. The total concentration of fermentative volatiles was 201.42 +/- 10.22 mu g L-1 following Mg132 treatment and 99.21 +/- 7.72 mu g L-1 in control samples. CONCLUSION: Good tolerance of winemaking and aroma fermentative properties suggest that Mg132 has potential application in aroma enhancement in wine and warrants further study. (C) 2021 Society of Chemical Industry.