Purification and functional characterization of the first stilbene glucoside-specific β-glucosidase isolated from Lactobacillus kimchi

• First stilbene glucoside-specific β-glucosidase from lactic acid bacterium.
• Stilbene glucoside-specific enzyme showed various stilbene glucosides.
• The enzyme showed the highest activity to methoxy stilbene, isorhaponticin.
• The enzyme converted polydatin into resveratrol as 100% yield.
• The enzyme was effectively used in production of bioactive compounds.

This study aimed to develop viable enzymes for bioconversion of resveratrol-glucoside into resveratrol. Out of 13 bacterial strains tested, Lactobacillus kimchi JB301 could completely convert polydatin into resveratrol. The purified enzyme had an optimum temperature of 30–40 °C and optimum pH of pH 5.0 against polydatin. This enzyme showed high substrate specificities towards different substrates in the following order: isorhaponticin >> polydatin >> mulberroside A > oxyresveratrol-3-O-glucoside. Additionally, it rarely hydrolyzed astringin and desoxyrhaponticin. Based on these catalytic specificities, we suggest this enzyme be named stilbene glucoside-specific β-glucosidase. Furthermore, polydatin extracts from Polygonum cuspidatum were successfully converted to resveratrol with a high yield (of over 99%). Stilbene glucoside-specific β-glucosidase is the first enzyme isolated from lactic acid bacteria capable of bio-converting various stilbene glucosides into stilbene.