Cloning and characterization of α-l-rhamnosidase from Chloroflexus aurantiacus and its application in the production of isoquercitrin from rutin

Objective This study was conducted to characterize recombinant α- l -rhamnosidase from Chloroflexus aurantiacus and apply the enzyme in the production of isoquercitrin from rutin. Results The α- l -rhamnosidase from C. aurantiacus was cloned and expressed in Escherichia coli BL21 and purified as a soluble enzyme. α- l -rhamnosidase purified from C. aurantiacus has a molecular mass of approximately 105 kDa and is predicted to exist as a homodimer with a native enzyme of 200 kDa. The purified enzyme exhibited the highest specific activity for rutin among the reported isoquercitrin producing α- l -rhamnosidases and was applied in the production of isoquercitrin from rutin. Under the optimised conditions of pH 6.0, 50 °C, 0.6 U mL −1 α- l -rhamnosidase, and 30 mM rutin, α- l -rhamnosidase from C. aurantiacus produced 30 mM isoquercitrin after 2 h with a 100% conversion yield and productivity of 15 mM h −1 . Conclusions We achieved a high productivity of isoquercitrin from rutin. Moreover, these results suggest that α- l -rhamnosidase from C. aurantiacus is an effective isoquercitrin producer.