Release of soybean isoflavones using a β-Glucosidase from Alicyclobacillus herbarius

β -Glucosidases are used in the food industry to hydrolyse glycosidic bonds in complex sugars, with enzymes sourced from extremophiles better able to tolerate the process conditions. In this work, a novel β-glycosidase from the acidophilic organism  Alicyclobacillus herbarius  was cloned and heterologously expressed in  E. coli  BL21 (DE3).  Ahe GH1 was stable over a broad range of pH values (5-11) and temperatures (4 ºC-55 ºC). The enzyme exhibited excellent tolerance to fructose and good tolerance to glucose, retaining 65% activity in the presence of 10% ( w/v ) glucose. It also tolerated organic solvents, some of which appeared to have a stimulating effect, in particular ethanol with a 1.7-fold increase in activity at 10% ( v/v ). The enzyme was then applied for the cleavage of isoflavone from isoflavone glucosides in an ethanolic extract of soy flour, to produce soy isoflavones which constitute a valuable food supplement, achieving full conversion within 15 min at 30 °C.