A novel cold-adapted and glucose-tolerant GH1 β-glucosidase from Exiguobacterium antarcticum B7

A novel GH1 beta-glucosidase (EaBgl1 A) from a bacterium isolated from Antarctica soil samples was recombinantly overexpressed in Escherichia coil cells and characterized. The enzyme showed unusual pH dependence with maximum activity at neutral pH and retention of high catalytic activity in the pH range 6 to 9, indicating a catalytic machinery compatible with alkaline conditions. EaBgl1 A is also a coldadapted enzyme, exhibiting activity in the temperature range from 10 to 40 degrees C with optimal activity at 30 degrees C, which allows its application in industrial processes using low temperatures. Kinetic characterization revealed an enzymatic turnover (K-cat) of 6.92s(-1) (cellobiose) and 32.98 s(-1) (pNPG) and a high tolerance for product inhibition, which is an extremely desirable feature for biotechnological purposes. Interestingly, the enzyme was stimulated by up to 200mM glucose, whereas the commercial cocktails tested were found fully inhibited at this concentration. These properties indicate EaBgl1A as a promising biocatalyst for biotechnological applications where low temperatures are required. (c) 2015 Elsevier B.V. All rights reserved.