Biochemical characterization of a lichenase from Penicillium occitanis Pol6 and its potential application in the brewing industry

The purification and characterization of an extracellular lichenase from the fungus Penicillium occitanis Pol6 were studied. The strain produced the maximum level of extracellular lichenase (45 +/- 5 U ml(-1)) when grown in a medium containing oat flour (2%, w/v) at 30 degrees C for 7 days. The purified enzyme EG(L) showed as a single protein band on SDS-PAGE with a molecular mass of 20 kDa. Its N-terminal sequence of 10 amino acid residues was determined as LDNGAPLLNV. The purified enzyme showed an optimum activity at pH 3.0 and 50-60 degrees C. The half-lives of EG(L) at 60 degrees C and 70 degrees C were 80 min and 21 min, respectively. Substrate specificity studies revealed that the enzyme is a true beta-1,3-1,4-D-glucanase. The enzyme hydrolyzed lichenan to yield trisaccharide, and tetrasaccharide as the main products. Under simulated mashing conditions, addition of EG(L) (20 U/ml) or a commercial beta-glucanase (20 U/ml) reduced the filtration time (25% and 21.3%, respectively) and viscosity (10% and 8.18%, respectively). These characteristics indicate that EG(L) is a good candidate in the malting and brewing industry. (C) 2014 Elsevier Ltd. All rights reserved.