Cloning, characterization, and antifungal activity of an endo-1,3-beta-D: -glucanase from Streptomyces sp. S27.

An endo-1,3-beta-D: -glucanase gene, designated as bglS27, was cloned from Streptomyces sp. S27 and successfully expressed in Escherichia coli BL21 (DE3). The full-length gene contains 1,362 bp and encodes a protein of 453 amino acids with a calculated molecular mass of 42.7 kDa. The encoded protein comprises a catalytic module of glycosyl hydrolase family 16, a short glycine linker region, and a family 13 carbohydrate-binding module. The purified recombinant enzyme (BglS27) showed optimal activity at 65 degrees C and pH 5.5 and preferentially catalyzed the hydrolysis of glucans with a beta-1,3-linkage using an endolytic mode of action. The specific activity and K(m) value of BglS27 for laminarin were 236.0 U mg(-1) and 1.89 mg ml(-1), respectively. In antifungal assay, BglS27 had the ability to inhibit the growth of phytopathogenic fungi Rhizoctonic solani and Fusarium oxysporum and some mycotoxin-producing fungi Fusarium crookwellense and Paecilomyces variotii. These favorable properties make BglS27 a good candidate for utilization in biotechnological applications such as plant protection, feed, and food preservation.