Purification and Partial Characterization of a β-1, 3-Glucanase Secreted by the Mycoparasite Stachybotrys elegans

Abstract

A β-1, 3-glucanase secreted by Stachybotrys elegans, when grown on minimal synthetic medium containing Rhizoctonia solani cell wall fragments, was purified to homogeneity. The purification method involved ammonium sulfate precipitation and ion-exchange and size-exclusion chromatographies. The molecular mass of the enzyme was estimated under denaturing conditions to be about 94 kDa. The enzyme had an optimum pH of 5.0 and was most active between 40 and 50°C. Except for Mn²⁺, the enzyme activity was not sensitive to the metal ions tested and K_m of 0.18mg/ml was estimated for laminarin as a substrate. Cell wall lytic activity of purified β-1, 3-glucanase was tested on actively growing R. solani hyphae. β-1, 3-Glucanase induced morphological changes such as hyphal tip swelling, bursting, leakage of cytoplasm, and formation of numerous septae