PURIFICATION AND PARTIAL CHARACTERIZATION OF A BETA-1,S-GLUCANASE SECRETED BY THE MYCOPARASITE STACHYBOTRYS ELEGANS

A beta-1,3-glucanase secreted by Stachybotrys elegans, when grown on m inimal synthetic medium containing Rhizoctonia solani cell wall fragme nts, was purified to homogeneity. The purification method involved amm onium sulfate precipitation and ion-exchange and size-exclusion chroma tographies. The molecular mass of the enzyme was estimated under denat uring conditions to be about 94 kDa. The enzyme had an optimum pH of 5 .0 and was most active between 40 and 50 degrees C. Except for Mn2+, t he enzyme activity was not sensitive to the metal ions tested and K-m of 0.18 mg/ml was estimated for laminarin as a substrate. Cell wall ly tic activity of purified beta-1,3-glucanase was tested on actively gro wing R. solani hyphae. beta-1,3-Glucanase induced morphological change s such as hyphal tip swelling, bursting, leakage of cytoplasm, and for mation of numerous septae.