PRODUCTION AND PURIFICATION OF A CHITINASE FROM EWINGELLA-AMERICANA, A RECENTLY DESCRIBED PATHOGEN OF THE MUSHROOM, AGARICUS-BISPORUS

The chitinolytic properties of Ewingella americana, a recently describ ed pathogen of the mushroom, Agaricus bisporus, are reported. E. ameri cana was shown to produce chitinolytic activity in the absence of chit in and in the presence of glucose and N-acetylglucosamine, indicating constitutive synthesis by these strains. A single 33-kDa protein with chitinolytic activity was purified to homogeneity from culture filtrat es, by hydrophobic interaction chromatography using a phenyl-group sub stituted matrix. This enzyme, by virtue of differential activity again st chromogenic chitooligosaccharides and against dye-labelled soluble carboxymethylated chitin (CM-chitin-RBV), was demonstrated to be an en dochitinase. Our data suggest this 33-kDa chitinase appeared to be the only chitinolytic enzyme produced by E. americana, strains of which d o not grow using chitin as a carbon source. The significance of these findings in the context of mushroom disease is discussed.