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 described pathogen of the mushroom, Agaricus bisporus, are reported. E. americana was shown to produce chitinolytic activity in the absence of chitin 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 filtrates, by hydrophobic interaction chromatography using a phenyl-group substituted matrix. This enzyme, by virtue of differential activity against chromogenic chitooligosaccharides and against dye-labelled soluble carboxymethylated chitin (CM-chitin-RBV), was demonstrated to be an endochitinase. Our data suggest this 33-kDa chitinase appeared to be the only chitinolytic enzyme produced by E. americana, strains of which do not grow using chitin as a carbon source. The significance of these findings in the context of mushroom disease is discussed.