Inducible chitinolytic system of Aspergihs fumiga

Department of Microbiology, University of Leeds, Leeds LS2 9JT, UK Incubation of Aspergillus fumigatus NCPF 2140 in growth medium containing 1 O/ O chitin as sole carbon source led to induction of specific extracellular chitinolytic activity of 1-5 pmol GlcNAc released min'l (mg protein)'l. The effect was repressed by the inclusion of GlcNAc in the medium, indicating regulation by a negative feedback mechanism. Extracellular chitinase activity was inhibited by allosamidin (lCs0 0.12 pM). Multiple chitinolytic enzymes were detected on zymograms of extracellular preparations; levels of individual enzymes induced were dependent upon whether cells were incubated with purified colloidal chitin or a crude preparation of crystalline chitin. A major, inducible, 45 kDa chitinase was purified using ammonium sulphate precipitation, chitin affinity chromatography and a novel procedure involving the electroelution of the enzyme from a substrate gel containing glycol chitin. The enzyme is a glycoprotein with endochitinase activity.