The utilization of constituents of an apple fruit as a growth substrate, the production of polysaccharide-hydrolases, and the degradation of fruit tissue by the enzymes were examined with three strains of Penicillium expansum (O-385-10, MR-213-3, and IFO8800) P. expansum grew well on an agar plate containing xylan or pectin as a carbon source, and abundantly produced conidiospores. On the other hand, the organism showed poor growth on glucose, fructose or sucrose, and the production of spores was repressed by these saccharides. Cellulose and starch did not support the growth of the organisms. Crude enzymes (xylanase and pectinase) were prepared from the culture broths of the organism grown in the xylan and pectin liquid media, respectively. When the small cubes of an apple fruit were incubated with the crude enzymes, these enzymes released a large amount of reducing sugars from the cubes. It was observed that the xylanase degraded cell walls of the fruit and the pectinase separated cells from the fruit cubes .