Phenolase Inhibitor from Cultures of Penicillium expansum which may Play a Part in Fruit Rotting

Abstract

PREVIOUS work in this laboratory¹ has shown that the light colour of apples infected with Penicillium expansum (“blue-mould”) is due to the inhibition by the fungus of the fruit's normal enzymatic browning system. A positive feedback system operates whereby the fungal pectolytic enzymes modify the apple's phenolics to yield inhibitors of apple phenolase (o-diphenol oxidase) and the associated biochemical defence system. But the problems of the initial establishment of fungal growth remain and I wish to report evidence that the fungus secretes its own phenolase inhibitor until it is sufficiently established to allow the second, major positive feedback system to take over.