The activities of pectic enzymes in extracts from sound apples and from apples rotted by different fungi are described. Sclerotinia fructigenaand Botrytis cinerea rots had little or no polygalacturonase or macerating enzyme activity, but Penicillium expansum rots were very active in these respects. Extracts from each of the rots had very high pectinesterase activity, and contained galacturonic acid. None of the rots had any cellulase activity. Each of the fungi produced polygalacturonase, macerating enzymes, and pectinesterase in liquid media. The effects of adding extracts of apples to these media are described. Filtrates from cultures of S. fructigena and P. expansum liberated galacturonic acid from apple fruit fibre which had been thoroughly extracted with cold water. The phenolic jsubstances present in healthy and rotted tisues were estimated. B. cinerea and S. fructigena rots contained very little, but P. expansum rots contained as much as healthy tissue which had been allowed to brown. An extract of healthy apple tissue reduced the activity of the polygalacturonase in a culture filtrate of S. fructigena. The substances responsible for this were tentatively identified as leuco-anthocyanins which had been changed to other compunds following the action of polyphenoloxidase. Thej significance of these results is discussed.
No takes yet. Share an insight, caveat, or question.
Cole et al. (1961) studied this question.