Effects of Commercial Fatty Acids on Cutinase Release by Ascochyta pisi

Abstract

The effect of a range of commercially available C16 and C18 fatty acids, on the release of cutinase by Ascochyta pisi, was studied. When juniperic acid was used as sole carbon source, cutinase activity was released in the culture medium, and was markedly enhanced by post-treatment of A. pisi cultures with acetone used as enzyme extractor. Without acetone, less cutinase was naturally released in culture medium containing juniperic acid at 0.5 %, than at 0.0l % or 0.05 %. Upon post-treatment with acetone, the same level of cutinase was released with all three concentrations, thus suggesting that the enzyme was induced, but not completely released in the presence of 0.5 % juniperic acid. When ricinelaidic or ricinoleic acids were supplemented at 0.5 % to cutin in the culture medium, they strongly inhibited the release of cutinase, even with acetone post-treatment. Comparable inhibition by ricinoleic acid was also observed when juniperic acid was used as cutinase inducer, thus suggesting that not only the release, but also the production of cutinase were inhibited.