Studies on the acetylesterase of Sclerotinia laxa

Abstract

The presence of an acetylesterase of Sclerotinia laxa was demonstrated. The activity of the enzyme towards phenolic esters of fatty acids decreased with increasing molecular weight of the side chain, and was also related to the nature of the phenolic nucleus. The esterase showed optimum activity at pH 7.8, and was relatively resistant to inhibition by diethyl p-nitrophenyl phosphate. Exocellular enzyme activity of developing cultures of S. laxa in a liquid medium lagged behind mycelial growth, but localized production was demonstrated at an early stage in cultures on solid medium. On the basis of these results, the enzyme appears akin to type A serum esterases. From crude extract of S. laxa 4 components with esterase activity were separated by paper chromatography. Exocellular fungal esterase appears to play a large part in bringing about the fungistatic activity of phenolic esters.