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In Vitro and In Vivo Production of Pectin Lyase by Penicillium expansum. D. H. Spalding, Research Plant Pathologist, Market Quality, ARS, USDA, 13601 Old Cutler Road, Miami, Florida 33158; A. A. Abdul-Baki, Research Plant Physiologist, Plant Industry Station, Beltsville, Maryland 20705. Phytopathology 63:231-235. Accepted for publication 2 August 1972. DOI: 10.1094/Phyto-63-231.

Pectin lyase was produced by Penicillium expansum in artificial media and in apple tissue. Pectin lyase production was greatest in a medium containing a pectin-polypectate mixture, less in media containing malic acid or citric acid, and absent in media containing glucose. Crude pectin lyase from apples rotted by P. expansum was purified by ammonium sulfate fractionation and column chromatography on Sephadex G-100 and diethylaminoethyl cellulose. The purified pectin lyase was free of pectin esterase, polygalacturonase, carboxymethyl-cellulase, phosphatidase, and proteinase activity, and caused maceration and death of potato tissue. Pectin lyase activity was maximum at pH 6.5 with 0.4% citrus pectin as substrate. Calcium, magnesium, and manganese ions stimulated pectin lyase activity, and ethylenediamine-tetraacetic acid inhibited enzymatic activity in vitro. Pectin lyase retained 60% of its original activity, carboxymethylcellulase retained over 80%, and polygalacturonase retained less than 5% after 10 min at 50 C.

Additional keywords: blue mold rot, pectin trans-eliminase, apples, enzyme purification, cellulase.