Hydrolytic enzymes detected in the exudates of Ceratocystis paradoxa infected pineapple fruit

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AbstractExtracellularly expressed exudates from pineapple fruit infected by Ceratocystis paradoxa were partially purified and the exudate‐filtrate preparations were assayed for the presence of three hydrolytic enzymes. The preparations were found to contain cellulolytic and proteolytic enzymes when inoculated on carboxymethylcellulose and casein as substrates, respectively, while pectin‐methylesterases and polygalacturonases were detected in the exudate‐filtrate when apple pectin and sodium pectate were used as substrates, respectively. The activities and stabilities of these groups of enzymes were found to be optimal at pH 7.0 and at 30 °C. The exudates also exhibited macerating action when potato discs showed complete loss of coherence and maceration after a 24 hr incubation. More total reducing sugars were detected in exudates of infected fruit than those obtained from healthy fruit.