Physiological and Antagonistic Properties of Pichia kluyveri for Curative and Preventive Treatments Against Post-Harvest Fruit Fungi

Postharvest fruit loss due to spoilage is mainly attributed to fungal infections. Synthetic chemicals can be used to preserve fruits, but they are expensive and pose risks to human health. The replacement of these chemicals by safer and cost-effective biocontrol agents is now a priority. This study investigated the physiological characteristics of Pichia kluyveri and its potential use as a biofungicide. The antagonistic effect of P. kluyveri against Botrytis cinerea and Monilinia laxa was tested on yeast peptone dextrose agar, grapes, apples, and pears. Yeast growth was variably possible at different temperatures, pH, and salinity levels. Strain-dependent antagonistic responses were observed on agar plates, where M. laxa was the more sensitive fungus to the antagonistic yeast. P. kluyveri demonstrated strong physiological properties under stressful temperature, pH, and salinity conditions. Preventive applications of P. kluyveri to apples were 95% effective against B. cinerea and 100% effective against M. laxa. Fruit type-dependent responses were evident on pears. Similarly, preventive application on grapes was also effective against the fungal pathogens studied. In general, the antagonistic responses were both fungus- and treatment- (curative and preventive) dependent. Therefore, the preventive use of P. kluyveri against post-harvest fruit-fungal infections proved to be an effective method for biological control of grapes, apples, and pears against fungal spoilage organisms Botrytis cinerea and Monilinia laxa.