Elma ve limonda bozulma etmeni olan fungal patojenlerinantagonistik mayalar ile biyokontrolü

In the present study, the biocontrol potential of epiphytic yeasts against two significant postharvest pathogens, Penicillium expansum DSM62841 (blue mold) and Penicillium digitatum DSM2750 (green mold) was evaluated in vitro and in vivo. „Starking Delicious‟ and „Kutdiken‟ cultivars were selected as the apple and lemon varieties, respectively. A total of 69 yeasts isolated from different cultivars of apples and lemons were identified by a combination of PCR-RFLP of the 5.8 S rRNA region and sequencing of the D1/D2 domain of the 26 S rRNA gene. After preliminary screening, Aureobasidium pullulans GE17 and Meyerozyma guilliermondii KL emerged as promising antagonistic strains due to their strong antagonistic activity against blue and green molds. Besides the experimentation with single and mixed cultures of these yeasts, the effects of different concentrations of the yeasts on biocontrol activity were also investigated. It was discovered that the antagonistic effect of these two yeast strains depends on several mechanisms of action, including competition for space and nutrients, production of VOCs, secretion of extracellular lytic enzymes (β-1,3 glucanase, protease and gelatinase), and inhibition of fungal spore germination. Using antagonistic yeasts, percent (%) inhibition of the mycelial growth of Penicillium expansum DSM62841 and Penicillium digitatum DSM2750 in vitro was achieved by 83.40% and 74.70%, respectively. Apples and lemons were stored in a cold room under industrial conditions for 3 months, and infection rate, disease severity, and lesion diameter of pathogens decreased by yeast treatment compared to the control throughout the storage period. In addition, yeast coated apples and lemons were stored at ambient condition (20 ± 2 °C and 50 ± 5 % RH) for 45 days, and results indicate that yeast application showed positive impact on the quality parameters including pH, titratable acidity, weight loss, brix, texture, and browning during storage. Biodegradation of patulin was achieved successfully by both of the studied yeasts and their mixed culture in vitro.