Investigation of the usage potential of yeasts isolated from different environments as a biocontrol agent

The control of Penicillium expansum pathogenic mold causing blue mold spoilage on apple is an important problem for apple is fruit industry. For this reason, the application of antagonist yeasts, which is an alternative method, is recommended to be used as biocontrol agents in order to reduce the use of fungicides and to minimize economic losses. In this study, yeast strains with high antagonist properties were selected from Cryptococcus albidus strains isolated from different fruits. 4 7 and 9 log cfu/g of the selected yeast strain were inoculated into approximately 3 mm diameter holes drilled on the apple and P.expansum mold (4 log cfu/g) was inoculated after 10 minutes. Apples were stored in sterile containers at 4, 10, 15 and 25 ° C with 85% and 95% relative humidity and yeast and mold were counted every 7 days. The diameter of rot formed around the drilled holes was measured on the 40th day of storage. According to the results of the total yeast mold analysis performed at the end of the storage, it was seen that the amount of mold decreased as the temperature and humidity increased. For example, while the amount of mold in apples without yeast culture was increased up to 8,86 log_10⁡〖cfu/g〗, it reached 6.95 log cfu/g mold at the highest yeast dose. While these values are observed in the lowest temperature storage conditions, mold growth is suppressed as the temperature increases. Considering the applied parameters, it is seen that storage time-storage temperature and storage time-yeast amount are effective together in mold inhibition (p<0,05). The interaction of storage temperature, humidity and storage time also has an inhibition effect on mold growth (p<0.05). In our study, the diameter of spoilage decreased to 0.5 - 0.7 cm in 7 and 9 log cfu/g yeast cultured apples compared to the apples without yeast culture. The ideal temperature, which showed a decrease in the count of P.expansum and the diameter of rot, was observed in the presence of 7-9 log cfu/g yeast concentration at 95% humidity at 4-15 °C. According to the analysis results, it was determined that the selected yeast strain had an antagonistic effect on P.expansum mold in the determined parameters in vivo and in vitro conditions. Keywords: Antagonistic yeast, biocontrol, apple