Evaluation of the biocontrol ability of Pichia membranaefaciens yeast against Aspergillus tubingensis and Penicillium crustosum causing bunch rot disease in grapes

Bunch rot disease is one of the most important diseases of grapes caused by the storage rot fungi such as Aspergillus tubingensis and Penicillium crustosum. In this study, some biocontrol mechanisms of two Pichia membranaefaciens strains such as competitive potential, the siderophore and toxin production capacity, the interactions between yeast cells and fungal hyphae and also the ability of lytic enzymes production against fungal pathogens were investigated. The yeast strains showed higher competitive ability against the pathogens on PDA medium supplied with 4 g of dextrose. The yeast strains could inhibit the growth of the pathogens in dual culture test and also, had the siderophore and toxin production capacity. The results of the assay on the interactions between yeast cells and fungal hyphae demonstrated that yeast cells had a high capability of attaching to the pathogens hyphae. The ability of production of lytic enzymes was observed in yeast strains as well. In storage condition, P4 strain decreased the infection level A. tubingensis and P. crustosum in grapes by 49.16% and 62.64%respectively. This strain could also reduce the infection percentage by 44.88% and 50.3% respectively. The results of this study suggest the biocontrol ability of yeast strains against pathogens growth under both in vivo and in vitro conditions.