Metschnikowia pulcherrima, a new yeast with potential for biocontrol of postharvest fruit rots

Losses from postharvest pathogens on fruits and vegetables have been principally managed by synthetic fungicides. Consumer concerns about possible risks associated with the use of fungicides, along with development of pathogen resistance to certain fungicides have resulted in an intensive search for safer, more effective control options that pose minimal risk to human health and the environment. Significant progress has been made in developing potential biological alternatives to synthetic fungicides for the control of postharvest spoilage and toxin-producing fungi of fruits and vegetables. The use of microorganisms, particularly yeasts that occur naturally on the surface of fruits or vegetables, usually has been preferred for the control of postharvest diseases. Yeasts are suitable as biocontrol agents of postharvest diseases because they rapidly colonize and survive on fruit surfaces for long periods of time under different conditions, use available nutrients to proliferate rapidly, limit nutrient availability to the pathogen and generally are unaffected by fungicides used commercially. A new ascosporic yeast, Metschnikowia pulcherrima, that was isolated from grapes grown in Romania is described. Preliminary tests indicate the new species has biocontrol activity against Monilinia rot of stored apricot. M. pulcherrima reduced the incidence of fruit rot by 100% in a storehouse at 4 degrees C. The population density of M. pulcherrima was about 2 x 10(6) cfu/fruit.