Cold-Adapted Yeasts as Biocontrol Agents: Biodiversity, Adaptation Strategies and Biocontrol Potential

Abstract

After harvest, many fruits are kept in cold storage in order to prolongtheir availability and shelf life. Often, this requires the application of a chemicalfungicide to prevent postharvest decay from decay fungi. An alternative approachfor preventing postharvest fungal decay during storage could be based on thetreatment of the commodity with antagonistic yeasts. In this regard, the use ofcold-adapted yeasts may offer a distinct advantage. Numerous cold-adapted yeastspecies have been isolated from artificial cold environments, as well as cold-storedfruits. Since the method employed to isolate potential antagonists has a majorimpact on the type and properties of the antagonist to be identified, it is importantto evaluate the consequences of the methods that are presently being utilized andto appraise whether or not they can be improved. Although the mechanism(s) bywhich yeast antagonists suppress postharvest diseases can be quite variable,competition for nutrients and space plays a major role in their antagonistic activity.Additionally, production of antibiotics, direct parasitism and the induction ofresistance in the harvested commodity are other modes of action that have beendocumented and suggested to play a role in how yeasts suppress postharvestpathogens in harvested fruits. While a few yeast-based products have been on themarket, this field of study is still in its infancy and it is likely that several new products will enter the market in near future. Nonetheless, it is necessary to continue to identify new potential microorganisms and to develop a better understanding of the biology of yeast biocontrol systems by involving yeasts, pathogens and host commodity, in order to increase the potential of postharvest biocontrol as a viable alternative to synthetic postharvest fungicides. While the results of this technology are encouraging, we need to continue to explore the potential use of appropriate yeasts worldwide where management practices, types of fruit and decay pathogens can vary considerably.