Biocontrol activity of Debaryomyces hansenii against blue mold on apple and pear during cold storage

To provide fruit throughout the whole year, maintain quality and reduce spoilage, apples and pears are stored at low temperature. However, the development of rots, caused mainly by Penicillium expansum, cannot be avoided. To prevent fruit losses, biological control has been proposed as a potential alternative. In this work, 16 psychrotrophic, non-pectinolytic Debaryomyces hansenii strains were evaluated in a bioassay for their potential biocontrol against P. expansum rots in apples and pears. Isolates with different degrees of biocontrol effectiveness were further investigated in vitro to elucidate mechanisms of antagonism that may have contributed to biocontrol. No correlation between any of the studied mechanisms and biocontrol activity could be established. One of the isolates, designated F9D, was selected due to its ability to reduce rot incidence in more than 95% in apples and 85% in pears. This strain could be a good candidate for the development of a yeast-based formulation to protect both types of fruit. An ISSR-PCR method was developed for typing the selected strain. This molecular marker could be a useful tool to follow the fate of the strain applied on fruit.