On the way to the technological development of new selected non-Saccharomyces yeasts as innovative biocontrol agents in table grapes

Post-harvest decay of fresh table grapes causes considerable annual production losses. The main fungal agents of decay both in pre- and post-harvest are Botrytis cinerea, Penicillium spp, Aspergillus spp, Alternaria spp and Cladosporium spp. At the time, the use of agrochemicals and SO2 are the main methods to control grape molds in pre- and postharvest, respectively. Significant improvements have been made in applying innovative more environmentally sustainable strategies, such as Biological Control Agents, BCAs, which can reduce disease severity in both pre- and post-harvest. In this study, 31 new non-Saccharomyces yeasts, isolated from berries of native Apulian grape vineyards, were tested for their in vivo effectiveness against grey mold of table grape and among them two St. bacillaris (N22_I1 and S13_I3), one S. diversa (N22_I3), one A. pullulans (OLB_9.1_VL) and one H. uvarum (OLB_9.1_BR) yeast strains were selected as efficient and good BCAs. Their mechanisms of action were characterized through in vitro assays, and additional characteristics were evaluated to assess economically feasible and viable for future technological employment. In detail, we tested their effectiveness reducing the working concentration, their antagonistic effect on a wide range of fungal pathogens, their ability to survive in formulations with long shelf life and their safety for human health.