Study of the dynamic of cultural microbiome of kiwifruit along postharvest storage for the selection of beneficial microorganisms

The aim is to investigate the evolution of the microbial community of kiwifruit during postharvest storage and the impact of eight different bacterial strains, possessing specific metabolic activity, on the fruit of A. chinensis var. chinensis quality parameters. Additionally, the fate and growth of bacterial strains were assessed when inoculated on kiwifruit and subjected to cold storage conditions. Fruits were sampled in a commercial orchard in Italy (Latina, LT, Italy) and analyzed at harvest for the cultural population of fungi and bacteria. Approximately 250 fungal, yeast, and 500 bacterial strains were identified. Fungal strains were dissected for their potential pathogenic activity on fruit. Bacterial strains were also characterized for their potential beneficial functions (e.g., IAA, production, acetoin, siderophore) and their ability to grow at low temperatures. Sampling was performed during the first two months of storage with the aim of identifying the fungal and bacterial species specifically selected by cold storage. Eight bacterial species were selected for postharvest treatments on fruit to assess their potential ability to prolong storage, reduce losses, or increase fruit quality. Different strains showed the potential to inhibit Botrytis cinerea growth. Furthermore, six strains were able to increase sugar content in fruit; however, the effect was related to an increase in softening, suggesting that these strains were inducing an earlier ripening. Interestingly, the inoculation generally increases storage breakdown, a chilling-related disorder, suggesting a possible microbial component of this physiological disorder