Microbial biocontrol strategies for sustainable food processes

The doctoral thesis mainly focused on the use of Lactic Acid Bacteria (LAB) as biocontrol agent for maintaining the quality of agri-food products, on ready-to-eat fruits. A polyphasic characterization of the LAB strains selected for biocontrol was performed, by focusing also on probiotic and functional properties which they could give to ready-to-eat fruits. This thesis is structured in three parts: introduction (Chapter 1), experimental section (Chapters from 2 to 7) and conclusions (Chapter 8). The experimental section is subdivided into two sub-sections. The first experimental section consists in two chapters (Chapters 2 and 3) in which the methods for antifungal characterization and application of LAB metabolites (CFSs) in sliced kiwifruits (Chapter 2) and for isolation, antifungal and probiotic characterization and application of living cell (LAB suspension) in table grapes berries (Chapter 3) were preliminarily tested with LAB strains belonging to UNIFG microbial culture collection and coming from ecological niche (such as sourdough and honey, respectively) different to those of the final application (e.g. fruit surface and tissue, such as sliced kiwifruit and table grapes berries). The second experimental section, and the core of this work, consists in four chapters (Chapters from 4 to 7), in which the methods tested above were employed and new techniques and applications were developed from them, with the common thread that the same LAB strains were utilized during the whole section and that the LAB used in this case derived from ecological niches like those in which they were applied (e.g. fruit surface). In particular, these 5 LAB strains were isolated from the surface and tissues of wild fruits and vegetables and characterized for their probiotic activity (Chapter 4), subjected to an extensive metabolites profiling and characterization of antifungal activity (Chapter 5), and finally applied as LAB strains with dual functionality on table grapes berries (Chapter 6) and strawberries (Chapter 7), with different methods of application.