Bacillus vallismortis Bioextracts Combined with Cold Plasma Air for Post-Harvest Fungi Biocontrol in Tomato (Lycopersicum solanum)

Post-harvest diseases caused by phytopathogenic microorganisms generate significant economic losses, particularly in tomato crops affected by Alternaria solani. This study evaluated the effectiveness of cold plasma combined with a bioextract of Bacillus vallismortis as a biological strategy to extend tomato shelf life. In vitro antagonism assays were performed by confronting B. vallismortis against A. solani. Additionally, shelf-life tests were conducted on tomatoes treated with Bacillus cells and Bacillus cell-free bioextract (BCFB), followed by inoculation with A. solani spores, assessing incidence, severity, weight loss, and microbiological parameters over time. Subsequently, tomatoes were treated with cold plasma in combination with BCFB and reevaluated. Results showed significant antagonistic activity, with B. vallismortis and BCFB inhibiting A. solani by 75% and 50%, respectively. In untreated tomatoes, BCFB reduced disease incidence to 66.66% and severity to scale 2, compared to 100% incidence and scale 5 severity in controls. The combined treatment with cold plasma and BCFB showed the highest effectiveness, completely inhibiting A. solani (0% incidence, scale 0 severity), with tomatoes remaining healthy after 25 days. These findings demonstrate that cold plasma combined with B. vallismortis represents an effective and sustainable alternative for controlling post-harvest phytopathogens and extending tomato shelf life.