Exploring the Biocontrol Capability of Non-Mycotoxigenic Strains of Penicillium expansum

is one the major postharvest pathogens of pome fruit during postharvest handling and storage. This fungus also produces patulin, which is a highly toxic mycotoxin that can contaminate infected fruits and their derived products and whose levels are regulated in many countries. In this study, we investigated the biocontrol potential of non-mycotoxigenic strains of against a mycotoxigenic strain. We analyzed the competitive behavior of two knockout mutants that were unable to produce patulin. The first mutant (∆ ) involved the deletion of the gene, which is the initial gene in patulin biosynthesis. The second mutant (∆ ) involved the deletion of , which is a global regulator of primary and secondary metabolism. At the phenotypic level, the ∆ mutant exhibited similar phenotypic characteristics to the wild-type strain. In contrast, the ∆ mutant displayed altered growth characteristics compared with the wild type, including reduced conidiation and abnormal conidiophores. Neither mutant produced patulin under the tested conditions. Under various stress conditions, the ∆ mutants exhibited reduced growth and conidiation when exposed to stressors, including cell membrane stress, oxidative stress, osmotic stress, and different pH values. However, no significant changes were observed in the ∆ mutant. In competitive growth experiments, the presence of non-mycotoxigenic strains reduced the population of the wild-type strain during in vitro growth. Furthermore, the addition of either of the non-mycotoxigenic strains resulted in a significant decrease in patulin levels. Overall, our results suggest the potential use of non-mycotoxigenic mutants, particularly ∆ mutants, as biocontrol agents to reduce patulin contamination in food and feed.