Inhibitory effect and mechanism of curcumin-based photodynamic inactivation on patulin secretion by Penicillium expansum

Patulin (PAT) contamination caused by Penicillium expansum growth in postharvest fruit brings safety problems. This study investigated the inhibitory effect and mechanism of curcumin (CUR)-based photodynamic inactivation (PDI) on PAT secreted by P. expansum in vitro using a multifunctional light source instrument. After being treated with photosensitive CUR, the growth of mycelium was completely inhibited on potato dextrose agar medium, and the maximum PAT reduction of 93.06% can be achieved (330.0 J/cm², 300 μM CUR) in liquid medium. The inherent mechanism was that PDI causes the reactive oxygen species accumulation in cells, which destroyed the antioxidant defense system and induced severe oxidative damage, resulting in the loss of cell integrity. Furthermore, mycelial apoptosis caused up-regulation of five genes, including PatB, PatE, PatG, PatI, and PatL, but down-regulated ten genes in the PAT biosynthetic pathway. These findings suggest that CUR-based PDI can inhibit fungal infection and toxin secretion.Industrial relevanceThis study found that photosensitized curcumin can significantly inhibit mycelial growth and the secretion of patulin by Penicillium expansum. Curcumin-based photodynamic inactivation has the feasibility of the application on fresh fruits and vegetables, such as apples or oranges, and can avoided excessive waste of resources in picking, transporting, storing, and selling.