A new way to reduce postharvest loss of vegetables: Antibacterial products of vegetable fermentation and its controlling soft rot caused by Pectobacterium carotovorum

Abstract Bacterial soft rot caused by Pectobacterium carotovorum has brought huge economic losses to post-harvest vegetables. In this study, vegetables were used as raw materials to produce food-grade antibacterial products, fermented by lactic acid bacteria, to control P. carotovorum. A total of 32 kinds of vegetables were fermented by Lactobacillus paracasei WX322, results showed that 31 vegetable fermentation products had antibacterial activities at different levels. The green pepper fermentation antibacterial product (GPFA) had the highest activity and was selected for further analysis. On the 7th day of fermentation, the antibacterial activity of GPFA reached the maximum, with 640 AU/mL. Two bacteriocins, GP-19 and EP-20, were identified by LC-MS/MS. Growth curve and time-kill curve showed that the GPFA could effectively inhibit and kill P. carotovorum at a dose-dependent manner. SYTO9TM/PI staining observation further confirmed its bactericidal ability. Meanwhile, GPFA treatment led to irregular deformation of cells with rough surface observed using scanning electron microscopy (SEM). Moreover, in vivo assay showed that GPFA treatment significantly reduced the disease incidence and decay degree of pepper soft rot. In addition, GPFA treatment could prolong the shelf life of fresh-cut bell pepper. This study indicates that antibacterial products based on vegetable fermentation can provide a new method for the control of vegetable soft rot.