Transformation of Inferior Tomato into Preservative: Fermentation by Multi-Bacteriocin Producing Lactobacillus paracasei WX322

Loss and waste of postharvest vegetables are the main challenges facing the world's vegetable supply. In this study, an innovative method of value-added transformation was provided: production of bacteriocin from vegetable waste, and then its application to preservation of vegetables. Antibacterial activity to soft rot pathogen Pectobacterium cartovorum (Pcb BZA12) indicated that tomato performed best in the nutrition supply for bacteriocin production among 12 tested vegetables. Moreover, the antibacterial activity was from Lactobacillus paracasei WX322, not components of vegetables. During a fermentation period of 10 days in tomato juice, L. paracasei WX322 grew well and antibacterial activity reached the maximum on the tenth day. Thermostability and proteinase sensitivity of the bacteriocin from tomato juice were the same with that from Man-Rogosa-Sharpe broth. Scanning electron microscope images indicated that the bacteriocin from tomato juice caused great damage to Pcb BZA12. At the same time, the bacteriocin from tomato juice significantly reduced the rotten rate of Chinese cabbage from 100% +/- 0% to 20% +/- 8.16% on the third day during storage. The rotten rate decrease of cucumber, tomato, and green bean was 100% +/- 0% to 0% +/- 0%, 70% +/- 14.14% to 13.33% +/- 9.43%, and 76.67% +/- 4.71% to 26.67% +/- 4.71%, respectively. Bacteriocin treatment did not reduce the rotten rate of balsam pear, but alleviated its symptoms.

Automated summary

This study innovatively used vegetable waste to produce bacteriocin, which significantly improved the preservation of vegetables, with tomato providing the best nutrition supply. The bacteriocin showed strong antibacterial activity against soft rot pathogens, reducing the rotten rate of various vegetables during storage.