Screening of bacteriocin-producing lactic acid bacteria in Chinese homemade pickle and dry-cured meat, and bacteriocin identification by genome sequencing

The control of foodborne pathogens in raw/processed foods is urgently needed. Lactic acid bacteria (LAB) bacteriocins are promising natural food preservatives. In this study, 81 antibacterial LAB strains were isolated from pickles and dry-cured meats, among which 38 LAB isolates inhibited both Staphylococcus aureus and Escherichia coli. Broad antibacterial LAB strains consisted of Lactobacillus, Pediococcus, Staphylococcus, and Weissella after identification according to 16S rDNA sequences. Antimicrobial activity of crude bacteriocins of the 38 strains was tested against multiple foodborne pathogens and L. pentosus DZ35 was selected to investigate further. L. pentosus DZ35 started to produce bacteriocin at 36 h during fermentation. The bacteriocin of L. pentosus DZ35 had good thermostability and broad pH adaption ranging from pH 2 to pH 11. Its antibacterial activity was partially lost after treated by proteinases. Genome of L. pentosus DZ35 was sequenced using Illumina sequencing and MinION nanopore sequencing platform with a size of 3,962,622 bp, including nine circular plasmids. Two novel bacteriocins, pentocin DZ1 and pentocin DZ2, were identified using BAGEL4. The present study indicates that pickle has abundant bacteriocin-producing LAB and the probiotic L. pentosus DZ35 has promising potentials to control pathogens in food.