Preservative effects of a novel bacteriocin from Lactobacillus panis C-M2 combined with dielectric barrier discharged cold plasma (DBD-CP) on acquatic foods

In this study, a novel bacteriocin Lactocin C-M2 produced by Lactobacillus panis C-M2, combined with dielectric barrier discharged cold plasma (DBD-CP), was used to evaluate the antibacterial effect on aquatic foods. After the purification procedures of ethyl acetate extraction, cation exchange chromatography and semi-preparative liquid phase, the stability of Lactocin C-M2 under DBD-CP environment was determined, and the preservation effect of these two joint treatments was investigated on fresh white fish samples. As revealed by LC-MS/MS and BLAST analysis, Lactocin C-M2 is a new type of class II bacteriocin, with a molecular weight of 863.52 Da and the N-terminal sequence MVKKTSAV. Application of Lactocin C-M2 showed significantly stronger inhibitory effect on bacteria than on yeasts and mold. All the tested 10 Gram positive bacteria and 3 Gram-negative bacteria, including Staphylococcus aureus, Shigella flexneri, Bacillus spp, Lactobacillus spp, Escherichia coli, Pseudomonas aeruginosa, and so on, were inhibited. Lactocin C-M2 also presented stable antibacterial activity after exposure to DBD-CP, with the 95% residual activity against Staphylococcus aureus under the 40 similar to 80 kV voltage for 30 similar to 180 s, indicating the possibility of synergistic application. Combined with addition of 0.9 mg/g Lactocin C-M2, the treatment of DBD-CP with voltage at 60 kV for 90 s on fresh white fish (Culter alburnus) could significantly inhibit the microbial growth, the accumulation of volatile nitrogen and histamine during the storage. Therefore, the Lactocin C-M2, used together with the DBD-CP, is effective in food preservation.