Primary characterization of bacteriocin paracin C – A novel bacteriocin produced by Lactobacillus paracasei

Lactobacillus paracasei CICC 20241 produces a 5 kDa bacteriocin, named paracin C, active against seventeen strains of Alicyclobacillus acidoterrestris used in this study. Paracin C was produced at high levels in MRS broth at 37 °C, reaching a maximum production of 1800 AU/ml using A. acidoterrestris DSM 3922 as target strain. The primary mode of action of paracin C is most probably due to pore formation, as indicated by the efflux of K+ from metabolically active cells of A. acidoterrestris. In the presence of 10 mM gadolinium, paracin C did not affect cells of A. acidoterrestris. This suggests that the mode of action of paracin C relies on a net negatively charged cell surface. In addition, effect of different medium components on paracin C production was studied.