Characterization of an anti-Listeria bacteriocin produced by Lactobacillus plantarum LB-B1 isolated from koumiss, a traditionally fermented dairy product from China

Lactobacillus plantarum LB-B1, isolated from a traditionally fermented dairy product koumiss, produced a bacteriocin active against strains of Listeria, Lactobacillus, Streptococcus, Enterococcus, Pediococcus and Escherichia. Pediocin LB-B1 was sensitive to proteolytic enzymes, but stable between pH 2.0–10.0 and heat resistant (15 min at 121 °C). It did not adhere to the surface of the producer cells. However, adsorption to both resistant and sensitive cells was observed. Production of the bacteriocin started at the early exponential phase and reached its maximum at the early stationary phase. This result suggested that pediocin LB-B1 was produced as a primary metabolite. Its mode of action was bactericidal, as determined against Listeria monocytogenes 54002. Pediocin LB-B1 was estimated between 2.5 kDa and 6.5 kDa by tricine–SDS–PAGE. Furthermore, the gene cluster encoding pediocin LB-B1 showed 99.8% homology with the operon encoding pediocin PA-1, suggesting that the two bacteriocins are identical.