Optimization of cultivation strategy and medium for bacteriocin activity of Enterococcus faecium HDX-2

A lactic acid bacteria (LAB) isolated from pickled Chinese cucumber was screened for bacteriocin production. The strain was identified to be Enterococcus faecium HDX-2. Based on the Plackett-Burman (PB) experiment, glucose, Ca²⁺, and initial pH were found to be the most significant parameters of bacteriocin production. Afterward, effects of the three main parameters on bacteriocin activity were further investigated by central composite design (CCD) and the optimum composition was glucose 22 g/L, Ca²⁺ 0.6 mM, and initial pH 7.2. Optimum results showed that bacteriocin activity was increased to 1337.60 ± 36.71 AU/mL, 2.23-fold higher than in MRS medium without parameters optimization. The bacteriocin also showed significant antimicrobial activity against Listeria monocytogenes in meat and cheese model system.