Study of the inhibitory effect of Lactobacillus strains and lysozyme on growth of Clostridium spp. responsible for cheese late blowing defect

Three strains of Lactobacillus were  previously isolated from dairy products, Lactobacillus casei 26, Lactobacillus delbrueckii subsp. bulgaricus 76 and L. casei 95. Anti-costridial activities of these strains were evaluated against a collection of Clostridium isolates, belonging to species responsible for late blowing defect in cheese. The three strains of Lactobacillus inhibited the growth of all Clostridium isolates analyzed. The inhibitory effect of cell-free supernatant of each of these Lactobacillus strains combined with that of commercial strain L. casei BAL C, or with a solution of lysozyme, were compared by disc diffusion assay. Mixtures of cell-free Lactobacillus supernatants and lysozyme exhibited higher inhibitory activity than the supernatants and lysozyme solution separately (P < 0.05). Additionally, Lactobacillus strains were resistant to lysozyme concentrations usually used during cheese making process.