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This study evaluated the antibacterial activity of bacteriocin produced by Bacillusstrains against biogenic amines (BA)-forming lactic acid bacteria (LAB), and the applicability of desirable strains as Bacillusstarters for safety and quality improvement of fermented soybean products. The BA-forming ability of the tested LAB in amino acid decarboxylase broth was mostly strain specific rather that species specific. The bacteriocin produced by specific Bacillusstrains: Bacillussp. DB407, Bacillus licheniformisDB612, and Bacillus subtilisDB821 may play a contributory role in the inhibiting the growth of BA-forming strains. In fermented soybean products manufactured using different starter cultures, there was a significant reduction (p< 0.05) in the cell counts of LAB by application of a mixed culture containing B. subtilisDB821, which showed the highest antimicrobial activity. Specifically, B. subtilisDB821 was highly efficient in reducing accumulation of cadaverine, tryptamine, and tyramine produced by Enterococcus faeciumD12 and Enterococcus faecalisD51 during soybean fermentation. In conclusion, the bacteriocin-producing Bacillusstrains such as Bacillussp. DB 407, B. licheniformisDB612, and B. subtilisDB821 can be used as a starter culture for the production of BA-controlled soybean products and for the enhancement of the quality and safety of fermented foods.

The aim of this study was to investigate the antimicrobial effects of purified bacteriocins isolated from Lactobacillus brevisBK11 and Enterococcus faecalisBK61 on Helicobacter pylori. After the final purification step, the molecular weights of the purified bacteriocins from L. brevisBK11 and E. faecalisBK61 were estimated to be approximately 6.5 and 4.5 kDa, respectively. Significant decrease in the antimicrobial activity of these bacteriocins was observed when they were treated with several proteolytic enzymes. However, their antimicrobial activity was stable over long periods of storage and a wide range of pH and was relatively heat resistant. The inhibitory spectrum of the bacteriocin produced by L. brevisBK11 strain was quite narrow, whereas the bacteriocin produced from E. faecalisBK61 strain exhibited a broad antimicrobial spectrum against various foodborne pathogens such as Listeria monocytogenes, Escherichia coliO157, and Salmonella enteritidis. Treatment of H. pyloriwith these bacteriocins significantly reduced the number of cells of the pathogen found adhering to the monolayers of cultured human gastric adenocarcinoma epithelial cell line (p< 0.05). Furthermore, the urease activity of adherent H. pyloriafter treatment with the bacteriocins was lower than that for the control group, but there appeared to be no significant difference between the competition and displacement groups (p> 0.05).