Antimicrobial compounds of Lactic Acid Bacteria and the Bacillus subtilis group members isolated from Vietnamese fermented foods
(2021)
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- Nowadays, the demand of consumers for adopting new natural agents to protect against food-borne diseases like campylobacteriosis, salmonellosis or listeriosis has triggered the search for new bio-preservatives. Vietnam is known for its wealth of safe traditional fermented foods based on spontaneous fermentation. Interestingly, these products have surprisingly long shelf life, up to several years. The present study aimed to get more inside into the bacterial diversity of traditional Vietnamese fermented foods and to develop bio-preservative agents from GRAS (Generally Recognized as Safe) bacteria, for the control of foodborne pathogens. The composition of the microflora in traditional Vietnamese fermented foods was first exam-ined using a metagenomic approach. This analysis showed that LAB (Lactic Acid Bacteria), especially Lactobacillus spp., were predominant in all samples. Besides, other GRAS strains, such as members of the Bacillus subtilis group, were found with a noticeable abundance in samples of fermented meat, vegetables and marine products. Then, the antibacterial compounds from LAB and members of the B. subtilis group were screened against a panel of foodborne pathogens and characterized for their potential applica-tions. This screening selected one Lactobacillus brevis and eight Bacillus velezensis strains for their broad range antibacterial activities. The antibacterial compound from L. brevis strain HQV07 isolated from thit chua displayed activities against various bacteria, including the Gram-positive Listeria innocua, Bacillus cereus, Staphylococcus aureus and the Gram-negative Escherichia coli, Salmonella enterica, Yersinia enterocolitica and Campylobacter jeu-jeni. This antibacterial compound has the molecular weight of ca. 2.5 kDa and was shown to be sensitive to proteolytic enzymes and stable at 72oC for 15 min. Besides, bacilysin, a non-ribosomal peptide, was found in all Bacillus velezensis strains by using Ultra High Perfor-mance Liquid Chromatography - Mass Spectrometry and contributed as a major player in the antagonistic activity against Gram-negative foodborne pathogens. In conclusion, this work has unraveled two promising biopreservation agents for potential applications in the food industry.
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Vu, H. Q. (2021). Antimicrobial compounds of Lactic Acid Bacteria and the Bacillus subtilis group members isolated from Vietnamese fermented foods. https://hdl.handle.net/2078.5/118576