Bioactive compound and chemical characterization of lactic acid bacteria from fermented food as bio-preservative agents to control food-borne pathogens

Abstract

Context: Lactic acid bacteria (LAB), which are found in many fermented foods, are known to produce antimicrobial compounds that play a vital role in food bio-preservation. Aims: To screen, identify, characterize, and determine the secondary metabolites of LAB isolated from Thai fermented foods that are beneficial against Escherichia coli and Staphylococcus aureus. Methods: The antimicrobial activity of cell free supernatant (CFS) was evaluated by agar well diffusion assay, and determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC). Bacterial strains were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and chemical compound was conducted by gas chromatography and mass spectrometry (GC-MS). Additionally, microbial dynamic and bile salt tolerance were assessed. Results: Seven of the 90 lactic acid isolates from Thai fermented foods, showed antibacterial activity against E. coli and S. aureus in the 12.00–16.00 mm inhibitory zone. It was identified that the bacteria were Lactobacillus pentosus, Lactobacillus farciminis, Lactobacillus brevis, and Lactobacillus plantarum. The best antibacterial activity was represented by LBST1861 strain, which also provided bile salt resistance at 0.3% for 24 hours and had MIC and MBC values of 12.5 mg/mL and 50.0 mg/mL against S. aureus and E. coli, respectively. Furthermore, the GC-MS discovered a total of 16 chemical compounds that may be used to limit microbial growth and has a potential to be employed as a bio-preservative. Conclusions: The most potent strain of LBST1861 strain against S. aureus and E. coli as L. plantarum, isolated from fermented foods in Thailand, generated significant bioactive chemicals that can be applied to promote food products.