The antimicrobial properties and biogenic amine production of lactic acid bacteria isolated from various fermented food products

Lactic acid bacteria (LAB) have been isolated from fermented foodstuff and pre-identified using API 50 CHL and confirmed by polymerase chain reaction method to investigate the protective properties against important foodborne pathogens of their cell-free supernatants (CFS) and neutralized cell-free supernatants (NCFS). The antimicrobial activity of CFS and NCFS was determined using agar well diffusion assay. Biogenic amine production of LAB strains were also monitored in tyrosine decarboxylase broth (TDB). The highest and lowest histamine production were obtained by Pediococcus pentosaceus (155.66 mg/L) and Lactobacillus plantarum (5.96 mg/L), respectively. CFS obtained from LAB isolates showed better antimicrobial effects against pathogens than NCFS. The CFS and NCFS obtained from L. plantarum showed a high antimicrobial effect against S. Paratyphi A with inhibition zone diameter 22.5 and 16.5 mm, respectively. The CFS and NCFS of L. raffinolactis showed strong antibacterial activities against Listeria monocytogenes, with zone diameter 23.5 and 24.5 mm. Practical applications Antimicrobial activity of cell-free and neutralized cell-free supernatants obtained from LAB strains was evaluated. Biogenic amine production of LAB strains were also monitored in tyrosine decarboxylase broth. All LAB isolates had the capacity to produce biogenic amines. Cell-free supernatants obtained from LAB isolates showed better antimicrobial effect against pathogens than neutralized cell-free supernatants. Our results showed that cell-free supernatants can be used as a bio-protective agent in the food industry.