Screening and Identification of Thermophilic Lactic Acid Bacteria Producing Antibacterial Substances Determined by OMP Analysis

Abstract

A total of forty-six lactic acid bacteria (LAB) strains were screened for production of antibacterial substances, out of which two strains, JAK-CS7-1 and JAK-M1-3, displayed broad inhibition spectra against Gram-positive and Gram-negative pathogenic bacteria. Based on physiological, biochemical and molecular methods, these two bioactive thermophilic LAB strains were identified as Pediococcus acidilactici. The amounts of lactic and acetic acids produced by these two LAB strains were determined by HPLC method and then used for preparing the organic acid model system performance (OMP). Thus, comparative evaluation of the antibacterial activities of the culture supernatants (CS) and the corresponding OMP, consisting of equivalent acids concentration and similar pH like CS, revealed that the OMP displayed lower activities than the CS. It was found that the antibacterial activities of the CS were greater than the OMP by 50% that could be attributed to the presence of additional antibacterial metabolites in the CS. The results of this study suggested that these two strains of Pediococcus acidilactici appear to contain other bioactive substances in addition to lactic and acetic acids.