Abstract
One strain of Lactobacillus, identified as Lactobacillus rhamnosus TCELL-1, was isolated from the human rectum biopsies in our laboratory. In this study, we tried to investigate the production of bacteriocin or bacteriocin-like inhibitory substance by TCELL-1. By using of deferred agar spot assay, we observed that TCELL-1 can inhibit food pathogens effectively and inhibit some lactobacilli test strains to a certain extent. But there is no obvious inhibition effect with regard to TCELL-1 neutralized supernatant when tested by agar well diffusion assay. We turned to use Bioscreen assay to evaluate inhibition effect of TCELL-1 supernatant. Compared with control, Enterobacter aerogenes showed obvious growth difference in TCELL-1 supernatant. According to the growth phenomenon of E. aerogenes, it was suitable to call “growth retardation” effect rather than “growth inhibition”. Addition of catalase demonstrated that hydrogen peroxide was not the cause of growth retardation. Serial dilution of TCELL-1 supernatant assay also proved that the growth retardation does not cause by phage and nutrient depletion. The growth-retardation factor was heat-stable, not sensitive to proteolytic enzyme and could be precipitated by ammonium sulfate, suggested that it may be a protein complex.