Dual Effects of Lactobacilli as a Cholesterol Assimilator and an Inhibitor of Gastrointestinal Pathogenic Bacteria

Abstract

Background: Probiotics are live microbial supplements which can improve the healthy intestinal microbial balance. Lactobacilli are a group of lactic acid producing bacteria (LAB) that are known as natural probiotics found in the dairy products. Objectives: In this study, we aimed to detect the most potent Lactobacillus isolates of the Fars province local dairy products in cholesterol removal and investigate their antibacterial properties against some gastrointestinal pathogens. Materials and Methods: Fifteen locally produced yogurt samples of the Fars province were collected and characterized with routine microbiology methods. Cholesterol removal ability of the Lactobacilli isolates were determined, and their growth inhibitory effect on some standard pathogenic strains pathogen was evaluated using the well-diffusion method. Results: In this study, five common strains of Lactobacilli including L. acidophilus, L. casei, L. fermentum, L. lactis, and L. bulgaricus were identified in the samples obtained from the locally produced yogurt in the Fars province. L. lactis and L. acidophilus were determined as the two most active strains with the maximum rate of cholesterol assimilation (5.6 and 4.5 mg/mL, respectively) in the process of cholesterol removal. In the antibacterial activity assay, the two mentioned strains had significant inhibitory effect on all of the tested bacteria except for B. subtilis. Conclusions: Cholesterol removal ability had a direct relation with bacterial growth, so it is suggested to use the probiotic bacteria in the growth phase to achieve better results.