JURADO-GAMEZ, Henry    JARRIN-JARRIN, Verónica. Lactobacillus lactis GROWTH KINETICS AND DETERMINATION OF PROBIOTIC EFFECT ON PATHOGEN STRAINS. []. , 14, 2, pp.49-62. ISSN 1657-9550.  https://doi.org/10.17151/biosa.2015.14.2.5.

Introduction: Acid lactic bacteria have been studied for their ability to grow in harsh environments and generate antagonisms with other microorganisms. The present study sought to determine the kinetic parameters of growth of Lactobacillus lactis and its effect on Escherichia coli, Salmonella typhimurium, Clostridium perfringens and Staphylococcus aureus. Materials and Methods: The growth of the lactic strain was evaluated at concentrations of 0.5, 1 and 2% bile salts; 1 and 1.5% bile; three levels of pH (2.5, 4.5 and 7) and two temperatures (38 and 45ºC). Susceptibility of all strains to Dicloxacillin, Cefepime, Cephalothin, Ciprofloxacin, Gentamicin and Penicillin was also evaluated using Kirby-Bauer technique. Inhibition of L. lactis and its supernatant in E.coli, S. typhimurium, S. aureus and C. perfringens and the following parameters were determined and estimated: growth, pH, sugar consumption, acidity and protein consumption during the kinetic fermentation in MRS. Peptides present in the L. lactis supernatant through HPLC were determined. Results: Growth of 1.2x109 and 4.1x109 CFU/ml at 1.2% bile and 0.5% bile salt was obtained; 1.1x1011, 2.1x1010 and 1.0x1010 CFU/ml for 2.5, 4.5 and 7 pH respectively; and 1.7x1013 and 1.4x1013 CFU/ml for 45 and 38ºC. The lactic strain showed resistance to Cephalothin and Dicloxacilin; C. perfringens, to Penicillin and Dicloxacillin; S. typhimurium and E. coli to Cephalothin; and S. aureus, to Dicloxacillin. L. lactis inhibited E. coli and C. perfringens, and the supernatant included S. aureus. Conclusion: It is concluded that L. lactis present adequate growth in conditions in vitro and inhibited E. coli, C. perfringens and S. aureus but not S. typhimurium.

: probiotic; growth; microbial antagonism; pathogenic bacteria; Lactobacillus lactis.

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