Preliminary probiotic ability of lactic acid bacteria isolated from several sources

Abstract

Regular consumption of probiotic bacteria results in health benefits. The objectives of this study were: firstly, to isolate lactic acid bacteria (LAB) from various sources and evaluate their ability to inhibit the growth of pathogenic bacteria, and secondly to preliminarily characterize their probiotic capacity together with 6 strains isolated from previous work. From this study, 34 strains were isolated from different sources on MRS agar, of which 16 were catalase and oxidase negative and Gram positive. These strains were evaluated for their ability to inhibit Salmonella sp. Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. All the strains showed antibacterial activity inhibited one or more pathogens. The IAMm4 strain stood out for inhibiting the four pathogens, in addition to obtaining the highest value of the inhibition diameter against S. aureus (25.37 mm). Similarly, strain TEJ10m3 exhibited a diameter of 24.37 mm against Salmonella sp. and the AGCm3 strain a diameter of 24.47 mm against E. coli. In addition to the 16 isolates, 6 isolates from a previous study were included to assess their ability to grow at pH 6.5, 3.0 and 2.5 and their susceptibility to antibiotics. The CM4.C2.2 and FM4.CI.2 strains managed to survive at pH 3.0 and the AGCm3 and QM2C1 strains managed to survive at pH 2.5. For none of the antibiotics used, resistance was observed in the total of the 25 strains evaluated. These results demonstrate that the strains can be used as potential probiotics. Complementary studies can help to clarify the probiotic nature, as well as the identity of the strains.