Avaliação de propriedades probióticas de cepas de lactobacillus isoladas de subprodutos do processamento de frutas.

Abstract

Probiotics are living microorganisms that when ingested in sufficient amounts provide health benefits. However, to be incorporated as functional foods in the diet, probiotics require detailed studies to prove their safety and benefits. Strains selected for use as probiotics cannot have pathogenic characteristics or transmit antibiotic resistance genes and must survive passage through the gastrointestinal tract and proliferate in the gut in order to ensure their functionality. This study was designed to evaluate the probiotic potential of Lactobacillus spp. strains isolated from fruit processing by-products. To assess the probiotic potential, survival tests at different pHs and different concentrations of bile salts, antagonism against pathogenic bacteria, sensitivity to antimicrobial agents and survivability to the gastrointestinal tract were performed. Strains were in general tolerant when exposed to acidic pH, some of which were tolerant to pH 3 for two to three hours. Tolerance to bile salts was also observed, and bacteria were able to tolerate 1% concentration for up to three hours. The results obtained about antagonism against pathogenic bacteria varied among tests used, in which all strains were able to form inhibition halos when the antagonistic activity was tested in the presence of lactobacilli cells, while supernatant of cells free from certain strains failed to inhibit Staphylococcus aureus and formed less significant halos compared to other strains tested. When submitted to conditions of gastrointestinal tract simulation, in general, they showed good viability, keeping high values throughout the test except for two strains that lost viability after 122 and 92 minutes of simulation, respectively. Most of the strains tested exhibited antimicrobial resistance, in particular to kanamycin, tetracycline and erythromycin. The results obtained in this study indicate that the strains tested have good viability and potential to be used as probiotics, but further studies should be conducted to certify the safety of such strains in order to incorporate them into foods.