Resumo

The probiotic microorganisms have been used in various types of food products and its technological application in fermented dairy products aims to combine the potential health benefits of the bacteria with their ability to grow in milk, resulting in a nutritionally healthy and desirable product for the consumers. The aim of this study was to characterize the probiotic potential of LAB18s, isolated from “Minas Frescal” cheese and identified as Enterocuccus durans, through acid and bile salts resistance, survival in simulated gastrointestinal tract and hemolytic activity. The resistance of isolated under acid conditions it was realized at pH values: 2.0, 3.0, 4.0 and 7.0. Viable cell counts were determined after exposure to acidic condition for 0, 1, 2, 3 and 4 h at 37ºC. The resistance to bile salts was performed in 10 mL of sterile Brain Heart Infusion (BHI) medium supplemented with a mixture of sodium cholate and sodium deoxychotale in a ratio of 1:1, achieving final concentrations of 0.1, 0.25, 0.5, 1.0 and 1.5% (w/v). Total viable counts were determined after exposure to bile salt at 0, 1, 2, 3 and 4 h of incubation, in pour plate method with Brain Heart Agar (BHA) after serially diluting the sample and incubated at 37ºC for 24 h. Survival in simulated gastrointestinal tract was performed with 0.2 mL aliquot of bacterial suspension inoculated into 1.0 mL of simulated gastric or intestinal juices and incubated at 37ºC for 4 h. The hemolytic activity was performed using blood agar (7% v/v sheep blood) for 48 h incubation at 37°C. Strains that produced green-hued zones around the colonies (α-hemolysis) or did not produce any effect on the blood plates (γ-hemolysis) are considered non hemolytic. Strains displaying blood lyses zones around the colonies are classified as hemolytic (β-hemolysis). It was observed in this study that E. durans LAB18s showed resistance to acid conditions, except for pH 2; and it was able to survive in the presence of simulated gastric juice at pH 3, while at pH 2 it was observed viability of cells only at initial time (0 h); it demonstrated also survival capability in the presence of simulated intestinal juice with or without bile salts; and did not show hemolytic activity. In summary, the E. durans LAB18s showed potential health benefit and possibly could be used as promising probiotic strain in the food or feed animal industry.