IN-VITRO ASSESSMENT OF BILE SALT HYDROLASE ACTIVITY, BILE SALT RESISTANCE, SURFACE AND ADHESIVE PROPERTIES OF LACTIC ACID BACTERIA

SESÍN, ABRAHAM A.; LEDESMA, ANA E.; TARANTO, MARÍA PÍA; BUSTOS, ANA Y.

Congreso; XVII Congreso Argentino de Microbiología General; 2022

For several years, the literature has described innumerable benefits attributed to probiotic bacteria;including the reduction of serum cholesterol levels. This effect is often associated with the microbial bile salt hydrolase (BSH) enzyme. Cell surface characteristics that allow bacterial adhesion to the intestinal mucosa is another major selection criterion for a potentially successful probiotic. This would allow colonization of the colonic mucosal surfaces, at least transiently, thus interfering with pathogen binding, allowing interaction with immune cells and exert their benefits. The present research focused on the probiotic characterization of seventeen lactic acid bacteria isolated from artisanal goat's cheese based on their absence of hemolytic activity, low pH (2.5) tolerance, bile-salt resistance [5 mM taurodeoxycholic acid (TDCA) and deoxycholic (DCA)], BSH activity, hydrophobicity, auto-aggregation, and mucus adherence. The outcome of these studied parameters was used as input data for a principal component analysis (PCA) to select the most promising isolates that were identified through 16S rDNA sequencing. None of the tested strains showed hemolytic ability, while all strains showed high survival (more than 76 % at 1.5 h and 3 h) to low pH. In addition, 16 of the 17 strains exhibited survival rates above 75 % in the presence of TDCA. In contrast, in the presence of DCA, only three strains achieved survival rates of 75%, while the remaining strains had values ranging from 32 to 73%.Hydrophobicity and auto-aggregation values varied between LAB with ranges between 15.5±1.8 to 84.7±3.2, and 4.72 to 59.2%, respectively. All selected LAB were capable of adhering to intestinal mucus in a range of1.2x105 to 8x106 UFC/mL. Remarkably, eight strains showed high BSH activity. According to the PCA, the best performance was achieved by CB1, 8, 10 and 12 strains, that were identified asLentilactobacillus parabuchneri (CB1 and CB12) and Lactiplantibacillus plantarum (CB8 and CB10). Our results contribute to the probiotic characterization of new LAB strains that is of interest both toacademic institutions as well as to respond to the current demand for novel functional foods.