Active Excretion of Bile Acids in Lactobacillus reuteri CRL 1098 is Mediated by ATP

BUSTOS, A. Y.; RAYA, R.; FONT DE VALDEZ, G; TARANTO, M. P.

BIOTECHNOLOGY LETTERS

SPRINGER

Año: 2011 p. 2265 - 2269

0141-5492

BA are powerful detergents which disorganize the lipid bilayer structure of cellular membranes. Specific bile resistance mechanisms have been described in intestinal bacteria, being bile efflux, bile salt hydrolysis, and intrinsic architecture and composition of cell membrane the most prevalent. Lactobacillus (L.) reuteri, a lactic acid bacterium member of the intestinal microbiota currently used as probiotic, showed a significant degree of resistance to the toxic action of BA. In this work the presence of an active efflux ATP-dependent of conjugated (taurocholic) and free (cholic) BA in the CRL 1098 strain is reported. However, due the high pKa (5.5) of cholic acid compared with the conjugated specie, a significant fraction (between 35-50 % at pH 6.5 and 5.2, respectively) of free BA was also able to diffuse passively, even in the absence of ATP. To our knowledge, our results represent the first evidence of ATP as the energy source involved in the BA extrusion in L. reuteri.