Unravelling the interaction between bile acids ad lactic acid bacteria

MORENO, CAREN; GOMEZ, JORGE; LEDESMA, ANA E.; TARANTO, MARÍA PÍA; BUSTOS, ANA Y.

Encuentro; LI Reunion Anual de la sociedad Argentina de Biofisica; 2023

Bile acids (BA) are biological detergents involved in the emulsification of dietary lipids butalso are the main regulators of the shape and composition of the gut microbiota. However,the interaction between BA and lactic acid bacteria at a molecular level is not yet wellunderstood. The aim of this work was to evaluate the effect of different BA on the growth,bacterial surface properties and macromolecules composition of a Lentilactobacillus (L.)parabuchneri CB12 strain. CB12 was grown in the presence of increasing concentrationsof glycocholic acid, taurocholic acid, glycodeoxycholic acid, taurodeoxycholic acid(TDCA), deoxycholic acid (DCA), and cholic acid (CA). Differences in BA effect wasobserved, with the strain being more sensitive to free BA, especially CA, and among theconjugated BA, greater inhibition was observed in glycoconjugated than intauroconjugated.In addition, the self-aggregation capacity of the strain was determined in the presence ofincreasing concentrations of BA. In all assays, a gradual increase in self-aggregation wasobserved with incubation time. CA did not affect the self-aggregation percentage whileTDCA and DCA increased the values with respect to the control without BA. With regard tothe zeta potential (ZP), with TDCA and CA at sub-lethal concentrations more negative ZPvalues were observed and at higher concentrations more positive values were recorded,with a concomitant decrease in viable bacteria. With DCA a gradual increase of ZP wasobserved at all concentrations. Finally, the effect of BA on the main membranecomponents was evaluated using Raman spectroscopy. Significant changes in proteins,lipids and DNA were observed as a consequence of their exposure to the different BA. Inconclusion, the interaction of BA against LAB is a multifactorial phenomenon, which mustbe taken into account for understood the microbiota metabolism and composition.