BILE ACIDS MODIFY MORPHOLOGY OF A POTENTIAL PROBIOTIC LACTIC ACID BACTERIUM

MORENO, CAREN N.; GÓMEZ, JORGE N; LEDESMA, ANA E; TARANTO, MARIA P; BUSTOS, ANA Y

San Miguel de Tucumán

Simposio; VI International Symposium on Lactic Acid Bacteria - I Argentinean-Japanese Lactic Acid Bacteria "Tohoku Forum for Creativity" Meeting; 2024

Centro de Referencia para Lactobacilos

Bile acids (BAs) are the main endogenous modulators of the composition and metabolic activity of the intestinal microbiota. In the present work, the effect of conjugated [taurodeoxycholic (TDCA)] and free [cholic acid (CA) and deoxycholic acid (DCA)] BAs, on the survival, structural and surface properties of Lentilactobacillus (L.) parabuchneri CB12 was evaluated applying viability assays, and Scanning Electron Microscopy (SEM). Our results evidenced that free BAs were more toxic than conjugated, with CA being significantly more harmful than DCA). SEM showed that untreated bacterial cells exhibit well-defined morphology characteristic with short rod shape and a smooth surface. No bacterial aggregates were observed. With TDCA addition, the cell surface appeared rougher and irregular with some depressions. Granular precipitate corresponding to the DCA released by the action of the CB12-bile salt hydrolase enzyme was observed. Treatment with free BAs such as DCA and CA caused a significant changes at lower concentrations. Thus, bacterial cells treated with 2 mM DCA and 0.05 mM CA showed significant surface distortions and many bacteria presented depressions and fold formation on the surface. In general, cells were longer than control cells and interrupted septa as signal of incomplete cell division were also observed. SEM micrographs showed bacterial aggregates, which would be related to modifications in their surface properties by exposure to BAs. Remarkably, exposure to CA revealed pore-like depressions. In general, the magnitude of the effects founded was dependent to the type of BA and its concentration, being more evident in the presence of CA even at low concentrations, which would explain its greater inhibitory effect. This work provides useful information about the effects of BAs on lactic acid bacteria strains and it would allow the development of strategies to positively modulate the composition of the microbiota.