Raman spectroscopy a powerful tool to evaluate the action of bile acids on strains of lactic acid bacteria

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

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

Raman spectroscopy is a powerful and costeffective method that has emerged in recentyears for profiling the intracellular molecular composition (such as DNA, RNA, proteins,and lipids) of single cells. The molecules in the sample, interact with the excited light of amonochromatic laser and it generate vibrations of the molecular bonds. Thus, Ramananalysis provide rich biomolecular information, including the spectral vibrationinformation of the biological bonds of nucleic acids, proteins, carbohydrates, and lipids.Bile acids (BA) are biological detergents with potential microbial activity because theyalter the lipidic membrane of bacterial cellular membrane, and they can induce structuralchanges in proteins and oxidative damage in the DNA and RNA molecules andintracellular acidifications. Thus, BA resistance is an important selection criterion forpotentially probiotic strains, i.e. those that when administered in appropriate amountsexert a beneficial effect on the host. However, the molecular mechanisms by which BAsaffect cell viability remain to be elucidated. Therefore, the aim of the present work was toevaluate the effect of BAs such as cholic acid (CA), deoxycholic acid (DCA) andtaurodeoxycholic acid (TDCA), on the potentially probiotic strain Lentilactobacillus (L)parabuchneri CB12 on its main cellular components using Raman spectroscopy.The Raman spectral changes induced by CA at all evaluated concentration (0-0.25 mM)induce important changes in bacteria cell observing an increment in DNA and lipidspectral bands. On the other hand, DCA would indicate that the effect is associated withthe disruption of macromolecules, especially proteins, lipids and carbohydrates, at lowconcentrations (0.05-0.5 mM) and DNA at high concentrations (1-2 mM). In contrast, inthe presence of TDCA only slight modifications in lipids signals are observed at lowconcentrations (2.5-5 mM), and none changes at high concentration (7.5-10 mM)indicating a different interaction mechanism in relation the other BA. Finally, Ramanspectroscopy results a power tool to evaluate the cellular component changes of bacterialcell when it is affect by antimicrobial agent. These findings provide a deeperunderstanding of the interaction of ABs with bacterial and allow us to deepen ourunderstanding of their role as antimicrobial agents.