Moreno Caren N, Gomez Jorge N, Taranto María P, Ledesma Ana E, Bustos Ana Y
Centro de Investigación en Biofísica Aplicada y Alimentos (CIBAAL-UNSE-CONICET), RN 9, Km 1125, Santiago del Estero 4206, Argentina.
Centro de Referencia de Lactobacilos (CERELA-CONICET), Chacabuco 145, San Miguel de Tucumán 4000, Argentina.
BioTech (Basel). 2024 Aug 2;13(3):29. doi: 10.3390/biotech13030029.
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 (glycodeoxycholic, glycocholic, taurodeoxycholic, taurocholic acids) and free BAs [cholic acid (CA) and deoxycholic acid (DCA)] on the survival, biological molecules, and structural and surface properties of two potential probiotic lactic acid bacteria (LAB) was evaluated. For this, viability assays, Raman spectroscopy, scanning electron microscopy (SEM), and zeta potential (ZP) measurements were employed. Our results evidenced that free BAs were more toxic than conjugates, with CA being significantly more harmful than deoxycholic acid (DCA). RAMAN studies show that BAs modify the bands corresponding to proteins, lipids, carbohydrates, and DNA. SEM showed that BAs cause surface distortions with depressions and fold formation, as well as incomplete cell division. DCA was the one that least altered the ZP of bacteria when compared to CA and taurodeoxycholic acid, with gradual changes towards more positive values. In general, the magnitude of these effects was different according to the 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 solid evidence on the effects of BAs on LAB that will allow for the development of strategies by which to modulate the composition of the microbiota positively.
胆汁酸（BAs）是肠道微生物群组成和代谢活性的主要内源性调节剂。在本研究中，评估了共轭胆汁酸（甘氨脱氧胆酸、甘氨胆酸、牛磺脱氧胆酸、牛磺胆酸）和游离胆汁酸[胆酸（CA）和脱氧胆酸（DCA）]对两种潜在益生菌乳酸菌（LAB）的存活率、生物分子以及结构和表面性质的影响。为此，采用了活力测定、拉曼光谱、扫描电子显微镜（SEM）和zeta电位（ZP）测量。我们的结果表明，游离胆汁酸比共轭胆汁酸毒性更大，其中胆酸比脱氧胆酸（DCA）的危害显著更大。拉曼研究表明，胆汁酸会改变与蛋白质、脂质、碳水化合物和DNA对应的谱带。扫描电子显微镜显示，胆汁酸会导致表面出现凹陷和褶皱形成的扭曲，以及细胞分裂不完全。与胆酸和牛磺脱氧胆酸相比，脱氧胆酸对细菌zeta电位的改变最小，且会逐渐向更正的值变化。总体而言，这些影响的程度因胆汁酸及其浓度而异，在胆酸存在时更为明显，即使在低浓度下也是如此，这可以解释其更大的抑制作用。这项工作为胆汁酸对乳酸菌的影响提供了确凿证据，这将有助于制定积极调节微生物群组成的策略。
