Relationship between bile salt hydrolase activity, changes in the internal pH and tolerance to bile acids in lactic acid bacteria

• Published in: Biotechnology letters 2012-08, Vol.34 (8), p.1511-1518
• Main Authors: Bustos, Ana Yanina, Saavedra, Lucila, de Valdez, Graciela Font, Raya, Raúl Ricardo, Taranto, María Pía
• Format: Article
• Language: English
• Subjects: Acids; Amidohydrolases - genetics; Amidohydrolases - metabolism; Applied Microbiology; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bile; bile acids; Bile Acids and Salts - metabolism; Bile Acids and Salts - pharmacology; bile salts; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; cell viability; Cellular biology; Enzymes; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Hydrolysis; Intracellular Space - chemistry; Intracellular Space - enzymology; Lactic acid; lactic acid bacteria; Lactobacillales - drug effects; Lactobacillales - enzymology; Lactobacillales - genetics; Lactobacillales - metabolism; Life Sciences; Microbial Viability; Microbiology; Microorganisms; Original Research Paper; Strain; Survival; Tolerances; Toxicity
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-012-0932-5

The effect of the conjugated bile acid (BA) on the microbial internal pH (pHin) values in lactic acid bacteria with and without ability to hydrolyze bile salts (BSH[+] and BSH[−] strains, respectively) was evaluated. BSH(+) strains showed a gradual increase in the pHin following the addition of conjugated BA; this behavior was more pronounced with GDCA than with TDCA may be due to the higher affinity of BSH for the glyco-conjugates acids. Conversely, the BSH(−) strains showed a decrease in internal pH probably as a consequence of weak acid accumulation. As expected, a decrease in the cytoplasmatic pH affected the cell survival in this last group of strains, while the BSH(+) strains were more resistant to the toxic effect of BA. PURPOSE OF WORK: To evaluate bile salt hydrolase activities, changes in the internal pH and cell survival to bile acids in lactic acid bacteria to establish the relationship between these parameters.