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

ANA YANINA BUSTOS; LUCILA SAAVEDRA; GRACIELA FONT DE VALDEZ; RAÚL RICARDO RAYA; MARÍA PÍA TARANTO

BIOTECHNOLOGY LETTERS

SPRINGER

Lugar: Berlin; Año: 2012 vol. 34 p. 1511 - 1518

0141-5492

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