title: Relationship between bile salt hydrolase activity, changes in the internal pH and tolerance to bile acids in lactic acid bacteria.
abstract: 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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA-CONICET), Chacabuco 145, T4000ILC, San Miguel de Tucumán, Argentina.
authors.forename: Ana Yanina
authors.initials: AY
authors.lastname: Bustos
authors.forename: Lucila
authors.initials: L
authors.lastname: Saavedra
authors.forename: Graciela Font
authors.initials: GF
authors.lastname: de Valdez
authors.forename: Raúl Ricardo
authors.initials: RR
authors.lastname: Raya
authors.forename: María Pía
authors.initials: MP
authors.lastname: Taranto
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D042541:Intracellular Space / Q000737:chemistry / Q000201:enzymology; D056546:Lactobacillales / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D050296:Microbial Viability
chemical_list: D001426:Bacterial Proteins; D001647:Bile Acids and Salts; D000581:Amidohydrolases; C023154:choloylglycine hydrolase