Bile Salt Hydrolase Activity and Resistance to Toxicity of Conjugated Bile Salts Are Unrelated Properties in Lactobacilli

Abstract

Bacteria of numerous species isolated from the human gastrointestinal tract express bile salt hydrolase (BSH) activity. How this activity contributes to functions of the microorganisms in the gastrointestinal tract is not known. We tested the hypothesis that a BSH protects the cells that produce it from the toxicity of conjugated bile salts. Forty-nine strains of numerous Lactobacillus spp. were assayed to determine their capacities to express BSH activities (taurodeoxycholic acid [TDCA] hydrolase and taurocholic acid [TCA] hydrolase activities) and their capacities to resist the toxicity of a conjugated bile acid (TDCA). Thirty of these strains had been isolated from the human intestine, 15 had been recovered from dairy products, and 4 had originated from other sources. Twenty-six of the strains expressed both TDCA hydrolase and TCA hydrolase activities. One strain that expressed TDCA hydrolase activity did not express TCA hydrolase activity. Conversely, in one strain for which the assay for TDCA hydrolase activity gave a negative result there was evidence of TCA hydrolase activity. Twenty-five of the strains were found to resist the toxicity of TDCA. Fourteen of these strains were of human origin, nine were from dairy products, and two were from other sources. Of the 26 strains expressing both TDCA hydrolase and TCA hydrolase activities, 15 were resistant to TDCA toxicity, 6 were susceptible, and 5 gave inconclusive results. Of the 17 strains that gave negative results for either of the enzymes, 7 were resistant to the toxicity, 9 were susceptible, and 1 gave inconclusive results. These findings do not support the hypothesis tested. They suggest, however, that BSH activity is important at some level for lactobacillus colonization of the human intestine.

Probiotic properties of Enterococcus faecium CE5-1 producing a bacteriocin-like substance and its antagonistic effect against antibiotic-resistant enterococci in vitro

“…It has been suggested that the major effect of bile acids would be the disaggregation of the lipid bilayer structure of the cell membrane. The tolerance to bile salts was initially associated with the presence of bile salt hydrolase activity (Moser and Savage, 2001;Taranto et al, 2006).…”

Characterization of Probiotic Abilities of Lactobacilli Isolated from Iranian Koozeh Traditional Cheese

“…Table 1 shows that some strains were able to grow in the presence of conjugated bile salts while they were not able to deconjugate them. This fact can be attributed to the ability of isolates to express bile salt hydrolase (BSH) activity which is not related to their ability to resist the toxicity of conjugated bile salts [Moser & Savage, 2001]. …”

Identificación preliminar in vitro de propiedades probióticas en cepas de S. cerevisiae

“…Otro mecanismo por el cual la levadura es resistente a altas concentraciones de sales biliares, se centra en la acumulación de polioles y glicerol, como mecanismo para regular la presión osmótica de la célula. Moser y Savage (18), indicaron que las especies de levaduras que toleran sales biliares contribuyen a la función de los microorganismos en el tracto gastrointestinal (19); lo cual deberá ser demostrado posteriormente con nuestras sepas.…”