A new method for the in vitro determination of the bile tolerance of potentially probiotic lactobacilli

Abstract

A new in vitro method was developed to determine the bile tolerance of potentially probiotic lactobacilli. The overnight culture of various lactobacilli strains was inoculated into sterile, half-strength MRS broth supplemented with and without 0.3% (wt/vol) oxgall, buffered with 0.1 M sodium phosphate buffer at a final pH of 7.3, and incubated at 37 °C for 12 h under anaerobic conditions. The bile tolerance ability of the lactobacilli strains was expressed as the percentage of the propagation generations of the bacterial cells in the presence of oxgall to those in the absence of oxgall. The bile tolerance ability of 11 strains of 8 Lactobacillus species, including 3 bile salt hydrolase (BSH)-negative strains and 8 BSH-positive strains, was analyzed using the newly developed method and two traditional methods. The results showed that bile tolerance ability of the strains was considerably different depending on the analysis method used. The newly developed method mimics the physiological environment of the human small intestine, and avoids changes in pH and bile salt composition during the incubation period, which are drawbacks of the traditional bile tolerance test methods. Therefore, the analysis method developed in this study is more suitable to screen or compare the bile tolerance ability of lactobacilli strains.

Screening for Cholesterol-Lowering Probiotics from Lactic Acid Bacteria Isolated from Corn Silage Based on Three Hypothesized Pathways

“…The overnight cultures (16 h) of lactic acid bacterial strains were centrifuged at 10,000 g for 15 min, washed once with distilled water, and resuspended in MRS broth supplemented with a human bile salt mixture [44] (Sigma-Aldrich, total concentration of 4 mmol/L) at 1 × 10 8 CFU/mL. The cultures were incubated anaerobically for 2 h at 37 °C, centrifuged at 10,000 g for 15 min, and the supernatants (1 mL) were drawn for determining the conjugated bile salt concentrations using ion-pair high-performance liquid chromatography [45].…”

“…Bile tolerance ability of the cultures of lactic acid bacterial strains was measured according to the previous method [45]. Briefly, the overnight cultures (16 h) of lactic acid bacterial strains were inoculated (0.01‰, v / v ) into 1/2 strength buffered MRS broth (pH 7.3, 0.1 mol/L sodium phosphate) supplemented with and without 0.3% ( w / v ) oxgall (BD Difco, Sparks, MD, USA), and incubated for 12 h at 37 °C under anaerobic conditions.…”

Hamsters Are a Better Model System than Rats for Evaluating the Hypocholesterolemic Efficacy of Potential Probiotic Strains

“…The discrepancy of hypocholesterolemic efficacy of strain K16 in rats and hamsters can be explained in terms of the substrate preference of BSH of the strain and the different patterns of the biliary bile acid composition between rats and hamsters. The regularity of the substrate specificity of BSH found in strain K16 was not a specific example but a universal microbiological phenomenon in BSH‐active lactobacilli and bifidobacteria that generally exhibit greater hydrolysis toward GCBAs than toward TCBAs. A distinct difference is present in the biliary bile acid profiles including types and conjugation status between rats and hamsters.…”

Lactobacillus commensals autochthonous to human milk have the hallmarks of potent probiotics

“…Tolerating intestinal bile whose levels fluctuate from 0.15–0.3 % [58, 59] is also an essential prerequisite for candidate probiotic strains [60]. Using bovid bile, which is similar to human bile [61], gives an accurate in vitro assessment of bile tolerance. Only the L.…”