Evaluation of Bile Salt Hydrolases, Cholesterol-Lowering Capabilities, and Probiotic Potential of Enterococcus faecium Isolated From Rhizosphere

Abstract

Bile salt hydrolase (BSH) activity, hypo-cholesterolemic effect, and probiotic properties have been reported for Enterococcus strains isolated from animal and human gut and fermented foods but not for strains isolated from environmental niches, like aquatic and terrestrial plants, soil, and water. The present study is the first report on isolation of Enterococcus faecium from rhizospheric soils that harbor the bsh gene, remove cholesterol in vitro , and possess essential and desirable probiotic attributes. Fifteen samples were collected from different sites located in northern, southern, and central regions of India, of which five yielded pure colonies that were named LR2, LR3, ER5, LR13, and VB1. These were identified by 16S rRNA gene sequencing as E. faecium and evaluated for BSH activity, cholesterol-lowering potential in vitro , and probiotic properties. Our results indicated that all the strains were capable of surviving the harsh conditions of the gastrointestinal tract and did not harbor any of the virulence genes. Though all strains showed the presence of bsh and potential for cholesterol removal, E. faecium strain LR13 showed a remarkable cholesterol removal capability and vancomycin susceptibility and possessed most of the desirable and essential attributes of a probiotic. Hence, it seems to be a fairly promising probiotic candidate that needs to be further evaluated in in vivo studies, especially for its hypo-cholesterolemic potential.

Probiogenomics of Lactobacillus delbrueckii subsp. lactis CIDCA 133: In Silico, In Vitro, and In Vivo Approaches

“…The CIDCA 133 tolerance to acidic gastric juice simulated with pepsin solution (pH 3.0) was performed according to Singhal et al [ 54 ]. Briefly, 3 g/L of pepsin (Sigma–Aldrich, St. Louis, MO, USA) was diluted in 0.5% sterile NaCl (pH 3.0) (Vetec, Rio de Janeiro, Brazil).…”

High Prevalence of Drug Resistance and Class 1 Integrons in Escherichia coli Isolated From River Yamuna, India: A Serious Public Health Risk

“…The contents of the PCR mixture were 1 × PCR buffer (1.5 MgCl 2 , 1.5 mM of KCl, 10 mM of Tris–HCl, and 0.1% Triton X-100), 200 μM of the four dNTPs, 1 U of Taq DNA polymerase (New England Biolabs, Ipswich, MA, United States), 10 pmol of forward and reverse primers, and 1 ng of genomic DNA in a final volume of 25 μl. The PCR conditions and methods for purification of PCR amplicons and sequencing have been described earlier ( Singhal et al, 2019 ). Briefly, the PCR amplicons were purified by HiYield TM extraction kit (RBC Bioscience, New Taipei City, Taiwan) and sequenced at a commercial facility using Sanger sequencing (Invitrogen BioServices India Pvt.…”

Probiotic Potential and Cholesterol-Lowering Capabilities of Bacterial Strains Isolated from Pericarpium Citri Reticulatae ‘Chachiensis’

“…Bile salt hydrolase (BSH) activity was assessed using the method described previously [29,30] with modification. Sodium taurodeoxycholic acid (TDCA) and sodium glycodeoxycholic acid (GDCA) at 0.5% (w/v) were used as bile salt substrates.…”

“…The cholesterol removal ability was evaluated according to the method described previously [30] with modification. The overnight culture was inoculated at 1 mL/100 mL in LB or MRS medium containing cholesterol at a final concentration of 100 µg/mL.…”

“…Unfortunately, using TDCA and GDCA as BA substrates, the positive BSH activity as a white precipitation zone around the colonies was not observed in our experiment. Since non-concordance between BSH phenotypic assay and presence of bsh gene was reported recently in Enterococcus faecium isolated from rhizosphere [30], we further searched for the bsh gene in these eight isolates. According to the bsh genes in similar strains as reference, touchdown PCR successfully retrieved six bsh genes from five isolates, including N17-02, N17-12, Y11-38, X16-66 and N15-22.…”