Probiotic properties of Enterococcus strains isolated from traditional naturally fermented cream in China

Abstract

SummaryThe purpose of this study was to evaluate the probiotic properties of Enterococcus strains isolated from traditional naturally fermented cream in China. Four E nterococcus isolates showed high cholesterol removal ability in media were identified as E nterococcus durans (KLDS 6.0930 and 6.0933) and E nterococcus faecalis (KLDS 6.0934 and 6.0935) by 16S rRNA and pheS gene sequences, respectively, and selected for further evaluation. In order to assess the probiotic potential and safety of these strains, the property of four E nterococcus strains were examined, including acid and bile tolerance, adherence to Caco‐2 cells and antibiotics susceptibility. All four strains showed potential cholesterol assimilation, de‐conjugation of bile salts and/or cholesterol degradation to remove cholesterol in vitro. In addition, the potential effect of E. durans KLDS 6.0930 on serum cholesterol levels was evaluated in Sprague‐Dawley rats. After 4 weeks administration, compared with rats fed a high‐cholesterol diet without lactic acid bacteria supplementation, there was a significant (P < 0.05) decrease in the total cholesterol and low‐density lipoprotein cholesterol levels in the serum of rats treated with KLDS 6.0930. Furthermore, total bile acid level in the feces was significantly (P < 0.05) increased after KLDS 6.0930 administration. These observations suggested that the strain E. durans KLDS 6.0930 may be used in the future as a good candidate for lowering human serum cholesterol levels.

Evaluating the Safety of Potential Probiotic Enterococcus durans KLDS6.0930 Using Whole Genome Sequencing and Oral Toxicity Study

“…Despite the aforementioned cell surface factors, the genome of E. durans KLDS6.0930 also carries two fibronectin-binding proteins (LIU_RS07910 and LIU_RS10480) and an S-layer protein (LIU_RS11695), which may contribute to its adhesion. In addition, our previous study (Guo et al, 2016) showed that E. durans KLDS6.0930 could adhere to Caco-2 cells in vitro . As described below, we also demonstrated that E. durans KLDS6.0930 could colonize the cecum in vivo .…”

“…Minimum inhibitory concentrations (MICs) for antibiotics (ampicillin, penicillin, vancomycin, erythromycin, tetracycline, gentamicin, kanamycin, clindamycin, ciprofloxacin, trimethoprim, and rifampicin) against E. durans KLDS6.0930 were determined using a 96-well plate gradient dilution method (Guo et al, 2016a). Susceptibility was determined on the criteria adopted by European Food Safety Authority (EFSA) for the assessment of bacterial resistance to antibiotics (EFSA, 2012a).…”

“…Furthermore, some Enterococcus spp. have been shown beneficial properties, such as immune system regulation, normal intestinal microflora maintenance, antitumor activity, antimicrobial activity, antioxidant activity, and lowering cholesterol levels (Pieniz et al, 2014; Molina et al, 2015; Guo et al, 2016; Li P. et al, 2017). They are therefore frequently used as probiotics to promote human and animal health, or treat diseases such as diarrhea, irritable bowel syndrome, or antibiotic-associated diarrhea (Franz et al, 2011).…”

“…Previous in vitro and in vivo studies indicated that E. durans KLDS6.0930 possesses potential probiotic properties included acid and bile tolerance, adherence to Caco-2 cells and a cholesterol-lowering effect (Guo et al, 2016). The genome of E. durans KLDS6.0930 was the first whole genome sequence of E. durans and has been used as representative genome by GenBank.…”

Cholesterol reduction in vitro by novel probiotic lactic acid bacterial strains of Enterococcus isolated from healthy infants stool

“…Also, Pereira and Gibson (2002) reported high cholesterol removal ability (47%) by lactic acid bacteria and bifidobacteria isolated from human gut in broth media containing 100 µg/ml cholesterol. Guo et al (2016) reported cholesterol reduction (41.29 to 56.61%) from liquid media containing 100 µg/ml of cholesterol by Enterococcus strains. Excessive cholesterol concentration may suppress bacterial ability of cholesterol reduction.…”