2015 Volume 21 Issue 5 Pages 685-693
The study aimed to isolate and characterize probiotic strains with potential cholesterol degrading activity. Fourteen lactic acid bacteria isolated from lamb meat were screened on mineral salt agar supplemented with 0.2% cholesterol (MSC agar). Cell-free supernatants (CFSs) of these isolates were used as a crude source of extracellular cholesterol degrading enzymes. CFSs of GMK01, GMK02 and GMK03 isolates displayed high ability to degrading cholesterol (86.4, 86.1 and 84.6%, respectively). These isolates were identified as Lactobacillus sakei GMK01, Lactobacillus rhamnosus GMK02 and Leuconostoc mesenteroides GMK03. Strains were resistant to low acidity (pH 2.5) and bile salts (0.3%), able to adhesion to Caco-2 cells and have low rate of antibiotic resistance. Living cells of these strains were able to degrade cholesterol in MSC broth even after treatment with simulated gastrointestinal juice. The maximum cholesterol degradation (about 90%) was obtained on the third day. 4-cholesten-3-one was detected as a degradation product of cholesterol by Leuconostoc mesenteroides GMK03. The studied strains degrade cholesterol by different mechanisms and may suggest a new possibility for the mechanism underlying cholesterol degradation by LAB. In conclusion, the isolated strains could be suggested as potential pharmaceutical probiotic strains for food industry and human nutrition.