Effect of ox gall on cholesterol reduction ability of probiotics: a comparative in vitro study

Researchers have been investigating new methods for reducing cholesterol in human serum and foods, aiming to replace chemical treatments. One of the latest approaches involves the use of probiotics. This study aimed to evaluate and compare the ability of two probiotic bacteria Lactobacillus acidophilus PTCC1643 (Lb. acidophilus) and Lactobacillus plantarum PTCC1896 (Lb. plantarum) to reduce cholesterol levels in vitro. Accordingly, acid and bile tolerance, lipolytic activity, bile salt hydrolase activity, cholesterol-lowering capacity, and SEM imaging in the presence and absence of ox gall were assessed. Results showed that the maximum cholesterol reduction was taken place by Lb. plantarum and Lb. acidophilus occurred in a medium without ox gall, with reductions of 74.53% and 45.63%, respectively (p < 0.01). In the medium supplemented with ox gall, Lb. acidophilus performed better than Lb. plantarum, with reductions of 36.64% and 30.89%, respectively (p < 0.01). Scanning electron microscopy micrographs also revealed that cholesterol was assimilated into the cell walls of Lb. plantarum, contributing to cholesterol reduction in MRS broth containing ox gall. Both strains showed significant tolerance to pH levels of 2–3 and demonstrated good resistance to 0.3% (w/v) ox gall (p < 0.01). Additionally, Lb. plantarum showed a greater ability to deconjugate bile salts, which contributed to cholesterol reduction. As neither bacterium exhibited lipolytic activity, they may be suitable for incorporation into food matrices. Consequently, Lb. plantarum demonstrated more cholesterol reduction than Lb. acidophilus in vitro, but further experiments are needed to use its functional activity in food products.