Diverse conditions contribute to the cholesterol-lowering ability of different Lactobacillus plantarum strains.

It has been reported that Lactobacillus can remove cholesterol and thus might play an important role in lowering cholesterol in humans, but the underlying mechanism is still controversial. To confirm whether different strains have different cholesterol-lowering mechanisms, we explored the cholesterol-lowering abilities of different Lactobacillus plantarum strains, and the factors influencing their abilities. We found that all nine strains reduced the cholesterol concentration to some extent, but there were significant differences among them. In MRS broth, L. plantarum AR113 and AR171 showed the greatest cholesterol-lowering abilities of 27.89% and 19.90%, respectively, but AR501 and AR300 only showed reductions of 0.34% and 0.91%, respectively. Upon addition of 0.1% ox bile, the cholesterol-removal capability of most strains increased. L. plantarum AR511 showed the highest cholesterol removal rate, which increased from 5.8% to 37.14%, i.e., by a factor of approximately 6.4, but there was no significant change in the cholesterol removal rate of AR171. These results suggested that the effect of ox bile on the cholesterol-lowering ability was strain-specific. Except for the strains AR171, AR237 and AR495, the cholesterol-removal ability of the remaining six strains was positively correlated with the amount of free bile acid released. The addition of a bile salt hydrolase inhibitor had some effect on the cholesterol-removal ability of the six strains of bacteria other than AR171, AR237 and AR495, but little influence on the latter three. The effect of BSH was strain-specific. Similarly, the effect of pH was also strain-specific. Taken together, these results suggest that different strains of L. plantarum have different cholesterol-lowering capacities and different influencing factors. Therefore, further research is needed to explore the exact mechanism by which different strains lower cholesterol.