In other words, cholesterol stimulated EPS production. Free bile salts are less soluble than conjugated bile salts, resulting in lower absorption in the intestinal lumen. Deconjugation of bile acids can reduce serum cholesterol levels by increasing the formation of new bile acids that are needed to replace those that have escaped the enterohepatic circulation (30). L. delbrueckii subsp. bulgaricus B3 strain, which has the highest EPS production and cholesterol removal capacity, was selected for the immobilization Pifithrin-�� study. The results may indicate that an interaction occurs between the alginate used for immobilization and the cholesterol in the medium.
In other words, theoretically, cholesterol could be bound to immobilization material. However, to the best of our knowledge, there are no published reports on cholesterol removal by immobilized cells. Results of this study indicate that the use of immobilized probiotic strains, which is effective for cholesterol removal, has a positive influence on cholesterol removal features of the organisms. The results R788 mouse further suggest that immobilized
B3 cells are more resistant to 3 mg/ml oxgall concentration than the free cells. Chandramouli et al. (31) reported that when the immobilized test bacteria were subjected to high bile concentration (1 mg/100 ml bile) there was a significant increase in viable cell counts compared to the free cells under similar conditions. Thus, the immobilization method described in this study may be effectively used to protect the viability and probiotic features of the strains. To the best of our knowledge, the literature
contains no reports on cholesterol removal by Lactobacillus bacteria of 3-oxoacyl-(acyl-carrier-protein) reductase yoghurt origin. The cholesterol removal mechanism by binding or adhering to the bacteria cells, especially to the EPS produced by the bacteria and surrounding the bacterial cells as a capsule, has potential importance in the control of serum cholesterol concentration in humans. In our study, all of the Lactobacillus stains tested removed cholesterol from media during growth. Among them, L. delbrueckii subsp. bulgaricus B3, which has distinctive features in EPS production and cholesterol removal capacity, removed the highest amount of cholesterol. Furthermore, the immobilized B3 strain efficiently reduced cholesterol in the growth medium and, also, the immobilization process raised the bile tolerance of the cells. Results of the present study suggest that immobilized B3 cells have several advantages over the free counterparts. Based on these findings, the combination of a probiotic culture that can remove cholesterol and a strain that has high EPS production capacity could be used to manufacture a fermented dairy product that would have enhanced anti-cholesterolemic activity. Some parts (isolation of cultures and EPS production) of this research were supported by TUBITAK (TBAG-2090(101T129)).