They include the assimilation of cholesterol, cholesterol binding to the signaling pathway bacterial cell wall, microbial transformation of cholesterol to coprostanol, and enzymatic deconjugation of bile salts (7, 8, 11, 12). Gilliland et al. (7) found that certain Lactobacillus acidophilus strains could assimilate the cholesterol in the growth medium, thus making it unavailable for absorption from the intestines into the blood. Another plausible mechanism of cholesterol removal is the binding of cholesterol to bacterial cells. Nakajima et al. (8) focused on the cholesterol-lowering activity of milk fermented with an EPS-producing lactic acid bacterium. The authors reported that EPS has a

potential to interfere with the absorption of cholesterol, or

of bile acids, from the intestines by binding and removing them from the body in a manner similar to ABT 199 the process that was reported for plant-based polysaccharides or dietary fiber. Artificial cell microencapsulation (immobilization) is a technique used to encapsulate biologically active materials in specialized ultra-thin semi-permeable polymer membranes (13). Jones et al. (6) examined the potential of artificial cell-microencapsulated genetically engineered Lactobacillus plantarum 80 (pCBH1) cells for bile acid deconjugation to lower cholesterol. Researchers found that microencapsulated cells deconjugated tested bile salts successfully. However, to the best of our knowledge, the literature contains no report evaluating cholesterol removal by immobilized cells using other possible Oxymatrine mechanisms. The aims of the present study were to evaluate: (i) the relationship between EPS production and cholesterol removal rates; (ii) cholesterol removal by dead and resting cells; (iii) the effect of cholesterol on EPS production; and (iv) the immobilization

effect on cholesterol removal by five strains of Lactobacillus delbrueckii subsp. bulgaricus, isolated from home-made yoghurt and selected according to their exopolysaccharide production capacity. Lactobacillus delbrueckii subsp. bulgaricus strains used in this study were obtained from the stock collection of Biotechnology Laboratory at Gazi University, Faculty of Science and Arts, Department of Biology (Ankara, Turkey). L. delbrueckii subsp. bulgaricus ATCC 11842 was from the American Type Culture Collection (Rockville, MD, USA) and the other strains were isolated from traditional home-made yoghurt. Their identity and EPS production capacity were confirmed as previously described (14). The cultures were maintained by subculturing 1% inocula into MRS broth (Lactobacillus medium according to de Man Rogosa & Sharpe; Merck, Darmstadt, Germany) and incubating them for 18 hr at 42°C. All of the Lactobacillus strains had been stored at −20°C in MRS broth with 10/100 ml glycerol, and subcultured twice until they were used in the experiments.