Research of cholesterol removal features and bile salt deconjugation effects of some lactic acid bacteria that can be used as probiotic

In this study, it has been targeted to determine the relationship between exopolysaccharide production and cholesterol removal ratios, and bile salt deconjugation activities of 5 strains of Lactobacillus delbrueckii subsp. bulgaricus, isolated from hand-made yoghurt and selected according to exopolysaccharide production capacity. Effect of cholesterol and different bile concentrations on growth was tested. It was found that cholesterol stimulated growth and according to increasing bile concentrations from 0,0 to 0,3% viability of the strains decreased. The viability of the strains was found between 0%-24% in 0,3% bile concentration. It has been studied influence of different bile concentrations on cholesterol removal. It has been confirmed that strains which produce high amount of exopolysaccharide (B3, ATCC 11842, G11) were able to remove much cholesterol from the medium than those produce low amount of exopolysaccharide (B2, A13) and the highest cholesterol removal (31%) was observed by strain B3 in 0,3% bile concentration. It has been determined cholesterol removal by resting and dead cells and it was found between 4-14% and 3-10%, respectively. For immobilization study, B3 strain which produce high amount of exopolysaccharide, resistant to bile and effective in cholesterol removal was selected. Cholesterol removal by immobilized and free cells was studied and it has been determined that immobilized cells were more effective. Influence of cholesterol on exopolysaccharide production has been tested and it was found that cholesterol stimulated production. Deconjugation activity of the strains on taurocholic acid was studied and it was confirmed between 15,0- 35,5%.