Food and Beverages

The cholesterol removal by the isolated probiotic Lactococcus lactic subsp. lactis was investigated in vitro. The studied mechanisms included: (1) assimilation of cholesterol by growing cells, (2) deconjugation of bile via BSH; (3) coprecipitation of cholesterol with deconjugated bile; (4) binding of cholesterol to the cellular membrane and (5) incorporation of cholesterol into the cell membrane. Cholesterol assimilated by growing cells (43.70%) was significantly higher than that of resting cells (12.93%) and their counterparts of dead cells (6.35%). Micrograph of Transmission Electron Microscopy (TEM) showed a bright zone around the cells growing with cholesterol as the indication for cholesterol adsorption to the bacterial cell wall. Comparing the IR spectra of Lactococcus lactic subsp. lactis and Lactococcus lactic subsp. lactis grown with cholesterol in the database of FT-IR spectroscopy showed that most obvious changes in the intensity were detected in sulfamide bonds, P-H stretching and C≡C group. There was a difference in fatty acids distribution pattern of cells grown with or without cholesterol. Lactococcus lactic subsp. lactis was able to deconjugate sodium glycholate and sodium taurocholate and their mixture with more tendencies toward sodium glycholate. Cholesterol was co-precipitated with the deconjugated form of each of sodium glycholate and sodium taurocholate or their mixture at varying levels. Precipitation of cholesterol upon deconjugation of

sodium glycholate was higher (5.53 μg/ml) as compared to that upon deconjugation of sodium taurocholate (3.7 μg/ml). The present study confirmed the ability of the isolated probiotic Lactococcus lactic subsp. lactis to reduce cholesterol level through different mechanisms. Consequently, its suitability for application in functional food formulations particularly when cholesterol reduction in food is targeted.