Mechanisms of cholesterol removal by lactobacilli under conditions that mimic the human gastrointestinal tract

Five strains of lactobacilli were studied for their ability to remove cholesterol in vitro under conditions that mimic the human gastrointestinal tract. The highest assimilation of cholesterol was observed in media supplemented with oxgall and the lowest in the presence of taurocholic acid. Scanning electron micrographs showed that cholesterol was adhered to the cellular surface of lactobacilli cells. Resting and dead cells were able to remove cholesterol although in small amounts. Additionally, inhibition of cholesterol micelles formation was observed in the presence of bile salts. All strains were able to deconjugate bile salts, where higher deconjugation was observed in the presence of sodium glycocholate compared with other bile salts studied. All strains also exhibited bile salt hydrolase activity and most strains showed higher substrate specificity towards glycine-conjugated bile than towards taurine-conjugated bile. The results indicated that lactobacilli could remove cholesterol in vitro via various mechanisms, and may exert such hypocholesterolaemic effects in vivo.