COMPARISONS OF FRESHLY ISOLATED STRAINS OF LACTOBACILLUS-ACIDOPHILUS OF HUMAN INTESTINAL ORIGIN FOR ABILITY TO ASSIMILATE CHOLESTEROL DURING GROWTH

Fecal isolates of Lactobacillus acidophilus were obtained from human volunteers and tested for bile tolerance, the ability to deconjugate bile salts, and the ability to assimilate (take up) cholesterol during growth. One hundred and twenty-three of the 304 isolates of lactobacilli obtained were identified as L. acidophilus. In most cases, isolates of L. acidophilus from the same volunteer varied significantly in the amount of cholesterol assimilated, bile salt deconjugated, and bile tolerance. The two cultures from each of nine volunteers that assimilated the most cholesterol were compared as a group to select the most active cultures. Lactobacillus acidophilus ATCC 43121 (an isolate from the intestines of a pig, which in an earlier study aided significantly in controlling serum cholesterol in pigs) was included in this comparison. Significant variation in the ability to assimilate cholesterol was observed among these isolates from different volunteers. Eight of 17 isolates assimilated numerically but not significantly more cholesterol than L. acidophilus ATCC 43121, and 4 isolates assimilated significantly less. Bile tolerance and bile salt deconjugation also varied significantly among the selected isolates. Six of the selected isolates were quantitatively but not significantly better able to deconjugate bile salts than L. acidophilus ATCC 43121, but none was significantly more bile tolerant. Based on characteristics tested, isolates B7, D3, L1, 016, and 017 have the most potential of those included in this study for use as dietary adjuncts to lower human serum cholesterol.