17A-2 |
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S. A. IBRAHIM1, S. A. Ahmad1, C. W. Seo1, and A. Shahbazi2. (1) Food Science & Nutrition Program, North Carolina A&T State Univ., Dept. of Human Environment & Family Sciences, 171-B Carver Hall, Greensboro, NC 27411-1064, (2) Bioenivromental Engineering Program, North Carolina A&T State Univ., Dept. of Natural Resources & Environmental Design, Carver Hall, Greensboro, NC 27411-1064 Probiotic supplements are becoming increasingly popular in the United States and Europe. Although there are many different types of probiotics, the most common are Lactobacillus bulgaricus, S. thermophilus, L. acidophilus, L. reuteri and bifidobacteria typically added to yogurt products. The effectiveness of probiotics is often compromised because of the difficultly live cultures have in traversing the digestive system, in particular surviving the effects of stomach secretions, notably bile salts. Most of these cultures require an acidic environment to grow and thrive. The presence of bile salts reduces pH levels and thus reduces culture survivability. The purpose of this work was to investigate the effect of Tween 80 and 20 on bile tolerance of L. reuteri. Six strains (CF 2F, DSM 20016, MF 14C, MM 7, MM 2-3, and SD 2112) of L. reuteri were used tested. These strains were grown in modified Trypticase-protease peptone-yeast extract (TPY) broth containing 0.0 or 0.4% bile alone or in combination with 1% Tween 20 or 80. The extent of bacterial growth was monitored by measuring the optical density at 610nm after various time intervals. Results showed that bile salts at 0.4% caused a significant reduction in the growth of all tested strains (P< 0.05). The addition of Tween, however, enhanced the bile tolerance of L. reuteri and thus reduced the inhibitory effect of the 0.4% bile salt solution to levels comparable to growth in the absence of bile salts. Both Tween 20 and 80 were effective in inducing bile tolerance , but the effects were different among the tested strains. MM 2-3 and MM 7 exhibited the highest tolerance to bile salts in the presence of Tween. These results demonstrate that Tween can be used to counter the inhibitory effects of bile salts on L. reuteri and can be used as supplement to improve the bile tolerance of probiotics.
Session 17A, Dairy Foods: Cheese and microbiology
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