Fifteen strains of Lactobacillus and Bifidobacterium were screened based on their ability to adhere to hydrocarbons via the determination of cellular hydrophobicity. Lactobacillus acidophilus ATCC 314, L. acidophilus FTCC 0291, Lactobacillus bulgaricus FTCC 0411, L. bulgaricus FTDC 1311, and L. casei ATCC 393 showed greater hydrophobicity and, thus, were selected for examination of cholesterol-removal properties. All selected strains showed changes in cellular fatty acid compositions, especially total fatty acids and saturated and unsaturated fatty acids in the presence of cholesterol compared with those grown in the absence of cholesterol. In addition, we found that cells grown in media containing cholesterol were more resistant to sonication and enzymatic lysis compared with those grown without cholesterol. We further evaluated the location of the incorporated cholesterol via the insertion of fluorescence probes into the cellular membrane. In general, enrichment of cholesterol was found in the regions of the phospholipid tails, upper phospholipids, and polar heads of the cellular membrane phospholipid bilayer. Our results also showed that lactobacilli were able to reduce cholesterol via conversion of cholesterol to coprostanol, aided by the ability of strains to produce cholesterol reductase. Our results provided experimental evidence to strengthen the hypothesis that probiotics could remove cholesterol via the incorporation of cholesterol into the cellular membrane and conversion of cholesterol to coprostanol. The strains studied may be potential health adjunct cultures in fermented dairy products with possible in vivo hypocholesterolemic effects.
Probiotics are live organisms that are primarily used to improve gastrointestinal disorders such as diarrhea, irritable bowel syndrome, constipation, lactose intolerance, and to inhibit the excessive proliferation of pathogenic intestinal bacteria. However, recent studies have suggested that probiotics could have beneficial effects beyond gastrointestinal health, as they were found to improve certain metabolic disorders such as hypertension. Hypertension is caused by various factors and the predominant causes include an increase in cholesterol levels, incidence of diabetes, inconsistent modulation of renin and imbalanced sexual hormones. This review discusses the antihypertensive roles of probiotics via the improvement and/or treatment of lipid profiles, modulation of insulin resistance and sensitivity, the modulation of renin levels and also the conversion of bioactive phytoestrogens as an alternative replacement of sexual hormones such as estrogen and progesterone.
Lactobacillus acidophilus FTCC 0291, Lactobacillus bulgaricus FTCC 0411, Lactobacillus casei FTCC 0442, Lactobacillus fermentum FTD 13 and Bifidobacterium bifidum BB 12 were screened for their -galactosidase activity over 24 h. Lactobacillus bulgaricus FTCC 0411 and L. fermentum FTD 13 showed highest -galactosidase specific activity and were selected to be incorporated into tofufa for a storage study of 9 days at 25 and 4 °C. The viability of both probiotics in tofufa exceeded 10 6 CFU/g and was maintained over storage, mainly contributed by their ability to hydrolyse oligosaccharides and to utilise the reducing sugars produced. The presence of probiotics in tofufa showed an increase in the concentrations of organic acids which led to a decrease in pH levels. This exhibited a preservative effect, where total aerobes and total anaerobes were 2 log 10 CFU/g lower than the control. Probiotics in tofufa also liberated peptides with angiotensin-converting enzyme (ACE) inhibitory properties. Consistent viability and high proteolytic activity of probiotics in tofufa during storage suggested that tofufa is a suitable carrier for live probiotics with bioactive potential.
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