17A-3 |
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S. A. IBRAHIM1, O. A. Hassan1, A. Shahbazi2, and C. W. Seo1. (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 The use of bifidobacteria and lactobacillus as dietary adjuncts or as a probiotic is a subject of intense and growing interest. Several reports have indicated that probiotics have the ability to provide several health benefits. However, in order for these cultures to manifest beneficial effects, they need to achieve a desirable mass through aggregation. Consequently, the ability of probiotics to aggregate is a desirable property sought for use in commercial food preparations. Adherence of bacterial cells is usually related to cell surface characteristics. The objective of this study was to determine cell surface characteristics and autoaggregation behavior of bifidobacteria and Lactobacillus reuteri. Thirty-seven strains of bifidobacteria and six strains of Lactobacillus reuteri were used in this research. Overnight cultures were suspended in 10mM potassium phosphate buffer and treated with one of the following solvents (1% v/v) to determine cell hydrophobicity: Chloroform, ethyl acetate, hexadecane, toluene and xylenes. Electrophoretic mobility (EM) was measured to determine the cell surface net charge of the cultures. Autoaggregation behavior was determined using the adhesion assay. Results indicate that the tested strains are relatively hydrophobic. They display maximal affinity for an acidic solvent such as chloroform and low affinity for a basic solvent such as ethyl acetate. These results indicate that the tested strains are strong electron donors and weak electron acceptors. The EM data indicate that strains had negative charge at alkaline pH values. EM values decreased as the pH values of the media decreased. Results also show a positive relationship between autoaggregation and adhesion of the tested strains. The present study demonstrates that cell surface properties of probiotic cultures including lactobacillus and bifidobacteria have an impact on the autoaggregation behavior.
Session 17A, Dairy Foods: Cheese and microbiology
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