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URN etd-0803109-120907 Statistics This thesis had been viewed 5181 times. Download 4017 times. Author Wen-Lin Chen Author's Email Address No Public. Department Bioengineering Year 2008 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 74 Title Screening of the Lactobacillus species from the commercial yogurt in Japan that can inhibit growth of pathogenic bacteria in food. Keyword yogurt pathogenic bacteria in food probiotic Lactic acid bacteria Lactic acid bacteria probiotic pathogenic bacteria in food yogurt Abstract We isolated 6 Lactobacillus species from five commercial yogurts (A, B, C, D, E) of Japanese market. The strains were identified to be Lactobacillus paracasei ssp. paracasei (A), Lactobacillus acidophilus (B), Lactobacillus delbrueckii ssp. bulgaricus (C), Lactobacillus pentosus (D), and Lactobacillus plantarum (E-1), Lactobacillus delbrueckii ssp. delbrueckii (E-2) by API 50. The strains were cultured in MRS medium, and the cell concentrations by OD600nm were 8.5?0.9, 6.2?0.4, 7.4?0.8, 9.7?0.9, 9.6?0.7, 6.6?1.4, respectively, for Lactobacillus paracasei ssp. paracasei (A), Lactobacillus acidophilus (B), Lactobacillus delbrueckii ssp. bulgaricus (C), Lactobacillus pentosus (D), Lactobacillus plantarum (E-1), Lactobacillus delbrueckii ssp. delbrueckii (E-2). Lactobacillus species performed the most inhibition activity to E. coli, Salmonella, followed by Staphylococcus aureus, Bacillus cereus, and Shigella. There was no significant inhibition activity to Vibrio parahaemolyticus. The pH of the fermentation broth was adjusted to above 5.0, and inhibition activity for the broth to E. coli was no longer existed. We concluded that the inhibition activity was from the metabolites such as lactate and acetate in the broth. Advisor Committee Kow-Jen Duan - advisor
Files Date of Defense 2009-07-20 Date of Submission 2009-08-05