| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 92 === Probiotic products from lactic acid bacteria (LAB) are widely used as human food and animal feed supplements. In addition to the evaluation of probiotic functions, molecular diagnostic methods are used for the identification of LAB cells. Two major subjects were included in this study. One was the development of DNA methods for identification of some Lactobacillus species. The other was evaluation of the safety for lactic acid bacteria strains screened with good probiotic properties. For molecular identification, we developed specific polymerase chain reaction (PCR) primers based on the DNA sequence of tuf gene, and used of these primers for the identification of lactic acid bacteria species including Lactobacillus acidophilus、L. agilis、L. crispatus and L. ruminis. 194 clinical strains isolated from infant stool samples were PCR assayed and 2 L. acidophilus、2 L. crispatus and 4 L. ruminis were identified. Furthermore, we screened lactic acid bacteria (LAB) strains from porcine intestine and evaluate their functional properties in previously study. We found a strain of Lactobacillus acidophilus LA5 as a probiotic to prevent the infection of Salmonella typhimurium is one of the major food pathogen which may cause human salmonellosis and animal diarrhea cases. The present study was conducted to evaluate the toxicity of the strain L. acidophilus LA5 in Wistar rats on dietary administration at concentrations of 2.1×1011, 1.05×1011 and 4.2×109 CFU/ kg for 28 days. There were no adverse effects on the general condition and behavior, growth, feed and water consumption, hematology, clinical chemistry values, organ weights and histopathologic analysis. Results of this study demonstrated that consumption of the strain L. acidophilus LA5 was not associated with any obvious signs of toxicity in Wistar rats even following consumption of large quantities.
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