Browsing by Author "Souther, Nicole Elaine"

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    Development of a Multiplex PCR to Identify Lactobacillus acidophilus NCFM, a Probiotic Organism
    (2010-04-02) Souther, Nicole Elaine; Dr. Lee-Ann Jaykus, Committee Member; Dr. Sophia Kathariou, Committee Member; Dr. Todd Klaenhammer, Committee Chair
    Lactobacillus acidophilus NCFM is a probiotic organism used in food products and dietary supplements since 1972. A recent study recovered strains of L. acidophilus from various food- and probiotic products currently being used in the food industry demonstrating a genetic fingerprint comparable to that of L. acidophilus NCFM. Reliable strain identification in commercial products is of paramount in regards to food safety and consistent probiotic features. A multiplex PCR system to identify Lb. acidophilus NCFM was established and used to distinguish this strain from other Lactobacillus species and Lactobacillus acidophilus strains. The genome of this organism revealed the presence of seven distinct transposase elements. Three of these genes were found in multiple, highly conserved copies ranging from two to six replicas, indicating relatively recent multiplication events. A total of four different primer sets were designed around four selected transposase genes to generate semi-conserved PCR products. Various strains of L. acidophilus, including NCFM, were tested with the primer sets. The multiplex reaction identified six of these strains as NCFM, or closely related to Lb. acidophilus NCFM. Five of the L. acidophilus strains showed distinguishing banding patterns. We were able to demonstrate the use of multiplex PCR to identify L. acidophilus NCFM and NCFM-related strains, and distinguish these from other species and closely-related strains of L. acidophilus.