Abstract

Ten commercially available probiotic products were collected from the local market of Lahore, Pakistan; including dairy, freeze dried products and fruit drinks. These products were examined by using culture dependent methods, SDS-PAGE as well as by visualization of denaturing gradient gel electrophoresis (DGGE) band profiles under UV light. Identical results of the DGGE and culture-dependent analysis of the 10 probiotic products were found. A DGGE analysis of five products (Nestle yogurt, Haleeb flavored yogurt, Haleeb yoghurt, Freeze-dried product and Nestle fruit yogurt) detectedBifidobacterium lactis, Streptococcus thermophilus, Lactobacillus delbrueckii subsp.bulgaricus, Bifidobacterium lactis, Lactobacillus casei, Lactobacillus acidophilus,Lactobacillus rhamnosus, Bacillus cereus and Streptococcus thermophilus that were the same as with conventional isolation procedures. For the remaining five products (Nestle nido, Haleeb Xtra energy milk, Haleeb Labban, Haleeb chadder cheese, and freeze-dried culture), DGGE analysis was able to detect more species (L. delbrueckii subsp.bulgaricus, L. rhamnosus, L. acidophilus, L. casei, and L. acidophilus) than were recovered by culture-dependent methods. The present study has proved that the PCR-DGGE and and phenotypic identification methods may result in a very powerful tool for both qualitative and quantitative analyses of all kinds of (bacterial) fermentation products.

Key words: Probiotic products, polyerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method, culture-dependent analysis.