Incidence of lactobacilli in milk

Lactobacillus species play a major role in fermented dairy products and also contribute to the therapeutic aspects of human health. Rapid methods are required for quality control of fermented dairy products, in vivo identification of probiotic strains and species of Lactobacillus and monitoring fermentation process. Though there is a fact that milk and dairy foods hampers DNA extraction due to the presence of proteins, fats and salts, Lactobacillus was identified by PCR from raw milk using modified DNA isolation technique. Incidence of lactobacillus in milk was found to be 85% among which L.delbrueckii ssp. bulgaricus was 60% and L.acidophilus was 40%. In order to validate the PCR for identification of lactobacilli from raw milk without pre-enrichment technique, the raw milk was intentionally inoculated with lactobacilli to make a concentration of 107, 105, 103, 10 cfu/ml and PCR was carried out. It concludes that at least 103 cfu/ml of lactobacilli is required to identify the lactobacillus from raw milk by PCR.