Selective Enumeration of Lactobacillus acidophilus for Probiotic Formulations

Abstract

Probiotic microorganisms have been utilized for many years in food processing, preservations and for nutraceutical health benefits. There are a large number of pharmaceutical formulations containing probiotic microorganisms available in the market worldwide. Majority of these organisms are the members specifically from genera Lactobacillus, Lactococcus and Bifidobacterium. A number of media have been proposed for selective or differential enumeration of lactobacilli and bifidobacteria in mixed populations. The development of selective medium using different types of ingredients and antibiotic are well practiced. In the present study we have developed a selective medium for the enumeration of Lactobacillus acidophilus by utilizing the antibiotic ofloxacin resistance of the organism in Lactobacilli MRS-agar. Samples were analyzed by determining viable counts in reference Lactobacilli MRS agar and selective Lactobacilli MRS-ofloxacin agar media. The results were statistically analyzed to evaluate the precision, accuracy, reproducibility and selectivity of the method developed. Thus MRS containing ofloxacin medium can be used for selective enumeration of Lactobacillus acidophilus strains available in commercial formulations containing Bifidobacterium species.