METHOD FOR THE DIFFERENTIATION AND QUANTIFICATION OF LACTIC BACTERIA AND BIFIDOBACTERIA IN FERMENTED MILKS, USING SELECTIVE ANTIBIOTIC-FREE CULTURE MEDIA

摘要

The invention relates to a method for the differentiation and quantification of lactic bacteria and bifidobacteria in fermented milks, using selective antibiotic-free culture media. The method can be used for the differential and selective quantification of four species of lactic bacteria (S. thermophilus, L. bulgaricus, L. casei, L. acidophilus) and B. lactis in mixed cultures present in fermented milks. The invention is novel and competitively advantageous in that it can reliably and simultaneously distinguish and quantify three different species of lactobacilli in relation to one another and other lactic bacteria, such as S. thermophilus, and bifidobacteria present in mixtures in commercial fermented milks. The specificity of the media and the different incubation conditions enable the colonies to be differentiated without the addition of antibiotics that can affect growth and, consequently, quantification. The method has been validated on the basis of specificity, reproducibility, recovery of the tested population and interspecies competition.