DEVELOPMENT OF AN AGAR-MEDIUM (ESCULIN CELLOBIOSE AGAR) FOR THE DETECTION AND ENUMERATION OF LACTOBACILLUS ACIDOPHILUS

Abstract

An agar-medium (Esculin cellobiose agar) is presented which enables the detection and quantitative determination of Lactobacillus acidophilus in dairy products, especially in fermented milk products. For this purpose the ability of L.acidophilus to grow at 40 °C, to ferment cellobiose, and to hydrolyse esculin to esculetine is used. Esculetine forms in combination with Fe (III) ions and olive-green to black complex. For a further differentiation the addition of chlorophenolred was useful. In total 60 strains of lactobacilli, streptococci, and bifidobacteria from 22 species were examined regarding their growth on EC-agar. Only L.acidophilus, L.casei-rhamnosus and L.plantarum could not be differentiated distinctly.