Isolation of an exopolysaccharide-producing Streptococcus thermophilus from Algerian raw cow milk

Lactic acid bacteria (LAB) play a key role in the development of the organoleptic and textural qualities of fermented dairy products. The exopolysaccharides (EPS) produced by LAB are of great technological interest since they improve the rheological characteristics of these products and help reduce syneresis. In the present work, an EPS-producing Streptococcus thermophilus strain was isolated from Algerian raw cow milk. Its identity was confirmed by biochemical and molecular methods. The presence in its genome of a priming glycosyltransferase gene was confirmed by PCR. The strain’s growth and EPS production in milk was analysed and the molar mass of the EPS produced determined by HPLC.