COMPARISON OF STREPTOCOCCUS-THERMOPHILLUS STRAINS BY PULSE FIELD GEL-ELECTROPHORESIS OF GENOMIC DNA

Pulse field gel electrophoresis (PFGE) was utilised to compare the gen omes of 16 Streptococcus thermophilus cultures from yoghurt, cheese, l aban and dahi after digestion with the restriction endonucleases, SfiI , SmaI and BssHII. PFGE profiles could be used for strain identificati on and were also useful in predicting relatedness of certain strains. Genetic variations between specific morphotypes of a highly proteolyti c culture were not detectable by PFGE in this study. Statistical analy sis of SmaI restriction patterns enabled the clustering of strains int o two groups which corresponded with biochemical properties of the str ains examined and suggested that PFGE profiles could be useful in pred icting biochemical characteristics. (C) 1998 Federation of European Mi crobiological Societies. Published by Elsevier Science B.V. All rights reserved.