Differentiation of Lactobacillus delbrueckii subspecies by ribotyping and amplified ribosomal DNA restriction analysis (ARDRA)

Aims: To differentiate the subspecies of Lactobacillus delbrueckii, subsp, delbrueckii, subsp, lactis and subsp, bulgaricus. Methods and Results: Amplified ribosomal DNA restriction analysis (ARDRA) a nd ribotyping were applied to over 30 strains. Both methods analyse the rib osomal genes which carry useful information about the evolutionary and taxo nomic relationship among bacteria. The methods proved to be reliable and hi ghly reproducible. ARDRA was applied to 16S rDNA, 23S rDNA and the IGS regi on, thus covering the whole rrn operon with eight restriction enzymes. Only EcoRI differentiated Lact. delbrueckii subsp, bulgaricus from Lact. delbru eckii subsp, delbrueckii/Lact. delbrueckii subsp. lactis, which confirmed t he finding of other authors. Ribotyping with different enzymes under precis ely optimized conditions revealed a high level of strain polymorphism. Only ribotyping with EcoRI allowed differentiation of the three subspecies on t he basis of typical hybridization patterns. Conclusions: The successful differentiation of the three subspecies of Lact , delbrueckii by EcoRI ribotyping offers a new possibility for precise iden tification and differentiation of strains and new isolates. Significance and Impact of the Study: Both methods could be used for differ entiation of Lact. delbrueckii subspecies.