Use of PCR-based methods for rapid differentiation of Lactobacillus delbrueckii subsp bulgaricus and L-delbrueckii subsp lactis

Two PCR-based methods, specific PCR and randomly amplified polymorphic DNA PCR (RAPD-PCR), were used for rapid and reliable differentiation of Lactoba cillus delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis, PCR with a single combination of primers which targeted the proline iminopeptid ase (pepIP) gene of L. delbrueckii subsp. bulgaricus allowed amplification of genomic fragments specific for the two subspecies when either DNA from a single colony or cells extracted from dairy products were used, A numerica l analysis of the RAPD-PCR patterns obtained with primer M13 gave results t hat were consistent with the results of specific PCR for all strains except L. delbrueckii subsp. delbrueckii LMG 6412(T), which clustered with L. del brueckii subsp. lactis strains. In addition, RAPD-PCR performed with primer 1254 provided highly polymorphic profiles and thus was superior for distin guishing individual L. delbrueckii strains.