Differentiation of Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus by polymerase chain reaction

Lactobacillus casei, Lact. paracasei and Lact. rhamnosus form a closely rel ated taxonomic group within the heterofermentative lactobacilli. These thre e species are difficult to differentiate using traditional fermentation pro files. We have developed polymerase chain reaction primers which are specif ic for each of these species based on differences in the V1 region of the 1 6S rRNA gene. Sixty-three Lactobacillus isolates from cheese were identifie d using these primers. The 12 Lact. rhamnosus and 51 Lact. paracasei identi fied in this way were also differentiated using a randomly amplified polymo rphic DNA (RAPD) primer.