Species identification of Streptococcus porcinus by restriction fragment length polymorphism analysis of 16S ribosomal DNA

Streptococcus porcinus reference strains and routine isolates belonging to Lancefield's serogroup E, P, U and V and to various serotypes of serogroup E were examined for their 16S ribosomal DNA fingerprint pattern. Oligonucleotide primers complementary to 16S rRNA genes were used to amplify gene fragments by polymerase chain reaction from genomic DNA. The amplified 1450 bp fragment was subsequently digested with the restriction enzyme BpiI resulting in two fragments with a size of approximately 1250 bp and 200 bp. All 45 S porcinus investigated in the present study could be identified on the basis of this characteristic 16S rDNA fingerprint pattern and clearly differentiated from 16 control strains of various species and serogroups of genus Streptococcus. The present results demonstrate the potential application of 16S rDNA analysis for identification of S porcinus, a species which might express various group- and type-specific antigens.