Restriction enzyme analysis of PCR-amplified 16S rRNA genes was used to distinguish among clinical isolates of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and Haemophilus paraphrophilus which were originally identified by conventional phenotypic methods. This PCR-based method is a reliable and rapid alternative to conventional methods for identification of these bacterial spe...

Bacteria commonly endow their DNA with an identity mark. When DNA is transferred from one bacterium to another strain of the same species, DNA that lacks the identification mark of the recipient strain is recognized as ‘ foreign’ rather than ‘self ’. Foreign DNA is commonly degraded. The first evidence for this discriminatory process was the demonstration of a barrier, albeit incomplete, to the...