Abstract
In the genomes of various archaebacterial species essentially the some sequence of approximately 30bp is identified repeating over 100 times positioned in several clusters. The periodicity of the repeat is close to 67bp, having a linker of approximately 37bp between neighbouring units. Small differences found between the units are essentially the signatures that specify first the cluster, and second the archaebacterial species to which the units belong. Similar repeats are found in the genomic DNA sequences of eubacterial species, Aquifex aeolicus, and Mycobacterium tuberculosis.
