TYPES OF LISTERIA-MONOCYTOGENES PREDICTED BY THE POSITIONS OF ECORI CLEAVAGE SITES RELATIVE TO RIBOSOMAL-RNA SEQUENCES

By using taxonomic characters derived from EcoRI restriction endonucle ase digestion of genomic DNA and hybridization with a labeled rRNA ope ron from Escherichia coli, a polymorphic structure of Listeria monocyt ogenes, characterized by fragments with different frequencies of occur rence, was observed. This structure was expanded by creating predicted patterns through a recursive process of observation, expectation, pre diction, and assessment of completeness. This process was applied, in turn, to normalized strain patterns, fragment bands, and positions of EcoRI recognition sites relative to rRNA regions. Analysis of 1346 str ains provided observed patterns, fragment sizes, and their frequencies of occurrence in the patterns. Fragment size statistics led to the cr eation of unobserved combinations of bands, predicted pattern types. T he observed fragment bands revealed positions of EcoRI sites relative to rRNA sequences. Each EcoRI site had a frequency of occurrence, and unobserved fragment sizes were postulated on the basis of knowing the restriction site locations. The result of the recursion process applie d to the components of the strain data was an extended classification with observed and predicted members.