Ribosomal ribonucleic acid gene restriction patterns as potential taxonomic tools

Abstract

Deoxyribonucleic acid from 41 different bacterial species (including Gram-negative and Gram-positive species) were cleaved by different restriction endonucleases, electrophoresed in agarose and transferred to nylon filters. The DNA fragments carrying rRNA genes (rDNA) were localized by hybridization with a 32P-labelled Escherichia coli 16 + 23S rRNA probe. A pattern of hybridized fragments was obtained for each DNA tested. Within a bacterial species (defined as a DNA hybridization group), one or several rDNA restriction patterns were observed. When DNA hybridization data were available, strains showing identical patterns were highly related with insignificant divergence. In a species, different patterns corresponded to significant divergence, as evaluated by thermal stability studies of DNA/DNA hybrids. Sets of rDNA restriction fragment sizes might constitute useful data for inclusion in species and type strain descriptions. Such data might later prove useful in identification of bacteria when biochemical characteristics are poor or atypical.