Deoxyribonucleic Acid Base Compositions of Phototrophic Bacteria

Abstract

The deoxyribonucleic acids of 185 strains of phototrophic bacteria (47 strains of Rhodospirillaceae, 104 strains of Chromatiaceae, and 3 4 strains of Chlorobiaceae) have been examined by cesium chloride density gradient centrifugation. The calculated guanine plus cytosine moles percentages are given, and the taxonomic implications are described. Vanyushin and Belozersky (26) provided the first data obtained by chemical analysis on the base composition of the deoxyribonucleic acid (DNA) of a Chromatium sp. and a Chlorobium thiosulfatophilum strain. Marmur and Doty (9) and Schildkraut et al. (21) applied thermal denaturation and CsC 1 buoyant density measurements , respectively, in a survey of the DNA base composition of a larger number of bacteria , including Rhodospirillum rubrum as a phototrophic bacterium. Further data were supplied by Marmur et al. (1 0) for Chromatium sp. and C. thiosulfatophilum, and by Mandel et al. (6) for the genus Chlorobium, Suyama and Gibson (22) and Vanyushin et al. (27). All of these previously reported data were summarized in Table 4. The present study provides the data on 185 strains of the phototrophic (photosynthetic) bacteria, probably representing the majority of strains at present maintained in pure cultures.