BASE COMPOSITION OF DEOXYRIBONUCLEIC ACID OF SULFATE-REDUCING BACTERIA DEDUCED FROM BUOYANT DENSITY MEASUREMENTS IN CESIUM CHLORIDE

Abstract

The base composition of the deoxyribonucleic acid (DNA) of sulfate-reducing bacteria was calculated from buoyant density measurements in CsCl. The sporulating sulfate-reducing bacteria fell into two groups: Desulfovibrio orientis with a DNA base composition of 42% guanine plus cytosine (G + C), and Clostridium nigrificans with a DNA base composition of 45% G + C. The mesophilic relative of C. nigrificans had a DNA base composition of 46% G + C. Thirty strains of non-sporulating sulfate-reducing bacteria called D. desulfuricans were studied. They fell into three groups as judged by DNA base composition: group-I (11 strains), 60 to 62% G + C; group-II (13 strains), 54 to 56% G + C; and group-III (6 strains), 46 to 47% G + C. These data underline the need for a taxonomic revision of this group of microorganisms.