The Genus Spirillum

Abstract

The morphological, physiological, and nutritional characteristics and the DNA base compositions of 39 strains of Spirillum were determined. A uniform methodology provided a basis for comparison of the strains. The results indicate that the present genus Spirillum should be divided into three genera, with the original name being restricted to obligately microaerophilic freshwater forms having a large cell diameter and a DNA base composition of 36 to 38 mol % guanine + cytosine (G + C). This genus would contain at present only one species, the type species, S. volutans. The generic name Aquaspirillum is proposed for the aerobic, freshwater forms having a DNA base composition of 49 to 65 mol % G + C. Thirteen species are included in this genus, with the type species A. serpens. The following are proposed as type or neotype strains: A. serpens ATCC 12638 (neotype); A. metamorphum ATCC 15280 (type); A. putridiconchylium ATCC 15279 (type); A. gracile ATCC 19624 (type); A. itersonii ATCC 12639 (neotype); A. dispar ATCC 27510 (type); and A. aquaticum ATCC 11330 (type). The generic name Oceanospirillum is proposed for marine forms which do not attack carbohydrates and which possess a DNA base composition of 42 to 48 mol % G + C; five species are included. The following are proposed as type or neotype strains: O. minutulum ATCC 19192 (neotype); O. japonicum ATCC 19191 (neotype); and O. maris ATCC 27509 (type).