Spiroplasma floricola, a New Species Isolated from Surfaces of Flowers of the Tulip Tree, Liriodendron tulipifera L.

Abstract

Spiroplasma strains 23-6 and 27-31 from flowers of Liriodendron tulipifera L. (tulip tree) were indistinguishable from one another but were distinct from Spiroplasma citri and from members of serogroups other than the serogroup which contains S. citri. These two strains shared close to 100% deoxyribonucleic acid homology with one another, but only low homology (≪ 5%) with S. citri and other Spiroplasma strains. The acrylamide gel electrophoretic patterns of the cellular proteins of strains 23-6 and 27-31 appeared to be identical to each other, but they were distinct from the patterns of S. citri and various other strains. On the basis of serological and biochemical characteristics, we propose that strains 23-6 and 27-31 belong to a new species, Spiroplasma floricola, with strain 23-6 (= ATCC 29989) as the type strain. This new species grew well at 30 and 37°C, in contrast to S. citri, which grows poorly if at all at 37°C. During log-phase growth in broth medium, S. floricola cells occurred as motile, helical, cell wallless filaments 0.15 to 0.2μm in diameter and 2 to about 5μm long. Classical “friedegg” Mycoplasma-type colonies were not observed on 1% agar medium. Instead, colonies had granular centers and diffuse borders and contained abundant, motile, helical cells. Growth was stimulated by cholesterol and inhibited by digitonin. Tests for catabolism of glucose, fructose, mannose, and arginine were positive. Tests for phosphatase activity were negative. The guanine-plus-cytosine contents of the deoxyribonucleic acids of strains 23-6 and 27-31 were close to 25 mol%.