Strain CCHT (T = type strain), a helical procaryote that was isolated from floral surfaces of Culystegiu hederuceu (Convolvulaceae) in Jiangsu, People's Republic of China, was found to be a sterol-requiring member of the class Mullicutes. The cells of strain CCHT were small, motile helices that were devoid of a cell wall or periplasmic fibrils. The organism passed through filters with average pore diameters of 300 and 220 nm. Strain CCHT grew rapidly in liquid media having simple compositions, reaching stationary growth phase within 24 h at 30°C. Growth occurred at temperatures ranging from 25 to 37OC. The organism fermented glucose and other sugars with acid production and showed weak arginine hydrolysis. It did not hydrolyze urea. In preliminary electrophoretic analyses, the cell protein patterns of strain CCHT were distinct from those of eight other spiroplasmas commonly found on flowers. Using enzyme-linked immunosorbent assays and antisera to strain CCHT, we found no serological relationship to antigens of the 23 previously recognized spiroplasma groups or species. These distinctions were confirmed by performing reciprocal metabolism inhibition and deformation serological tests, in which we used antigens and antisera to representatives of spiroplasma groups I through XXIII. The base composition (guanine-plus-cytosine content) of the DNA of strain CCHT was about 29.0 mol%. On the basis of these findings, we propose that spiroplasma strain CCH (= ATCC 43960) be designated group XXIV and the type strain of a new species, Spiroplasrnu chinense.Many species of the genus Spiroplasma (class Mollicutes) have been isolated from flower surfaces (2, 8-11, 17, 18, 25-28, 34). Despite the frequency of these isolations, these helical wall-less procaryotes are associated primarily with arthropods and insects (7,34); therefore, their occurrence on flowers probably results from seasonal insect activities. The spiroplasma strains associated with plants and insects have proved to be extraordinarily diverse, and their classification has presented many problems. However, on the basis of their serological and genomic properties, spiroplasmas are now classified into groups or subgroups (25,30,31), which may be converted to species by fulfilling the minimal standards for description of species of Mollicutes (14, 30).In the spring of 1985, flowers of 23 plant species were collected in a field in Jiangsu, People's Republic of China; spiroplasmas were isolated and cultivated from the flower surfaces of 4 of these species (X. D. Ye, M.S. thesis, Nanjing Agricultural University, Nanjing, People's Republic of China, 1987). After purification by cloning procedures, one of the isolates from flowers of Calystegia hederacea (a bindweed and a member of the Convolvulaceae) gave rise to a strain, strain CCHT (T 6 type strain), that proved to be serologically unrelated to spiroplasmas belonging to previously described groups. Subsequently, we accumulated sufficient biological and genomic data to fulfill the minimal requirements for description...

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