Proposal for Mollicutes as name of the class established for the order Mycoplasmatales

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...

Section: Resultsmentioning

confidence: 99%

Spiroplasma chinense sp. nov. from Flowers of Calystegia hederacea in China

Guo

Chen

Whitcomb

et al. 1990

“…Strain BC-3T and related spiroplasmas from honeybees and other insects have been shown to be members of the Mollicutes (33) and to be referable to the family Spiroplusmataceae (75,76) and to the genus Spiroplasma (71). We propose that these organisms be designated Spiroplasma melliferum sp.…”

Section: Discussionmentioning

confidence: 99%

Spiroplasma melliferum, a New Species from the Honeybee (Apis mellifera)

Clark

Whitcomb

Tully

et al. 1985

102

Twenty-eight strains of spiroplasma subgroup 1-2 isolated from insects and flower surfaces were similar in their serological properties. Strain BC-3T (T = type strain), which was isolated from the honeybee, was chosen as a representative of this cluster and was characterized according to accepted standards. This strain and other strains of the cluster entered the hemocoel of their insect hosts after per 0s acquisition, caused pathology in various tissues, and reduced adult longevity. Growth in SM-1 or M1D medium occurred at 20 to 37"C, with optimum growth at about 32 to 35°C. Cholesterol was required for growth. Glucose, fructose, and other carbohydrates were fermented, and arginine was catabolized. Seventeen strains, including strain BC-3T, reacted with considerable homogeneity in deformation tests and were completely separable from strains of subgroup 1-1 (Spiroplusmu citri) and subgroup 1-3 (corn stunt spiroplasma). A group of five subgroup 1-2 strains showed homogeneity upon one-dimensional polyacrylamide gel electrophoresis of cell proteins. Strain BC-3T was also serologically distinct from subgroups 1-4 through 1-8; from Spiroplusmu JEoricolu, Spiroplusmu upis, and Spiroplasma mirum; and from representative strains of spiroplasma groups I1 and VI through XI. Previously published studies on strain BC-3T and related strains demonstrated that (i) these organisms comprise a unique subgroup of the S. citri complex (group I); (ii) deoxyribonucleic acid-deoxyribonucleic acid homologies between strain BC-3T and strains of other group I subgroups do not exceed 70%; (iii) the patterns of protein sharing among group I strains revealed by two-dimensional polyacrylamide gel electrophoresis support molecular genetic indications of partial relatedness; (iv) the EcoRI restriction endonuclease patterns of deoxyribonucleic acids from strain BC-3T and serologically related strains show close relatedness; (v) sequencing of 5s ribosomal ribonucleic acid suggests some degree of relatedness with all organisms now classified in the Mollicutes; (vi) strain BC-3T is capable of viscotactic and chemotactic responses; (vii) strain BC-3T possesses fibrils that may mediate various types of motility; and (viii) a lytic virus (SpV4) isolated from Spiroplusmu sp. strain B63 (a representative of subgroup 1-2) is morphologically and genomically distinct from other spiroplasma viruses and forms plaques only on lawns of subgroup 1-2 spiroplasmas. Previous work on strain AS 576, another member of subgroup 1-2, demonstrated (i) a viscotactic response, (ii) moderate sensitivity to osmotic environments, (iii) susceptibility to tetracycline and aminoglycoside antibiotics, (iv) growth in a relatively simple, chemically defined medium, (v) nutritional utilization patterns in defined medium, and (vi) a genome molecular weight of lo9. On the basis of our new findings and the previously described properties of strain BC-3T and related subgroup 1-2 strains, we propose that spiroplasma strains with the characteristics described here be classified as a new...

“…From the properties described here and elsewhere (4,30), strain TACT and related acholeplasmas from insect guts have been shown to be members of the class Mollicutes (11). The ability of these organisms to grow in the absence of cholesterol or serum supplements indicates that they belong to the order Acholeplasmatales, family Acholeplasmataceae, and genus Acholeplasma (29).…”

Section: Resultsmentioning

confidence: 99%

Acholeplasma entomophilum sp. nov. from Gut Contents of a Wide Range of Host Insects

Tully

Rose

Carle³

et al. 1988

Eleven sterol-nonkequiring mollicute strains isolated from gut contents of representatives of nine insect genera and two strains isolated from flower surfaces (Bidens sp.) were found to be serologically similar to an insect-derived acholeplasma (strain TACT [T = type strain]) described briefly in an earlier report. Strain TACT, isolated from gut fluids of a tabanid fly (Tabanus catenatus) and shown in earlier studies to belong to the class Mollicutes, lacked a sterol requiremedt for growth and catabolized glucose, but did not hydrolyze arbutin, arginine, or urea. Most strains of the strain TACT cluster grew on serum-free medium alone or on serum-free medium supplemented with a 0.04% Tween 80 fatty acid mixture. The strains grew over a temperature range of 23 to 32°C (optimum, 30°C) but did not grow at 37OC. The guanine-plus-cytosine content of the deoxyribonucleic acid was 30 mol%. Strain TACT was serologically unrelated to the ten previously established species in the genus Acholeplasma and to six other unclassified sterol-nonrequiring strains isolated from plant or insect hosts. The data suggest that this group of new acholeplasmas is widespread in insects and may be disseminated among various plant surfaces during feeding excursions. Strain TAC (= ATCC 43706) is proposed as the type strain of Acholeplasma entomophilum sp. nov.Acholeplasmas (class Mollicutes, order Acholeplasmatales) have become important models in basic studies on wall-less procaryotes, particularly in relation to membrane structure and function, microbial physiology, virus carriage, and procaryote evolution (6,19,20,27,29,35). In contrast to most other mollicutes, acholeplasmas require no cholesterol or serum supplements for growth (12,22,23). In the early history of this group, the ability of acholeplasmas to grow in simple media was frequently invoked in describing them as "saprophytes." This suspected mode of existence was also used to explain their recovery from soil and sewage (see review in reference 26). Later, however, it was established that a variety of serologically and genetically distinct acholeplasmas occurred in association with numerous animal hosts, and it was postulated that the presence of acholeplasmas in soil and sewage came from animal contact (12). Reports of the occurrence of acholeplasmas on, and perhaps in, plants (reviewed in reference 27) began to appear soon after other wall-less procaryotes were found in plant tissues (8). However, since most of these rnollicutes had the features of Acholeplasrna laidlawii, a species originally found in both animal tissues and saprophytic environments, it was not certain what role plants played in the ecology of acholeplasmas (27). In 1979, the recovery of Acholeplasma axanthum, A. oculi, and A . laidlawii from decaying crown tissues of coconut palms aHicted with "lethal yellowing disease" (10) provided substantial evidence for plant involvement in acholeplasma maintenance in nature. These and other Acholeplasrna species also were subsequently recovered from the surfaces of flow...