Revised minimal standards for description of new species of the class Mollicutes (division Tenericutes)

RNA polymerase beta subunit (rpoB) gene and the 16S-23S rRNA intergenic transcribed spacer region (ITS) as complementary molecular markers in addition to the 16S rRNA gene for phylogenetic analysis and identification of the species of the family Mycoplasmataceae

Conventional classification of the species in the family Mycoplasmataceae is mainly based on phenotypic criteria, which are complicated, can be difficult to measure, and have the potential to be hampered by phenotypic deviations among the isolates. The number of biochemical reactions suitable for phenotypic characterization of the Mycoplasmataceae is also very limited and therefore the strategy for the final identification of the Mycoplasmataceae species is based on comparative serological results. However, serological testing of the Mycoplasmataceae species requires a performance panel of hyperimmune sera which contains anti-serum to each known species of the family, a high level of technical expertise, and can only be properly performed by mycoplasma-reference laboratories. In addition, the existence of uncultivated and fastidious Mycoplasmataceae species/isolates in clinical materials significantly complicates, or even makes impossible, the application of conventional bacteriological tests. The analysis of available genetic markers is an additional approach for the primary identification and phylogenetic classification of cultivable species and uncultivable or fastidious organisms in standard microbiological laboratories. The partial nucleotide sequences of the RNA polymerase β-subunit gene (rpoB) and the 16S-23S rRNA intergenic transcribed spacer (ITS) were determined for all known type strains and the available non-type strains of the Mycoplasmataceae species. In addition to the available 16S rRNA gene data, the ITS and rpoB sequences were used to infer phylogenetic relationships among these species and to enable identification of the Mycoplasmataceae isolates to the species level. The comparison of the ITS and rpoB phylogenetic trees with the 16S rRNA reference phylogenetic tree revealed a similar clustering patterns for the Mycoplasmataceae species, with minor discrepancies for a few species that demonstrated higher divergence of their ITS and rpoB in comparison to their neighbor species. Overall, our results demonstrated that the ITS and rpoB gene could be useful complementary phylogenetic markers to infer phylogenetic relationships among the Mycoplasmataceae species and provide useful background information for the choice of appropriate metabolic and serological tests for the final classification of isolates. In summary, three-target sequence analysis, which includes the ITS, rpoB, and 16S rRNA genes, was demonstrated to be a reliable and useful taxonomic tool for the species differentiation within the family Mycoplasmataceae based on their phylogenetic relatedness and pairwise sequence similarities. We believe that this approach might also become a valuable tool for routine analysis and primary identification of new isolates in medical and veterinary microbiological laboratories.

Mycoplasmas hyorhinis in different regions of cuba. diagnosis

M. hyorhinis is considered one of the etiological agents of arthritis in sucking pigs, but recently as seen, some strains can produce pneumonia that could not be distinguished from the mycoplasmosis caused by M. hyopneumoniae. The study was conducted to research the presence of Mycoplasma hyorhinis (M. hyorhinis ) in different regions of the country from exudates of pig lungs with typical EP lesions. Exudates from 280 pig lungs with typical EP lesions were studied using molecular techniques such as PCR, real time PCR and amplification of the 16S-23S rRNA. It was detected that the 66% of the samples studied resulted positive to M. hyorhinis, and the presence of this species was detected in all the provinces. Amplification and studies on the intergenic region 16S-23S of M. hyorhinis rRNA demonstrated the existing variability among strains of a same species. This study is the first report on M. hyorhinis detection in Cuba.

Spiroplasma eriocheiris sp. nov., associated with mortality in the Chinese mitten crab, Eriocheir sinensis

A motile bacterium, designated strain TDA-040725-5T, was isolated from the haemolymph of a Chinese mitten crab, Eriocheir sinensis, with tremor disease. Based on 16S rRNA gene sequence analysis, the strain was phylogenetically distinct from other spiroplasmas but was closely related to Spiroplasma mirum ATCC 29335T. Cells of strain TDA-040725-5T were variable in length and shape, helical and motile, as determined by phase-contrast light microscopy. Examination by electron microscopy revealed wall-less cells delimited by a single membrane. The strain grew in M1D or R-2 liquid media at 20–40 °C, with optimum growth at 30 °C. Doubling time at the optimal temperature was 24 h. The strain catabolized glucose and hydrolysed arginine but did not hydrolyse urea. The DNA G+C content was 29.7±1 mol%. The genome size was ~1.4–1.6 Mbp. Serological analysis, performed using the deformation test, did not reveal any reciprocal titres ≥320, indicating that strain TDA-040725-5T had minimal cross-reactivity to strains of recognized species of the genus Spiroplasma. Based on this evidence, strain TDA-040725-5T ( = CCTCC M 207170T  = DSM 21848T) represents a novel species of the genus Spiroplasma, for which the name Spiroplasma eriocheiris sp. nov. is proposed, belonging to the novel Spiroplasma serological group XLIII.

An expanded collection and refined consensus model of glmS ribozymes

Self-cleaving glmS ribozymes selectively bind glucosamine-6-phosphate (GlcN6P) and use this metabolite as a cofactor to promote self-cleavage by internal phosphoester transfer. Representatives of the glmS ribozyme class are found in Gram-positive bacteria where they reside in the 5' untranslated regions (UTRs) of glmS messenger RNAs that code for the essential enzyme L-glutamine:D-fructose-6-phosphate aminotransferase. By using comparative sequence analyses, we have expanded the number of glmS ribozyme representatives from 160 to 463. All but two glmS ribozymes are present in glmS mRNAs and most exhibit striking uniformity in sequence and structure, which are features that make representatives attractive targets for antibacterial drug development. However, our discovery of rare variants broadens the consensus sequence and structure model. For example, in the Deinococcus-Thermus phylum, several structural variants exist that carry additional stems within the catalytic core and changes to the architecture of core-supporting substructures. These findings reveal that glmS ribozymes have a broader phylogenetic distribution than previously known and suggest that additional rare structural variants may remain to be discovered.

Mycoplasma mucosicanis sp. nov., isolated from the mucosa of dogs

Fourteen Mycoplasma strains were isolated from the oral cavity and genital tract of asymptomatic dogs. Isolates had been preliminarily identified by conventional serological testing as Mycoplasma bovigenitalium, but in 16S-23S rRNA intergenic spacer PCR-RFLP assays the isolates exhibited an RFLP pattern distinct from M. bovigenitalium PG11(T). Analysis of the 16S rRNA gene placed a representative of the isolates (strain 1642(T)) in the M. bovigenitalium subcluster of the Mycoplasma bovis cluster of mycoplasmas, with the highest sequence similarities to Mycoplasma californicum ST-6(T) (96.4 %), M. bovigenitalium PG11(T) (96.3 %) and Mycoplasma phocirhinis 852(T) (96.2 %). 16S rRNA gene sequence similarities almost equidistant from three recognized species and results obtained by sequence analysis of the 16S-23S rRNA intergenic spacer region, polar lipid profiles and serological reactions indicated that this organism represents a novel species of the genus Mycoplasma for which the name Mycoplasma mucosicanis sp. nov. is proposed, with strain 1642(T) ( = ATCC BAA-1895(T)  = DSM 22457(T)) as the type strain.

Spiroplasmas and phytoplasmas: microbes associated with plant hosts

This review will focus on two distinct genera, Spiroplasma and 'Candidatus Phytoplasma,' within the class Mollicutes (which also includes the genus Mycoplasma, a concern for animal-based cell culture). As members of the Mollicutes, both are cell wall-less microbes which have a characteristic small size (1-2 microM in diameter) and small genome size (530 Kb-2220 Kb). These two genera contain microbes which have a dual host cycle in which they can replicate in their leafhopper or psyllid insect vectors as well as in the sieve tubes of their plant hosts. Major distinctions between the two genera are that most spiroplasmas are cultivable in nutrient rich media, possess a very characteristic helical morphology, and are motile, while the phytoplasmas remain recalcitrant to cultivation attempts to date and exhibit a pleiomorphic or filamentous shape. This review article will provide a historical over view of their discovery, a brief review of taxonomical characteristics, diversity, host interactions (with a focus on plant hosts), phylogeny, and current detection and elimination techniques.

Identification and characterization of novel Mycoplasma spp. belonging to the hominis group from griffon vultures

Mycoplasmas are commensals and pathogens of various avian species, and are also regularly found in birds of prey, although their significance to birds' health remains unclear. Here we describe two novel Mycoplasma isolated from the upper respiratory tract of four Eurasian griffon vultures (Gyps fulvus) housed in a wildlife recovery centre in Sardinia (Italy). By sequencing the 16S rRNA gene and the entire 16S/23S intergenic spacer region, the new strains were classified within the Mycoplasma taxonomy at the group and cluster levels, showing that the two isolates fall into the Mycoplasma synoviae and Mycoplasma hominis clusters of the hominis group, respectively. We combined molecular tools and immunoblotting methods in order to further characterize these isolates, and antigenic analyses overall confirmed the molecular findings. Different levels of pathogenicity and prevalence of these strains might have different implications for the conservation and reintroduction of vultures.

Notes on the characterization of prokaryote strains for taxonomic purposes

Taxonomy relies on three key elements: characterization, classification and nomenclature. All three elements are dynamic fields, but each step depends on the one which precedes it. Thus, the nomenclature of a group of organisms depends on the way they are classified, and the classification (among other elements) depends on the information gathered as a result of characterization. While nomenclature is governed by the Bacteriological Code, the classification and characterization of prokaryotes is an area that is not formally regulated and one in which numerous changes have taken place in the last 50 years. The purpose of the present article is to outline the key elements in the way that prokaryotes are characterized, with a view to providing an overview of some of the pitfalls commonly encountered in taxonomic papers.

An Australian environmental survey reveals moderate Spiroplasma biodiversity: characterization of four new serogroups and a continental variant

An environmental survey of tabanid host spiroplasma carriage was undertaken at 10 collection sites in Australia during February 1999. A total of 164 tabanid flies, representing 27 species, were collected and sustainable spiroplasma isolations were made from 48 of the flies. The morphology of the cultured spiroplasmas, as observed in M1D medium under dark-field microscopy, was typical of either (i) Apis group spiroplasmas (relatively thick cells (~150 nm) with six or more turns) or (ii) chrysopicola–syrphidicola–TAAS-1 clade spiroplasmas (narrower, often much shorter cells) serologically related to Spiroplasma serogroup VIII. Repetitive serological analyses, involving successive rounds of dilution cloning and serological reevaluation, identified one serotype referable to the Spiroplasma serogroup VIII strain complex and five putative members of the Apis clade. Apis clade placement for these five groups was verified using 16S rRNA phylogenetic analyses. Among the Apis clade members, one serotype representing 11 isolates was identified as a geographic variant of Spiroplasma turonicum . Spiroplasma turonicum (Tab4C) was originally isolated from a tabanid Haematopoda sp. in France. The other 34 isolates represented four new serogroups (= putative species). The following strains are proposed as representatives of the new serogroups: strain GSU5478 (group XXXIX), strain GSU5490 (group XL), strain GSU5508 (group XLI), and strain GSU5603 (group XLII). In summary, six serogroups were observed from isolations originating from seven distinct sample sites in Australia. Surprisingly, the serotype with the greatest geographical range (five sites from 16°48.9′S to 35°40.0′S) and the greatest host diversity (nine species over three genera) was the geographic variant of S. turonicum, which had only been reported previously in France.

Phylogenetic analysis of the pathogenic bacteria Spiroplasma penaei based on multilocus sequence analysis

A pathogenic Spiroplasma penaei strain was isolated from the hemolymph of moribund Pacific white shrimp, Penaeus vannamei. The shrimp sample originated from a shrimp farm near Cartagena, Colombia, that was suffering from high mortalities in ponds with very low salinity and high temperatures. This new emerging disease in a marine crustacean in the Americas is described as a systemic infection. The multilocus phylogenetic analysis suggests that S. penaei strain has a terrestrial origin. Evolutionary relationship trees, based on five partial DNA sequences of 16S rDNA, 23S rDNA, 5S rDNA, gyrB, rpoB genes and two complete DNA sequences of 16S-23S rDNA and 23S-5S rDNA intergenic spacer region, were reconstructed using the distance-based Neighboring-Joining (NJ) method with Kimura-2-parameter substitution model. The NJ trees based on all DNA sequences investigated in this study positioned S. penaei in the Citri-Poulsonii clade and corroborate the observations by other investigators using the 16S rDNA gene. Pairwise genetic distance calculation between sequences of spiroplasmas showed S. penaei to be closely related to Spiroplasma insolitum and distantly related to Spiroplasma sp. SHRIMP from China.

Rapid polyvalent screening for largescale environmental Spiroplasma surveys

Surface serology is an important determinant in Spiroplasma systematics. Reciprocal antigen/antibody reactions between spiroplasmas and individual antisera delineate the 38 described groups and species. However, reciprocal serology is impractical for large-scale studies. This report describes a successful, streamlined polyvalent screening approach used to examine isolates from an environmental survey.

Culture-independent characterization of bacterial communities associated with the cold-water coral Lophelia pertusa in the northeastern Gulf of Mexico

Bacteria are recognized as an important part of the total biology of shallow-water corals. Studies of shallow-water corals suggest that associated bacteria may benefit the corals by cycling carbon, fixing nitrogen, chelating iron, and producing antibiotics that protect the coral from other microbes. Cold-water or deep-sea corals have a fundamentally different ecology due to their adaptation to cold, dark, high-pressure environments and as such have novel microbiota. The goal of this study was to characterize the microbial associates of Lophelia pertusa in the northeastern Gulf of Mexico. This is the first study to collect the coral samples in individual insulated containers and to preserve coral samples at depth in an effort to minimize thermal shock and evaluate the effects of environmental gradients on the microbial diversity of samples. Molecular analysis of bacterial diversity showed a marked difference between the two study sites, Viosca Knoll 906/862 (VK906/862) and Viosca Knoll 826 (VK826). The bacterial communities from VK826 were dominated by a variety of unknown mycoplasmal members of the Tenericutes and Bacteroidetes, whereas the libraries from VK906/862 were dominated by members of the Proteobacteria. In addition to novel sequences, the 16S rRNA gene clone libraries revealed many bacterial sequences in common between Gulf of Mexico Lophelia corals and Norwegian fjord Lophelia corals, as well as shallow-water corals. Two Lophelia-specific bacterial groups were identified: a cluster of gammaproteobacteria related to sulfide-oxidizing gill symbionts of seep clams and a group of Mycoplasma spp. The presence of these groups in both Gulf and Norwegian Lophelia corals indicates that in spite of the geographic heterogeneity observed in Lophelia-associated bacterial communities, there are Lophelia-specific microbes.