General Medicine


Publications (509)

‘Candidatus Erwinia dacicola’, a coevolved symbiotic bacterium of the olive fly Bactrocera oleae (Gmelin)

Citation
Capuzzo et al. (2005). International Journal of Systematic and Evolutionary Microbiology 55 (4)
Names (1)
Ca. Erwinia dacicola
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
The taxonomic identity of the hereditary prokaryotic symbiont of the olive fly Bactrocera oleae (Diptera: Tephritidae) was investigated. In order to avoid superficial microbial contaminants and loosely associated saprophytic biota, flies were surface-sterilized at the larval stage and reared under aseptic conditions until adult emergence. B. oleae flies originating from different geographical locations and collected at different times of the year were tested. Bacterial isolation was undertaken from the cephalic oesophageal bulb, which is known to be a specific site of accumulation for the hosted microsymbionts in the adult insect. Despite evidence of multiplication cycles taking place within the insect, attempts at cultivation of the isolated bacteria ex situ were not productive at any stage, leading to the choice of unculturable status definition. PCR amplification and nucleotide sequencing of the entire 16S rRNA gene consistently yielded a single sequence that displayed marked similarity with enterobacterial lineages, with closest matches (97 %) to Erwinia persicina and Erwinia rhapontici. The novel taxon differs from common intestinal bacterial species of fruit flies and from instances of culturable bacteria previously described in B. oleae raised without sterility precautions, which we also observed as minority occupants or occasional contaminants. The symbiont's identity is also distinct from Pseudomonas savastanoi. In all observations, the numerically dominant inhabitant of the olive fly oesophageal organ was the same unculturable organism, whose presence at later stages was also regularly observed in the midgut. A novel species is proposed, by virtue of its unique properties, under the designation ‘Candidatus Erwinia dacicola’.

Novel chlamydiae in whiteflies and scale insects: endosymbionts ‘Candidatus Fritschea bemisiae’ strain Falk and ‘Candidatus Fritschea eriococci’ strain Elm

Citation
Everett et al. (2005). International Journal of Systematic and Evolutionary Microbiology 55 (4)
Names (2)
“Fritschea eriococci” “Fritschea bemisiae”
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
Bacteria called ‘Fritschea’ are endosymbionts of the plant-feeding whitefly Bemisia tabaci and scale insect Eriococcus spurius. In the gut of B. tabaci, these bacteria live within bacteriocyte cells that are transmitted directly from the parent to oocytes. Whiteflies cause serious economic damage to many agricultural crops; B. tabaci fecundity and host range are less than those of Bemisia argentifolii, possibly due to the presence of this endosymbiont. The B. tabaci endosymbiont has been characterized using electron microscopy and DNA analysis but has not been isolated or propagated outside of insects. The present study compared sequences for 11 endosymbiont genes to genomic data for chlamydial families Parachlamydiaceae, Chlamydiaceae and Simkaniaceae and to 16S rRNA gene signature sequences from 330 chlamydiae. We concluded that it was appropriate to propose ‘Candidatus Fritschea bemisiae’ strain Falk and ‘Candidatus Fritschea eriococci’ strain Elm as members of the family Simkaniaceae in the Chlamydiales.

‘Candidatus Borrelia texasensis’, from the American dog tick Dermacentor variabilis

Citation
Lin et al. (2005). International Journal of Systematic and Evolutionary Microbiology 55 (2)
Names (1)
Ca. Borrelia texasensis
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
TXW-1, a Borrelia strain isolated in March 1998 from an adult male Dermacentor variabilis tick feeding on a coyote from Webb county, Texas, USA, was characterized by using randomly amplified polymorphic DNA (RAPD) analysis, RFLP and sequence analysis of flaB and rrs (16S rRNA gene), DNA–DNA hybridization analysis, SDS-PAGE and Western blotting with mAbs. It shows different banding patterns in RFLP analysis of flaB and forms distinct branches in phylogenetic analysis derived from flaB and rrs genes. It differs from other borreliae based on the banding patterns obtained by RAPD analysis. This strain contains a small, 38-kDa endoflagellar protein. DNA–DNA hybridization experiments revealed that the levels of DNA reassociation between TXW-1 and previously described relapsing fever borreliae were 38·64 % (Borrelia turicatae), 38·40 % (Borrelia parkeri), 7·39 % (Borrelia hermsii) and 18·30 % (Borrelia coriaceae). However, the level of DNA relatedness between B. parkeri and B. turicatae was 78·78 %. Sequence analyses of flaB and rrs genes indicate that the similarities of nucleotide sequences among TXW-1 and B. turicatae or B. parkeri are less than that between B. turicatae and B. parkeri, and that the genetic distances among TXW-1 and B. turicatae or B. parkeri are greater than that between B. turicatae and B. parkeri. TXW-1 lacks an ospC gene. Electron microscope observations showed that this spirochaete had different morphological structures compared to previously described relapsing fever borreliae. All the results obtained from the above-mentioned analyses indicate that TXW-1 is different from other described Borrelia species and that it represents a novel species of Borrelia. We have been unable to revive frozen cultures and so can not meet the requirements of the Bacteriological Code to deposit viable type material at two different culture collections. Therefore we use the Candidatus designation; based on these results, the species ‘Candidatus Borrelia texasensis' is proposed.

‘Candidatus Mycoplasma haematoparvum’, a novel small haemotropic mycoplasma from a dog

Citation
Sykes et al. (2005). International Journal of Systematic and Evolutionary Microbiology 55 (1)
Names (1)
Ca. Mycoplasma haematoparvum
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
A novel small haemoplasma was detected following cytological examination of blood smears from a splenectomized dog with haemic neoplasia. The 16S rRNA and rnpB genes of the organism were partially sequenced and a phylogenetic tree constructed. The organism was most closely related to the small feline haemoplasma, ‘Candidatus Mycoplasma haemominutum’ (94 % 16S rRNA gene nucleotide sequence identity; 75 % rnpB) and was only distantly related to Mycoplasma haemocanis (78 % 16S rRNA gene nucleotide sequence identity; 65 % rnpB). As this organism has not been cultured in vitro, the candidate species name ‘Candidatus Mycoplasma haematoparvum’ is proposed.

‘Candidatus Phytoplasma pini’, a novel taxon from Pinus silvestris and Pinus halepensis

Citation
Schneider et al. (2005). International Journal of Systematic and Evolutionary Microbiology 55 (1)
Names (1)
Ca. Phytoplasma pini
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
Pinus silvestris and Pinus halepensis trees grown in Germany and Spain, respectively, showing abnormal shoot branching, dwarfed needles and other symptoms were examined for the presence of plant-pathogenic mollicutes (phytoplasmas). While phytoplasmas could not be detected unambiguously with microscopical methods, PCR amplification using universal phytoplasma primers yielded positive results. Samples collected from symptomatic and non-symptomatic plant parts of both symptomatic Pinus silvestris and Pinus halepensis trees tested positive. Also, surrounding non-symptomatic trees proved to be phytoplasma-infected. Comparisons revealed that the 16S rRNA gene sequences of the phytoplasmas identified in Pinus silvestris and Pinus halepensis were nearly identical. However, the pine phytoplasma is only distantly related to other phytoplasmas. The closest relatives are members of the palm lethal yellowing and rice yellow dwarf groups and ‘Candidatus Phytoplasma castaneae’, which share between 94·5 and 96·6 % 16S rRNA gene sequence similarity. From these data it can be concluded that the phytoplasmas identified in the two Pinus species represent a coherent but discrete taxon; it is proposed that this taxon be distinguished at putative species level under the name ‘Candidatus Phytoplasma pini’.

‘Candidatus Burkholderia calva’ and ‘Candidatus Burkholderia nigropunctata’ as leaf gall endosymbionts of African Psychotria

Citation
Van Oevelen et al. (2004). International Journal of Systematic and Evolutionary Microbiology 54 (6)
Names (2)
Ca. Burkholderia nigropunctata Ca. Burkholderia calva
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
Phylogenetic 16S rRNA gene analysis was used to assign the bacterial leaf-nodulating endosymbionts of two tropical African Psychotria species to the genus Burkholderia. The microsymbionts of the different Psychotria hosts were recognized as distinct and novel species of Burkholderia on the basis of relatively low intersequence similarities and sufficiently large evolutionary distances when compared with each other and their closest validly named neighbours. The obligate endosymbiotic nature of the bacteria prevented their in vitro cultivation and the deposition of type strains to culture collections. Therefore, the provisional status Candidatus is assigned to the bacterial partners of Psychotria calva and Psychotria nigropunctata, with the proposal of the names ‘Candidatus Burkholderia calva’ and ‘Candidatus Burkholderia nigropunctata’, respectively.

Description of ‘Candidatus Helicobacter heilmannii’ based on DNA sequence analysis of 16S rRNA and urease genes

Citation
O'Rourke et al. (2004). International Journal of Systematic and Evolutionary Microbiology 54 (6)
Names (1)
Ca. Helicobacter heilmannii
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
While Helicobacter pylori is accepted as the major bacterial agent of gastric disease in humans, some patients and many animals are infected with a larger, tightly helical-shaped bacterium previously referred to as ‘Helicobacter heilmannii’ or ‘Gastrospirillum hominis’. Taxonomic classification of these bacteria has been hampered by the inability to cultivate them in vitro and by the inadequate discriminatory power of 16S rRNA gene sequence analysis. This study describes the detection and phylogenetic analysis of 26 different gastrospirillum isolates from humans and animals, which incorporates sequence data based on the 16S rRNA and urease genes. Fifteen gastrospirilla detected in humans, primates and pigs clustered with ‘Candidatus Helicobacter suis’, thus expanding the host range for this organism. By comparison, based on 16S rRNA data, the remaining 11 gastrospirilla could not be differentiated from Helicobacter felis, Helicobacter bizzozeronii and Helicobacter salomonis. However, urease gene sequence analysis allowed for the discrimination of this latter group into four discrete clusters, three of which contained the above recognized species. The fourth cluster contained isolates from human and feline hosts, and should provisionally be considered a unique bacterial species, for which the name ‘Candidatus Helicobacter heilmannii’ is proposed.

Ultrastructure and phylogenetic analysis of ‘Candidatus Neoehrlichia mikurensis' in the family Anaplasmataceae, isolated from wild rats and found in Ixodes ovatus ticks

Citation
Kawahara et al. (2004). International Journal of Systematic and Evolutionary Microbiology 54 (5)
Names (1)
Ca. Neoehrlichia mikurensis
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
A novel bacterium that infects laboratory rats was isolated from wild Rattus norvegicus rats in Japan. Transmission electron microscopy of the spleen tissue revealed small cocci surrounded by an inner membrane and a thin, rippled outer membrane in a membrane-bound inclusion within the cytoplasm of endothelial cells. Phylogenetic analysis of the 16S rRNA gene sequence of the bacterium found in R. norvegicus rats and Ixodes ovatus ticks in Japan revealed that the organism represents a novel clade in the family Anaplasmataceae, which includes the Schotti variant found in Ixodes ricinus ticks in the Netherlands and the Ehrlichia-like Rattus strain found in R. norvegicus rats from China. The novel clade was confirmed by phylogenetic analysis of groESL sequences found in R. norvegicus rats and Ixodes ovatus ticks in Japan. No serological cross-reactivity was detected between this bacterium and members of the genera Anaplasma, Ehrlichia or Neorickettsia in the family Anaplasmataceae. It is proposed that this new cluster of bacteria should be designated ‘Candidatus Neoehrlichia mikurensis’.

Clover proliferation phytoplasma: ‘Candidatus Phytoplasma trifolii’

Citation
Hiruki et al. (2004). International Journal of Systematic and Evolutionary Microbiology 54 (4)
Names (1)
Ca. Phytoplasma trifolii
Subjects
Ecology, Evolution, Behavior and Systematics General Medicine Microbiology
Abstract
Clover proliferation phytoplasma (CPR) is designated as the reference strain for the CP phylogenetic group or subclade, on the basis of molecular analyses of genomic DNA, the 16S rRNA gene and the 16S–23S spacer region. Other strains related to CPR include alfalfa witches'-broom (AWB), brinjal little leaf (BLL), beet leafhopper-transmitted virescence (BLTV), Illinois elm yellows (ILEY), potato witches'-broom (PWB), potato yellows (PY), tomato big bud in California (TBBc) and phytoplasmas from Fragaria multicipita (FM). Phylogenetic analysis of the 16S rRNA gene sequences of BLL, CPR, FM and ILEY, together with sequences from 16 other phytoplasmas that belong to the ash yellows (AshY), jujube witches'-broom (JWB) and elm yellows (EY) groups that were available in GenBank, produced a tree on which these phytoplasmas clearly clustered as a discrete group. Three subgroups have been classified on the basis of sequence homology and the collective RFLP patterns of amplified 16S rRNA genes. AWB, BLTV, PWB and TBBc are assigned to taxonomic subgroup CP-A, FM belongs to subgroup CP-B and BLL and ILEY are assigned to subgroup CP-C. Genetic heterogeneity between different isolates of AWB, CPR and PWB has been observed from heteroduplex mobility assay analysis of amplified 16S rRNA genes and the 16S–23S spacer region. Two unique signature sequences that can be utilized to distinguish the CP group from others were present. On the basis of unique properties of the DNA from clover proliferation phytoplasma, the name ‘Candidatus Phytoplasma trifolii’ is proposed for the CP group.