International Journal of Systematic and Evolutionary Microbiology

A novel bacterial strain designated HA-01T was isolated from a freshwater terrestrial hot spring located at Hot Springs National Park, Arkansas, USA. Cells were Gram-negative-staining, rod-shaped, aerobic, chemo-organotrophic, oxidase- and catalase-positive, non-spore-forming and motile by means of a single polar flagellum. Growth occurred at 37–60 °C, with an optimum between 45 and 50 °C, and at pH 6.5–8.5, with an optimum between pH 6.5 and 7.0. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the closest relatives of strain HA-01T were Solimonas aquatica NAA-16T (93.8 %), Solimonas flava CW-KD 4T (94.1 %), Solimonas soli DCY12T (93.1 %), Solimonas variicoloris MN28T (94.0 %), Nevskia ramosa Soe1T (91.2 %) and Hydrocarboniphaga effusa AP103T (91.1 %). Major fatty acids consisted of C16 : 0, iso-C16 : 0, C16 : 1ω5c and summed feature 8 (C18 : 1ω9c, C18 : 1ω7c and C18 : 1ω6c). Polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, and the major isoprenoid quinone was Q-8. The DNA G+C content was 64.4 mol%. Based on phylogenetic, phenotypic and chemotaxonomic evidence, it is proposed that strain HA-01T represents a novel species in a new genus for which the name Fontimonas thermophila gen. nov., sp. nov. is proposed. The type strain of the type species is HA-01T ( = DSM 23609T = CCUG 59713T). A new family, Solimonadaceae fam. nov., is also proposed to replace Sinobacteriaceae Zhou et al. 2008.

Plants of Convolvulus arvensis exhibiting symptoms of undersized leaves, shoot proliferation and yellowing, collectively defined as bindweed yellows, were sampled in different regions of Europe and assessed for phytoplasma infection by PCR amplification using phytoplasma universal rRNA operon primer pairs. Positive results were obtained for all diseased plants. RFLP analysis of amplicons comprising the16S rRNA gene alone or the16S rRNA gene and 16-23S intergenic spacer region indicated that the detected phytoplasmas were distinguishable from all other previously described rRNA gene sequences. Analysis of 16S rRNA gene sequences derived from seven selected phytoplasma strains (BY-S57/11, BY-S62/11, BY-I1015, BY-I1016, BY-BH1, BY-BH2 and BY-G) showed that they were nearly identical (99.9–100 % gene sequence similarity) but shared less than 97.5 % similarity with comparable sequences of other phytoplasmas. Thus, BY phytoplasmas represent a new taxon whose closest relatives are stolbur phytoplasma strains and ‘ Candidatus Phytoplasma fragariae ’ with which they share 97.2 % and 97.1 % 16S rRNA gene sequence similarity, respectively. Phylogenetic analysis of 16S rRNA gene sequences confirmed that bindweed yellows phytoplasma strains collectively represent a distinct lineage within the phytoplasma clade and share a common ancestor with previously published or proposed ‘Candidatus Phytoplasma’ taxa within a major branch including aster yellows and stolbur phytoplasmas. On the basis of unique 16S rRNA gene sequences and biological properties that include a single host plant species and a geographical distribution limited to parts of Europe, the bindweed yellows (BY) phytoplasmas represent a coherent but discrete taxon, ‘Candidatus Phytoplasma convolvuli’, with strain BY-S57/11 (GenBank accession no. JN833705) as the reference strain.

A marine, magnetotactic bacterium, designated strain MMS-1T, was isolated from mud and water from a salt marsh in Woods Hole, Massachusetts, USA, after enrichment in defined oxygen-concentration/redox-gradient medium. Strain MMS-1T is an obligate microaerophile capable of chemoorganoheterotrophic and chemolithoautotrophic growth. Optimal growth occurred at pH 7.0 and 24–26 °C. Chemolithoautotrophic growth occurred with thiosulfate as the electron donor and autotrophic carbon fixation was via the Calvin–Benson–Bassham cycle. The G+C content of the DNA of strain MMS-1T was 47.2 mol%. Cells were Gram-negative and morphologically variable, with shapes that ranged from that of a lima bean to fully helical. Cells were motile by means of a single flagellum at each end of the cell (amphitrichous). Regardless of whether grown in liquid or semi-solid cultures, strain MMS-1T displayed only polar magnetotaxis and possessed a single chain of magnetosomes containing elongated octahedral crystals of magnetite, positioned along the long axis of the cell. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MMS-1T belongs to the family Rhodospirillaceae within the Alphaproteobacteria , and is distantly related to species of the genus Magnetospirillum . Strain MMS-1T is therefore considered to represent a novel species of a new genus, for which the name Magnetospira thiophila gen. nov., sp. nov. is proposed. The type strain of Magnetospira thiophila is MMS-1T ( = ATCC BAA-1438T = JCM 17960T).

The taxonomic positions of three thermophilic actinomycetes isolated from arid soil samples were established by using a polyphasic approach. The organisms had chemical and morphological features that were consistent with their classification in the genus Amycolatopsis . 16S rRNA gene sequence data supported the classification of the isolates in the genus Amycolatopsis and showed that they formed distinct branches in the Amycolatopsis methanolica subclade. DNA–DNA relatedness studies between the isolates and their phylogenetic neighbours showed that they belonged to distinct genomic species. The three isolates were readily distinguished from one another and from the type strains of species classified in the A. methanolica subclade based on a combination of phenotypic properties and by genomic fingerprinting. Consequently, it is proposed that the three isolates be classified in the genus Amycolatopsis as representatives of Amycolatopsis granulosa sp. nov. (type strain GY307T = NCIMB 14709T = NRRL B-24844T), Amycolatopsis ruanii sp. nov. (type strain NMG112T = NCIMB 14711T = NRRL B-24848T) and Amycolatopsis thermalba sp. nov. (type strain SF45T = NCIMB 14705T = NRRL B-24845T).

Symptoms of abnormal proliferation of shoots resulting in formation of witches’-broom growths were observed on diseased plants of passion fruit (Passiflora edulis f. flavicarpa Deg.) in Brazil. RFLP analysis of 16S rRNA gene sequences amplified in PCRs containing template DNAs extracted from diseased plants collected in Bonito (Pernambuco) and Viçosa (Minas Gerais) Brazil, indicated that such symptoms were associated with infections by two mutually distinct phytoplasmas. One phytoplasma, PassWB-Br4 from Bonito, represents a new subgroup, 16SrIII-V, in the X-disease phytoplasma group (‘Candidatus Phytoplasma pruni’-related strains). The second phytoplasma, PassWB-Br3 from Viçosa, represents a previously undescribed subgroup in group 16SrVI. Phylogenetic analyses of 16S rRNA gene sequences were consistent with the hypothesis that strain PassWB-Br3 is distinct from previously described ‘Ca. Phytoplasma ’ species. Nucleotide sequence alignments revealed that strain PassWB-Br3 shared less than 97.5 % 16S rRNA gene sequence similarity with previously described ‘Ca. Phytoplasma ’ species. The unique properties of its DNA, in addition to natural host and geographical occurrence, support the recognition of strain PassWB-Br3 as a representative of a novel taxon, ‘Candidatus Phytoplasma sudamericanum’.

The close association between the olive flyBactrocera oleae(Rossi) (Diptera: Tephritidae) and bacteria has been known for more than a century. Recently, the presence of a host-specific, hereditary, unculturable symbiotic bacterium, designated ‘CandidatusErwinia dacicola’, has been described inside the cephalic organ of the fly, called the oesophageal bulb. In the present study, the 16S rRNA gene sequence variability of ‘Ca.E. dacicola’ was examined within and between 26 Italian olive fly populations sampled across areas where olive trees occur in the wild and areas where cultivated olive trees have been introduced through history. The bacterial contents of the oesophageal bulbs of 314 olive flies were analysed and a minimum of 781 bp of the 16S rRNA gene was sequenced. The corresponding host fly genotype was assessed by sequencing a 776 bp portion of the mitochondrial genome. Two ‘Ca. E. dacicola’ haplotypes were found (htA and htB), one being slightly more prevalent than the other (57 %). The two haplotypes did not co-exist in the same individuals, as confirmed by cloning. Interestingly, the olive fly populations of the two main Italian islands, Sicily and Sardinia, appeared to be represented exclusively by the htB and htA haplotypes, respectively, while peninsular populations showed both bacterial haplotypes in different proportions. No significant correlation emerged between the two symbiont haplotypes and the 16 host fly haplotypes observed, suggesting evidence for a mixed model of vertical and horizontal transmission of the symbiont during the fly life cycle.

A novel phytoplasma, designated strain SoyST1c1, associated with a newly emerging disease in soybean (Glycine max), known as soybean stunt (SoyST), was found in 2002 in a soybean plantation in Alajuela Province, Costa Rica. The same phytoplasma, or a very closely related strain, also infected sweet pepper (Capsicum annuum) with purple vein syndrome (SwPPV) and passion fruit vine (Passiflora edulis) with bud proliferation disease (PasFBP) in the same region. Sequence analysis of cloned 16S rRNA gene sequences (GenBank accession nos FJ226068–FJ226073 and HQ225624–HQ225635) indicated that all three affected plants were infected by phytoplasmas that shared <97.5 % sequence similarity with previously described phytoplasmas. The SoyST-causing phytoplasma represents a new taxon, most closely related to phytoplasma group 16SrI and 16SrXII strains. Virtual RFLP analysis indicated that the SoyST-causing phytoplasma and its closely related strains represent a novel 16Sr group, designated 16SrXXXI. Phylogenetic analysis of 16S rRNA gene sequences from the new phytoplasma strains, those previously described as ‘Candidatus Phytoplasma spp.’ and other distinct, as yet unnamed, phytoplasmas indicated that the SoyST-causing phytoplasma represents a distinct lineage within the aster yellows/stolbur branch on the phylogenetic tree. On the basis of its unique 16S rRNA gene sequence and biological properties, strain SoyST1c1 represents a novel taxon, for which the name ‘Candidatus Phytoplasma costaricanum’ is proposed with SoyST1c1 as the reference strain.

An aerobic, saccharolytic, obligately thermophilic, motile, non-spore-forming bacterium, strain T49T, was isolated from geothermally heated soil at Hell’s Gate, Tikitere, New Zealand. On the basis of 16S rRNA gene sequence similarity, T49T is the first representative of a new class in the newly described phylum Armatimonadetes, formerly known as candidate division OP10. Cells of strain T49T stained Gram-negative and were catalase-positive and oxidase-negative. Cells possessed a highly corrugated outer membrane. The major fatty acids were 16 : 0, i17 : 0 and ai17 : 0. The G+C content of the genomic DNA was 54.6 mol%. Strain T49T grew at 50–73 °C with an optimum temperature of 68 °C, and at pH 4.7–5.8 with an optimum growth pH of 5.3. A growth rate of 0.012 h−1 was observed under optimal temperature and pH conditions. The primary respiratory quinone was MK-8. Optimal growth was achieved in the absence of NaCl, although growth was observed at NaCl concentrations as high as 2 % (w/v). Strain T49T was able to utilize mono- and disaccharides such as cellobiose, lactose, mannose and glucose, as well as branched or amorphous polysaccharides such as starch, CM-cellulose, xylan and glycogen, but not highly linear polysaccharides such as crystalline cellulose or cotton. On the basis of its phylogenetic position and phenotypic characteristics, we propose that strain T49T represents a novel bacterial genus and species within the new class Chthonomonadetes classis nov. of the phylum Armatimonadetes. The type strain of Chthonomonas calidirosea gen. nov., sp. nov. is T49T ( = DSM 23976T = ICMP 18418T).

A novel bacterium of the genusPasteuriawas discovered parasitizing bacterivorous nematodes of the genusBursilla, in selected bermudagrass (Cynodon) field plots in Davie, FL, USA. Soil containing this bacterium was sampled and supplied with bi-weekly inoculations of cultured species of the genusBursillain order to build and maintain a source of endospores for continuousin vivoconservation of the bacteria for further study and characterization. 16S rRNA gene sequence similarities supported its congeneric ranking with other members of the genusPasteuriathat have been identified from nematodes and cladocerans. There were, however, no clear sister candidates for this organism, which supported the evidence of endospore ultrastructure and host-range studies, suggesting it belonged to a novel taxon. Because members of the genusPasteuriacannot yet be isolated, definitive type strains could not be maintained; therefore, the name ‘CandidatusPasteuria aldrichii’ is proposed for this organism.

In addition to the grapevine flavescence dorée phytoplasmas, other members of taxonomic group 16SrV phytoplasmas infect grapevines, alders and species of the genera Clematis and Rubus in Europe. In order to investigate which phytoplasmas constitute discrete, species-level taxa, several strains were analysed by comparing their 16S rRNA gene sequences and a set of five housekeeping genes. Whereas 16S rRNA gene sequence similarity values were >97.5 %, the proposed threshold to distinguish two ‘Candidatus Phytoplasma’ taxa, phylogenetic analysis of the combined sequences of the tuf, rplV-rpsC, rplF-rplR, map and uvrB-degV genetic loci showed that two discrete phylogenetic clusters could be clearly distinguished. The first cluster grouped flavescence dorée (FD) phytoplasmas, alder yellows (AldY) phytoplasmas, Clematis (CL) phytoplasmas and the Palatinate grapevine yellows (PGY) phytoplasmas. The second cluster comprised Rubus stunt (RS) phytoplasmas. In addition to the specificity of the insect vector, the Rubus stunt phytoplasma contained specific sequences in the 16S rRNA gene. Hence, the Rubus stunt phytoplasma 16S rRNA gene was sufficiently differentiated to represent a novel putative taxon: ‘Candidatus Phytoplasma rubi’.