Publications

4467

The two most common haemotropic Mycoplasma of cats, Mycoplasma haemofelis and ‘ Candidatus Mycoplasma haemominutum’ have been identified using molecular techniques in all continents, except Antarctica. We report the first molecular characterization in South America of a dual infection with M haemofelis and ‘ Candidatus Mycoplasma haemominutum’ in three domestic cats. The 16S ribosomal RNA gene was amplified in three anaemic cats in which haemoplasma organisms were seen attached to the erythrocytes in the peripheral blood smear. Bands of the expected size for M haemofelis and ‘ Candidatus Mycoplasma haemominutum’ were observed in all three cats. The 393 bp segment of one of the amplicons had a similarity value of 100% to M haemofelis, whereas the other amplicon, a 192 bp segment, was 100% similar to ‘ Candidatus Mycoplasma haemominutum’. After diagnosis, two cats received blood transfusion and they were all treated with doxycycline. All three cats recovered uneventfully.

A polyphasic study was undertaken to clarify the taxonomic position of endospore-forming strains 433-D9, 433-E17 and 121-X1. BOX-PCR-generated fingerprints indicated that they may be members of a single species. 16S rRNA gene sequence similarity demonstrated that a representative of this group, 433-D9, is affiliated closely with Bacillus arvi DSM 16317T (100 %), Bacillus arenosi DSM 16319T (99.8 %) and Bacillus neidei NRRL BD-87T (97.1 %). Sequence similarities revealed Bacillus pycnus NRRL NRS-1691T and several Kurthia species as the next nearest relatives. DNA–DNA hybridization results showed that strain 433-D9 is a member of B. arvi. Detection of l-Lys–d-Asp-based peptidoglycan in strain 433-D9, B. arvi DSM 16317T and B. arenosi DSM 16319T was in agreement with their close relationship, but differentiated these strains from B. neidei NRRL BD-87T and B. pycnus NRRL NRS-1691T, for which l-Lys–d-Glu was reported. A similar quinone system was detected in strains 433-D9, 433-E17, 121-X1, B. arvi DSM 16317T, B. arenosi DSM 16319T and B. neidei NRRL BD-87T. This system, unusual for bacilli, consisted of the major compound menaquinone MK-8 (69–80 %) and moderate amounts of MK-7 (19–30 %). This observation was in contrast to the predominance of MK-7 of the closest relative B. pycnus NRRL NRS-1691T, as also reported for representatives of the closely related non-endospore-forming genus Kurthia. Strains 433-D9, B. arvi DSM 16317T and B. arenosi DSM 16319T exhibited homogeneous and discriminative polar lipid profiles and fatty acid profiles consisting of major acids i-C15 : 0 and ai-C15 : 0 and moderate amounts of i-C17 : 1 ω10c and i-C17 : 1 I/ai-C17 : 1 B that discriminated them from closely related strains such as B. neidei NRRL BD-87T. On the basis of clear-cut discriminative chemotaxonomic markers, we propose strains 433-D9, 433-E17 and 121-X1, B. arvi DSM 16317T, B. arenosi DSM 16319T and B. neidei NRRL BD-87T to be reclassified within a separate genus. For this new taxon, we propose the name Viridibacillus gen. nov., and we propose the reclassification of Bacillus arvi, Bacillus arenosi and Bacillus neidei as Viridibacillus arvi gen. nov., comb. nov. (the type species of Viridibacillus, with the type strain DSM 16317T =LMG 22165T), Viridibacillus arenosi comb. nov. (type strain DSM 16319T =LMG 22166T) and Viridibacillus neidei comb. nov. (type strain NRRL BD-87T =DSM 15031T =JCM 11077T).

Abstract ‘Candidatus Endobugula sertula,’ the uncultivated γ-proteobacterial symbiont of the marine bryozoan Bugula neritina, synthesizes bryostatins, complex polyketides that render B. neritina larvae unpalatable to predators. Although the symbiosis is well described, little is known about the locations of ‘E. sertula’ or the bryostatins throughout larval settlement, metamorphosis and early development. In this study, we simultaneously localized ‘E. sertula’ and the bryostatins in multiple stages of the B. neritina life cycle, using a novel bryostatin detection method based on its known ability to bind mammalian protein kinase C. Our results suggest that the bryostatins are deposited onto the exterior of B. neritina larvae during embryonic development, persist on the larval surface throughout metamorphosis and are shed prior to cuticle formation. During metamorphosis, ‘E. sertula’ remains adhered to the larval pallial epithelium and is incorporated into the preancestrula cystid tissue layer, which ultimately develops into a bud and gives rise to the next zooid in the colony. Colocalization of bryostatin signal with aggregates of ‘E. sertula’ in buds of ancestrulae suggested new synthesis of bryostatins in ancestrulae. In adult B. neritina colonies, symbiont microcolonies were observed in the funicular cords of rhizoids, which likely result in asexual transmission of ‘E. sertula’ to regenerated colonies. Furthermore, bryostatin signal was detected on the surface of the rhizoids of adult B. neritina colonies. Through simultaneous localization of the bryostatins and the ‘E. sertula,’ we determined how ‘E. sertula’ is transmitted, and identified shifts in bryostatin localization throughout the life cycle of the host B. neritina.

Novel halophilic, alkalithermophilic, Gram-type-positive bacterial strains were isolated from sediment of alkaline, hypersaline lakes of the Wadi An Natrun, Egypt. Cells of strain JW/NM-WN-LFTwere rod-shaped, non-spore-forming and non-motile. Strain JW/NM-WN-LFTgrew (at pH55 °C 9.5) between 35 and 56 °C, with an optimum at 53 °C. The pH55 °Crange for growth was 8.3–10.6, with an optimum at pH55 °C 9.5 and no growth at pH55 °C 8.2 or below, or at pH55 °C 10.8 or above. At the optimum pH and temperature, the strain grew in the Na+range of 3.1–4.9 M (1.5–3.3 M added NaCl) and optimally between 3.3 and 3.9 M Na+(1.7–2.3 M added NaCl). Strain JW/NM-WN-LFTutilized fructose, cellobiose, ribose, trehalose, trimethylamine, pyruvate, Casamino acids, acetate, xylose and peptone as carbon and energy sources. Fumarate (20 mM), S2O32−(20 mM), NO3−(20 mM) and iron(III) citrate (20 mM) were utilized as electron acceptors. During growth on sucrose, the isolate produced acetate and formate as major fermentation products. Main cellular fatty acids were iso-branched 15 : 0, i17 : 0 dimethylacetal and 16 : 0 dimethylacetal. The G+C content of genomic DNA was 40.4 mol% (HPLC). On the basis of genotypic and phenotypic characteristics, it is proposed that strain JW/NM-WN-LFTrepresents a novel genus and species,Natranaerobius thermophilusgen. nov., sp. nov. The type strain is JW/NM-WN-LFT(=DSM 18059T=ATCC BAA-1301T). Based on 16S rRNA gene sequence analysis, the strain forms a novel lineage within the class ‘Clostridia’ and clusters with uncultivated bacteria and unidentified strains retrieved from alkaline, hypersaline environments. The phylogenetic data suggest that the lineage represents a novel family,Natranaerobiaceaefam. nov., and order,Natranaerobialesord. nov.

Summary Recombination is an important process in microbial evolution. Rates of recombination with extracellular DNA matter because models of microbial population structure are profoundly influenced by the degree to which recombination is occurring within the population. Low rates of recombination may be sufficient to ensure the lateral propagation of genes that have a high selective advantage without disrupting the clonal pattern of inheritance for other genes. High rates of recombination potentially can obscure clonal patterns, leading to linkage equilibrium, and give microbial populations a population genetic structure more akin to sexually interbreeding eukaryotic populations. We examined eight loci from nine strains of candidatus Pelagibacter ubique (SAR11), isolated from a single 2L niskin sample of natural seawater, for evidence of genetic recombination between strains. The Shimodaira–Hasegawa test revealed significant phylogenetic incongruence in seven of the genes, indicating that frequent recombination obscures phylogenetic signals from the linear inheritance of genes in this population. Statistical evidence for intragenic recombination was found for six loci. An informative sites matrix showed extensive evidence for a widespread breakdown of linkage disequilibrium. Although the mechanisms of genetic transfer in native SAR11 populations are unknown, we measured recombination rates, ρ , that are much higher than point mutation rates, θ , as a source of genetic diversity in this clade. The eukaryotic model of species sharing a common pool of alleles is more apt for this SAR11 population than a strictly clonal model of inheritance in which allelic diversity is controlled by periodic selection.