Publications

4784

ABSTRACT Here, we present the draft genome of the endosymbiont “ Candidatus Ruthia magnifica” UCD-CM, a member of the phylum Proteobacteria , found from the gills of a deep-sea giant clam, Calyptogena magnifica . The assembly consists of 1,160,249 bp contained in 18 contigs.

ABSTRACT The endosymbiont of Acanthamoeba strain UWC8 is an obligate amoeba endosymbiont belonging to the family of “ Candidatus Midichloriaceae” in Rickettsiales. We report here the complete genome sequence of this bacterium, which should catalyze future studies of amoeba-symbiont interactions.

ABSTRACT “ Candidatus Arthromitus” sp. strain SFB-mouse-NL (SFB, segmented filamentous bacteria) is a commensal bacterium necessary for inducing the postnatal maturation of homeostatic innate and adaptive immune responses in the mouse gut. Here, we report the genome sequence of this bacterium, which sets it apart from earlier sequenced mouse SFB isolates.

Candidatus Liberibacter asiaticus is a fastidious prokaryotic α-proteobacterium that has not been cultured as yet. It is the causative agent of Citrus Huanglongbing (HLB) is a disease that infects citrus plants causing huge losses to the citrus industry. The plants employ a variety of defense mechanisms to combat the pathogen attack which mainly involves the formation of reactive oxygen species (ROS) mainly hydrogen peroxide, peroxynitrite and organic hydroperoxides. The microbe on the other hand has antioxidant proteins that counter the reactive oxygen species. Peroxiredoxin (Prx) which is known to play a crucial role in peroxide detoxification is a super family of one of such antioxidant proteins. In this work, we have determined the crystal structure of Bacterioferritin Comigratory Protein (BCP) that belongs to 1-Cys Prx enzyme having peroxidatic/sulfenic acid cysteine (C-47) but lacks the resolving cysteine. Furthermore, we are investigating structural aspects to gain insight into the binding of different peroxide substrates at the active site. Site directed mutagenesis has been done to introduce the non-conserved resolving cysteine to study its effect on peroxidase activity in both wild type and mutant form. Biochemically, both BCP 1-cys and BCP 2-cys have shown peroxidase activity. DNA protection activity against oxidative damage and cell-line based assays has implicated its protective role towards the hypoxic condition of cells. Hence, the protein becomes a lucrative target for ligands which might be potential antimicrobials.

A mesophilic, neutrophilic and aerobic, ammonia-oxidizing archaeon, strain EN76T, was isolated from garden soil in Vienna (Austria). Cells were irregular cocci with a diameter of 0.6–0.9 µm and possessed archaella and archaeal pili as cell appendages. Electron microscopy also indicated clearly discernible areas of high and low electron density, as well as tubule-like structures. Strain EN76Thad an S-layer with p3 symmetry, so far only reported for members of theSulfolobales. Crenarchaeol was the major core lipid. The organism gained energy by oxidizing ammonia to nitrite aerobically, thereby fixing CO2, but growth depended on the addition of small amounts of organic acids. The optimal growth temperature was 42 °C and the optimal pH was 7.5, with ammonium and pyruvate concentrations of 2.6 and 1 mM, respectively. The genome of strain EN76Thad a DNA G+C content of 52.7 mol%. Phylogenetic analyses of 16S rRNA genes showed that strain EN76Tis affiliated with the recently proposed phylumThaumarchaeota, sharing 85 % 16S rRNA gene sequence identity with the closest cultivated relative ‘CandidatusNitrosopumilus maritimus’ SCM1, a marine ammonia-oxidizing archaeon, and a maximum of 81 % 16S rRNA gene sequence identity with members of the phylaCrenarchaeotaandEuryarchaeotaand any of the other recently proposed phyla (e.g. ‘Korarchaeota’ and ‘Aigarchaeota’). We propose the nameNitrososphaera viennensisgen. nov., sp. nov. to accommodate strain EN76T. The type strain ofNitrososphaera viennensisis strain EN76T( = DSM 26422T = JMC 19564T).Additionally, we propose the familyNitrososphaeraceaefam. nov., the orderNitrososphaeralesord. nov. and the classNitrososphaeriaclassis nov.

Summary The luminous bacterial symbionts of anomalopid flashlight fishes, which appear to be obligately dependent on their hosts for growth, share several evolutionary patterns with unrelated obligate bacteria. However, only one flashlight fish symbiont species has been characterized in detail, and it is therefore not known if the bacteria from other anomalopid species are highly divergent (a pattern common to obligate symbionts). Unlike most obligate symbionts, the bacteria symbiotic with anomalopids are extracellular and spend time outside their hosts in the environment, from which they are thought to colonize new host generations. Environmental acquisition might decrease the likelihood of bacterial divergence between host species. We used phylogenetic analysis to determine the relatedness of symbionts from different anomalopid host species. The symbionts of hosts in the genus P hotoblepharon were resolved as a new species, for which we propose the name ‘ C andidatus   P hotodesmus blepharus’. Furthermore, different genera of anomalopids were found to harbour different species of bacteria, even when the hosts overlapped in geographic range. This finding suggests that the divergence between bacterial species is not the result of geographic isolation. The specificity of symbionts to host genera is consistent with obligate dependence on the host and has implications for symbiont transmission.

Anaplasma platys ( Apl), ‘ Candidatus Mycoplasma haemominutum’ ( CMh), Bartonella henselae ( Bh) and Bartonella koehlerae ( Bk) were confirmed by polymerase chain reaction (PCR) amplification and DNA sequencing in a cat diagnosed with multiple myeloma. Other inconsistently documented hematologic abnormalities included anemia, thrombocytopenia, eosinophilia and hypoglycemia. Persistent Apl infection was confirmed for the first time in a North American cat by sequencing three bacterial genes ( 16S rRNA, p44 and GroEL) in peripheral blood samples collected 100 days apart. Following doxycycline treatment for Apl, multiple myeloma was diagnosed based upon a monoclonal gammopathy and splenic plasmacytosis, and the cat was treated with melphalan, chlorambucil and prednisolone. Apl DNA was not amplified from post-treatment blood samples and the hyperglobulinemia resolved temporarily following chemotherapy. Retrospective PCR analysis of stored DNA extracts identified CMh, Bk and Bh infections. Retrospective PCR for antigen receptor rearrangements (PARR) of splenic aspirates did not confirm B- or T-cell clonality. Co-infection with multiple vector-borne pathogens should be a diagnostic consideration in cats with chronic hypergammaglobulinemia, monoclonal gammopathy and splenic plasmacytosis.

A thermotolerant, Gram-strain-negative, non-spore-forming and strictly aerobic bacterium, designated GU51T, was isolated from Guhai hot spring in Jimsar county, Xinjiang province, north-west China. Each cell of strain GU51Tconsisted of an oval body and two symmetrical long (3–6 µm) prosthecae. The strain moved by polar flagellum. Oxidase and catalase were produced. Strain GU51Tgrew within the ranges of 37–65 °C (optimum 48–50 °C), 0.5–7.5 % (w/v) NaCl (optimum 2–3 %) and pH 6.0–9.0 (optimum pH 7.5). The major respiratory quinone detected was ubiquinone 10 (U-10) and the genomic DNA G+C content was 66.7±0.4 mol%. Major fatty acids (>5 %) were C16 : 0, C18 : 1ω7cand 11-methyl C18 : 1ω7c. The polar lipids consisted of diphosphatidylglycerol, five glycolipids, phosphatidylglycerol and an unknown phospholipid. Phylogenetic analysis showed the closest relatives of strain GU51Twere members of the genusParvularculawith 92.3 % 16S rRNA gene sequence similarity. On the basis of this polyphasic taxonomic characterization, it is suggested that strain GU51Trepresents a novel species of a new genus in the family ‘Parvularculaceae’, for which the nameAmphiplicatus metriothermophilusgen. nov., sp. nov. is proposed. The type strain of the type species is GU51T( = CGMCC 1.12710T = JCM 19779T).

Abstract Amoebae serve as hosts for various intracellular bacteria, including human pathogens. These microbes are able to overcome amoebal defense mechanisms and successfully establish a niche for replication, which is usually the cytoplasm. Here, we report on the discovery of a bacterial symbiont that is located inside the nucleus of its Hartmannella sp. host. This symbiont, tentatively named ‘Candidatus Nucleicultrix amoebiphila’, is only moderately related to known bacteria (∼90% 16S and 23S rRNA sequence similarity) and member of a novel clade of protist symbionts affiliated with the Rickettsiales and Rhodospirillales. Screening of 16S rRNA amplicon data sets revealed a broad distribution of these bacteria in freshwater and soil habitats. ‘Candidatus Nucleicultrix amoebiphila’ traffics within 6 h post infection to the host nucleus. Maximum infection levels are reached after 96–120 h, at which time point the nucleus is pronouncedly enlarged and filled with bacteria. Transmission of the symbionts occurs vertically upon host cell division but may also occur horizontally through host cell lysis. Although we observed no impact on the fitness of the original Hartmannella sp. host, the bacteria are rather lytic for Acanthamoeba castellanii. Intranuclear symbiosis is an exceptional phenomenon, and amoebae represent an ideal model system to further investigate evolution and underlying molecular mechanisms of these unique microbial associations.