Publications

4686

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.

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 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.

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.

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 survey carried out in Georgian vineyards, located in the Khaketi region, in September 2013, showed the presence of vines of the cultivar Chardonnay with typical grapevine yellows (GY) symptoms including leaf discoloration and curling, berry shriveling, and irregular maturation of wood. In the same vineyards, bindweed (Convolvulus arvensis L.) plants showing shoot proliferation and leaf yellowing were found, suggesting the involvement of phytoplasmas in the disease etiology. Total DNA was extracted by a CTAB method from leaf veins of 18 symptomatic and two asymptomatic grapevines, and from four symptomatic and two asymptomatic bindweeds, and analyzed by PCR assays. Moreover, DNA extracted from ‘Candidatus Phytoplasma asteris’ strain SAY (group 16SrI), ‘Ca. P. solani’ strain STOL (group 16SrXII), and ‘Ca. P. ulmi’ strain EY1 (group 16SrV) were used as positive controls. DNA extracted from healthy periwinkle and a reaction mixture without template were employed as negative controls. Nested PCRs targeting the 16S rDNA, carried out using the primer pairs P1/P7 followed by R16F2n/R16R2 (1), produced a band of the expected size (1,250 nt) in all the symptomatic grapevine and bindweed plants, and in the positive controls. No amplification was observed with DNA from asymptomatic plants nor the negative controls. PCR products were sequenced by a commercial sequencing service (Primm, Milan, Italy). The 16S rDNA nucleotide sequences of phytoplasmas identified in all grapevines and in two bindweed samples shared >99.5% sequence identity with ‘Ca. P. solani’ reference strain STOL (GenBank Accession No. AF248959), and carried identical STOL-unique signature sequence and distinguishing sequence blocks (3). Moreover, nucleotide sequences of phytoplasmas identified in the other two bindweed samples shared >99.6% sequence identity with ‘Ca. P. convolvuli’ reference strain BY-S57/11 (JN833705) (2). RFLP and phylogenetic analyses confirmed the affiliation of the phytoplasma strains identified in grapevine and bindweed plants in Georgia to the species ‘Ca. P. solani’ (subgroup 16SrXII-A) and ‘Ca. P. convolvuli’ (subgroup 16SrXII-H). Representative 16S rDNA nucleotide sequences were deposited in NCBI GenBank website with accession nos. KF996535 and KF996536 (‘Ca. P. solani’ from grapevine and bindweed, respectively), and KF996537 (‘Ca. P. convolvuli’). Future studies will focus on investigating the spread and impact of ‘Ca. P. solani’-associated bois noir (BN) in Georgia. In particular, the identification of ‘Ca. P. solani’ in bindweeds suggested the presence of the insect Hyalesthes obsoletus, a polyphagous cixiidae responsible for BN phytoplasma transmission in vineyards in Europe. Accurate surveys and molecular analyses will be performed for identifying the insect vector(s) of the BN associated phytoplasma strains in Georgia. Additional studies will be performed to study the spread and impact of ‘Ca. P. convolvuli,’ identified only in Italy, Germany, Serbia, and Bosnia and Herzegovina (2), throughout the Caucasian countries. References: (1) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) M. Martini et al. Int. J. Syst. Evol. Microbiol. 62:2910, 2013. (3) F. Quaglino et al. Int. J. Syst. Evol. Microbiol. 63:2879, 2013.

A new symptomatology was observed in celery (Apium graveolens) in Villena, Spain in 2008. Symptomatology included an abnormal amount of shoots per plant and curled stems. These vegetative disorders were associated with ‘Candidatus Liberibacter solanacearum’ and not with phytoplasmas. Samples from plant sap were immobilized on membranes based on the spot procedure and tested using a newly developed real-time polymerase chain reaction assay to detect ‘Ca. L. solanacearum’. Then, a test kit was developed and validated by intralaboratory assays with an accuracy of 100%. Bacterial-like cells with typical morphology of ‘Ca. Liberibacter’ were observed using electron microscopy in celery plant tissues. A fifth haplotype of ‘Ca. L. solanacearum’, named E, was identified in celery and in carrot after analyzing partial sequences of 16S and 50S ribosomal RNA genes. From our results, celery (family Apiaceae) can be listed as a new natural host of this emerging bacterium.

ABSTRACT In Europe, human infections with “ Candidatus Neoehrlichia mikurensis” have mainly been restricted to immunocompromised patients. We report here the first cases of asymptomatic “ Ca . Neoehrlichia mikurensis” infection in immunocompetent humans (5/316 [1.6%] were infected). Due to the potential threats of infections with “ Ca . Neoehrlichia mikurensis” in healthy persons to the safety of the blood supply, further study of this phenomenon is required.