Publications

4557

A novel anoxygenic photoheterotrophic member of the phylum Acidobacteria , Chloracidobacterium thermophilum strain B sp. nov., was isolated from a cyanobacterial enrichment culture derived from microbial mats associated with Octopus Spring, Yellowstone National Park, WY. C. thermophilum sp. nov. was a Gram-stain-negative rod (diameter, approximately 0.8–1.0 µm; variable length, approximately 2.5 µm), which formed greenish-brown liquid suspension cultures. It was a moderately thermophilic microaerophile and grew in a defined medium at 51 °C (Topt; range 44 to 58 °C) and in the pH range 5.5 to 9.5 (pHopt = ~7.0). The DNA G+C content was 61.3 mol%, and phylogenetic analysis, based on the 16S rRNA sequence, showed that C. thermophilum sp. nov. belongs to subdivision 4 ( Acidobacteriaceae ) of the Acidobacteria . C. thermophilum sp. nov. was unable to synthesize branched-chain amino acids, l-lysine, and vitamin B12, which were required for growth. Although the organism lacked genes/enzymes for autotrophic carbon fixation, bicarbonate was required. Growth was stimulated by other amino acids and 2-oxoglutarate. Cells produced chlorosomes containing a diverse mixture of bacteriochlorophyll (BChl) c derivatives, and additionally, synthesized BChl a P, Chl a PD, and Zn-BChl a′P, which occurred in type-1 homodimeric reaction centres. The carotenoids included echinenone, canthaxanthin, lycopene, γ-carotene and β-carotene. C. thermophilum sp. nov. produced iso-diabolic acid as its major fatty acid and synthesized three hopanoids (diploptene, bacteriohopanetetrol and bacteriohopanetetrol cyclitol ether). Based upon its phenotypic and genotypic properties, the name Chloracidobacterium thermophilum gen. nov., sp. nov. is proposed for this isolate; the type strain is C. thermophilum strain BT (ATCC BAA-2647 = JCM 30199).

ABSTRACT Large sulfur-oxidizing bacteria in the family Beggiatoaceae are important players in the global sulfur cycle. This group contains members of the well-known genera Beggiatoa , Thioploca , and Thiomargarita but also recently identified and relatively unknown candidate taxa, including “ Candidatus Thiopilula” spp. and “ Ca . Thiophysa” spp. We discovered a population of “ Ca . Thiopilula” spp. colonizing cold seeps near Barbados at a ∼4.7-km water depth. The Barbados population consists of spherical cells that are morphologically similar to Thiomargarita spp., with elemental sulfur inclusions and a central vacuole, but have much smaller cell diameters (5 to 40 μm). Metatranscriptomic analysis revealed that when exposed to anoxic sulfidic conditions, Barbados “ Ca . Thiopilula” organisms expressed genes for the oxidation of elemental sulfur and the reduction of nitrogenous compounds, consistent with their vacuolated morphology and intracellular sulfur storage capability. Metatranscriptomic analysis further revealed that anaerobic methane-oxidizing and sulfate-reducing organisms were active in the sediment, which likely provided reduced sulfur substrates for “ Ca . Thiopilula” and other sulfur-oxidizing microorganisms in the community. The novel observations of “ Ca . Thiopilula” and associated organisms reported here expand our knowledge of the globally distributed and ecologically successful Beggiatoaceae group and thus offer insight into the composition and ecology of deep cold seep microbial communities.

ABSTRACT A draft genome sequence of an anaerobic ammonium-oxidizing (anammox) bacterium, “ Candidatus Brocadia sinica,” was determined by pyrosequencing and by screening a fosmid library. A 4.07-Mb genome sequence comprising 3 contigs was assembled, in which 3,912 gene-coding regions, 47 tRNAs, and a single rrn operon were annotated.

ABSTRACT Here, we report the draft genome sequence of “Candidatus Liberibacter asiaticus” strain FL17, isolated from a huanglongbing (HLB)-affected citrus tree in central Florida. The FL17 genome comprised 1,227,253 bp, with a G+C content of 36.5%, 1,175 predicted open reading frames, and 53 RNA genes.

ABSTRACT “Candidatus Methylacidiphilum kamchatkense” strain Kam1 is an aerobic methane-oxidizing thermoacidophilic bacterium belonging to the Verrucomicrobia phylum. It was recovered from an acidic geothermal site in Uzon Caldera, Kamchatka, Russian Federation. Its genome possesses three complete pmoCAB gene clusters encoding particulate methane monooxygenase enzymes and a complete Calvin-Benson-Bassham cycle for carbon assimilation.

ABSTRACT Herein we present the draft genome sequence and annotation of “Candidatus Rickettsia asemboensis” strain NMRCii. “ Ca. Rickettsia asemboensis” is phylogenetically related to but distinct from the flea-borne spotted fever pathogen Rickettsia felis . “ Ca. Rickettsia asemboensis” was initially identified in and subsequently isolated from Ctenocephalides cat and dog fleas from Kenya.