Thiorhodococcus mannitoliphagus sp. nov., a new purple sulfur bacterium from the White Sea

A novel purple sulfur bacterium, strain WS(T), was isolated from a microbial mat from an estuary of the White Sea. Individual cells are coccoid shaped, motile by flagella and do not contain gas vesicles. The mean cell diameter is 1.85 mum (range 1.5-2.0 mum). Cell suspensions exhibit a purple-violet colour. They contain bacteriochlorophyll a and carotenoids of the rhodopinal series as photosynthetic pigments. The novel bacterium is an anoxygenic photoautotroph, using sulfide, thiosulfate, sulfite and elemental sulfur as electron donors for photosynthesis and is capable of photoassimilating several organic carbon sources in the presence of carbonate and a reduced sulfur source (sulfide and/or thiosulfate). Sulfur globules, formed during oxidation of sulfide, are stored transiently inside the cells. Optimal salinity and pH for growth are at 0.5-2.0 % NaCl and pH 7.0-7.5. The DNA base composition of strain WS(T) is 61.8 mol% G+C. 16S rRNA gene sequence analysis showed that the new isolate belongs to the genus Thiorhodococcus, with Thiorhodococcus minor CE2203(T) as the nearest relative (sequence similarity of 97.3 %). Several distinct differences from described species necessitate the description of a novel species. Thiorhodococcus mannitoliphagus sp. nov. is the proposed name, with strain WS(T) (=ATCC BAA-1228(T)=VKM B-2393(T)) as the type strain

Lamprobacter

Lam' pro.bac' ter. Gr. adj. lampros bright, brilliant; M.L. masc. n. bacter rod; M.L. masc. n. Lamprobacter brilliant rod. Proteobacteria / Gammaproteobacteria / Chromatiales / Chromatiaceae / Lamprobacter Cells are rod shaped or ovoid, 2.0–2.5 × 4–5 µm, multiply by binary fission, do not form aggregates. Gas vesicles formed in cell periphery or in the entire cytoplasm. Motile by flagella during certain stages of development. Motile cells normally devoid of gas vesicles. Gram negative, belong to the Gammaproteobacteria, and contain internal photosynthetic membranes of vesicular type with bacteriochlorophyll a and carotenoids as photosynthetic pigments. The mol% G + C of the DNA is: 60–64. Type species: Lamprobacter modestohalophilus Gorlenko, Krasil' nikova, Kikina and Tatarinova 1988, 220 (Effective publication: Gorlenko, Krasil' nikova, Kikina and Tatarinova 1974, 765.

Thiorhodospira

Thi' o.rho' do.spi' ra. Gr. n. thios sulfur; Gr. n. rhodon the rose; Gr. n. spira spiral; M.L. fem. n. Thiorhodospira the spiral rose with sulfur. Proteobacteria / Gammaproteobacteria / Chromatiales / Ectothiorhodospiraceae / Thiorhodospira Cells vibrioid or spiral-shaped, motile by means of a monopolar flagellar tuft, multiplies by binary fission. Gram-negative and belong to the Gammaproteobacteria. Internal photosynthetic membranes are parallel lamellae piercing the cytoplasm lengthwise or underlying the cytoplasmic membrane. Photosynthetic pigments are bacteriochlorophyll a and carotenoids. The mol% G + C of the DNA is: 56.0–57.4 (Tm ). Type species: Thiorhodospira sibirica Bryantseva, Gorlenko, Kompantseva, Imhoff, Süling and Mityushina 1999b, 700

Genome of Lamprobacter modestohalophilus ShN Lb 02, a moderate halophilic photosynthetic purple bacterium of the Chromatiaceae family

The genome sequence of the moderately halophilic Lamprobacter modestohalophilus ShNLb02 was compared to those of other Lamprobacter and Halochromatium species. It revealed an average nucleotide identity of 94% to Lpb. modestohalophilus DSM 25653 and of 89.7% to Halochromatium roseum DSM 18859, underscoring their close phylogenetic relationship

Ectothiorhodospira lacustris sp. nov., a New Purple Sulfur Bacterium from Low-Mineralized Soda Lakes That Contains a Unique Pathway for Nitric Oxide Reduction

Several strains of a Gram-negative, anaerobic photoautotrophic, motile, rod-shaped bacterium, designated as B14B, A-7R, and A-7Y were isolated from biofilms of low-mineralized soda lakes in central Mongolia and Russia (southeast Siberia). They had lamellar stacks as photosynthetic structures and bacteriochlorophyll a as the major photosynthetic pigment. The strains were found to grow at 25–35 °C, pH 7.5–10.2 (optimum, pH 9.0), and with 0–8% (w/v) NaCl (optimum, 0%). In the presence of sulfide and bicarbonate, acetate, butyrate, yeast extract, lactate, malate, pyruvate, succinate, and fumarate promoted growth. The DNA G + C content was 62.9–63.0 mol%. While the 16S rRNA gene sequences confirmed that the new strains belonged to the genus Ectothiorhodospira of the Ectothiorhodospiraceae, comparison of the genome nucleotide sequences of strains B14B, A-7R, and A-7Y revealed that the new isolates were remote from all described Ectothiorhodospira species both in dDDH (19.7–38.8%) and in ANI (75.0–89.4%). The new strains are also genetically differentiated by the presence of a nitric oxide reduction pathway that is lacking from all other Ectiothiorhodospiraceae. We propose to assign the isolates to the new species, Ectothiorhodospira lacustris sp. nov., with the type strain B14BT (=DSM 116064T = KCTC 25542T = UQM 41491T)

Cryo-Electron Tomography Reveals the Complex Ultrastructural Organization of Multicellular Filamentous Chloroflexota (Chloroflexi) Bacteria

The cell biology of Chloroflexota is poorly studied. We applied cryo-focused ion beam milling and cryo-electron tomography to study the ultrastructural organization of thermophilic Roseiflexus castenholzii and Chloroflexus aggregans, and mesophilic “Ca. Viridilinea mediisalina.” These species represent the three main lineages within a group of multicellular filamentous anoxygenic phototrophic Chloroflexota bacteria belonging to the Chloroflexales order. We found surprising structural complexity in the Chloroflexales. As with filamentous cyanobacteria, cells of C. aggregans and “Ca. Viridilinea mediisalina” share the outer membrane-like layers of their intricate multilayer cell envelope. Additionally, cells of R. castenholzii and “Ca. Viridilinea mediisalina” are connected by septal channels that resemble cyanobacterial septal junctions. All three strains possess long pili anchored close to cell-to-cell junctions, a morphological feature comparable to that observed in cyanobacteria. The cytoplasm of the Chloroflexales bacteria is crowded with intracellular organelles such as different types of storage granules, membrane vesicles, chlorosomes, gas vesicles, chemoreceptor-like arrays, and cytoplasmic filaments. We observed a higher level of complexity in the mesophilic strain compared to the thermophilic strains with regards to the composition of intracellular bodies and the organization of the cell envelope. The ultrastructural details that we describe in these Chloroflexales bacteria will motivate further cell biological studies, given that the function and evolution of the many discovered morphological traits remain enigmatic in this diverse and widespread bacterial group

Draft genome sequences of ‘Candidatus Chloroploca asiatica’ and ‘Candidatus Viridilinea mediisalina’, candidate representatives of the Chloroflexales order: phylogenetic and taxonomic implications

Abstract ‘Candidatus Chloroploca asiatica’ B7–9 and ‘Candidatus Viridilinea mediisalina’ Kir15-3F are mesophilic filamentous anoxygenic phototrophic bacteria from alkaline aquatic environments. Both bacteria became available in the last few years and only in stable enrichment culture. In this study, we report the draft genomic sequences of ‘Ca. Chloroploca asiatica’ B7–9 and ‘Ca. Viridilinea mediisalina’ Kir15-3F, which were assembled from metagenomes of their cultures with a fold coverage 86.3× and 163.8×, respectively. The B7–9 (5.8 Mb) and the Kir15-3F (5.6 Mb) draft genome harbors 4818 and 4595 predicted protein-coding genes, respectively. In this article, we analyzed the phylogeny of representatives of the Chloroflexineae suborder in view of the appearance of new genomic data. These data were used for the revision of earlier published group-specific conserved signature indels and for searching for novel signatures for taxons in the Chloroflexineae suborder

Microbial activity in Martian analog soils after ionizing radiation: implications for the preservation of subsurface life on Mars

At present, the surface of Mars is affected by a set of factors that can prevent the survival of Earth-like life. However, the modern concept of the evolution of the planet assumes the existence more favorable for life climate in the past. If in the past on Mars had formed a biosphere, similar to the one that originated in the early Earth, it is supposed that it is preserved till now in anabiotic state in the bowels of the planet, like microbial communities inhabiting the ancient permafrost of Arctic and Antarctic. In the conditions of modern Martian regolith, this relic life seems to be deprived of the possibility of damage reparation (or these processes occur on a geological time scale), and ionizing radiation should be considered the main factor inhibiting such anabiotic life. In the present study, we studied soil samples, selected in two different extreme habitats of the Earth: ancient permafrost from the Dry Valleys of Antarctica and Xerosol soil from the mountain desert in Morocco, gamma-irradiated with 40 kGy dose at low pressure (1 Torr) and low temperature (−50 °C). Microbial communities inhabiting these samples showed in situ high resistance to the applied effects, retained high number of viable cells, metabolic activity, and high biodiversity. Based on the results, it is assumed that the putative biosphere could be preserved in the dormant state for at least 500 thousand years and 8 million years in the surface layer of Mars regolith and at 5 m depth, respectively, at the current level of ionizing radiation intensity