Comparison of the adaptive potential of the Arthrobacter oxydans and Acinetobacter lwoffii isolates from permafrost sedimentary rock and the analogous collection strains

A comparative study was conducted on the adaptive mechanisms of the strains Arthrobacter oxydans K14 and Acinetobacter lwoffii EK30A isolated from permafrost subsoil sediments and of those of the analogous collection strains (Ac-1114 Type and BSW-27, respectively). In each pair of the strains compared, the strains differed in terms of (i) growth-related, physiological, and biochemical properties; (ii) resistance to stress factors; (iii) capacity for generation of dormant forms (DFs) under growth arrest conditions, and (iv) intrapopulation production of phase variants. The strains isolated from permafrost displayed a lower growth rate but were more resistant to repeated freezing-thawing treatment than the collection strains. Under the same growth conditions, the permafrost strains formed larger numbers of cystlike anabiotic DFs, extraordinarily small cells, and forms that became nonculturable during long-term storage. Resuscitation of the nonculturable forms resulted in a 2- to-7-fold increase in the percentage of FISH-detectable metabolically active cells. The permafrost strains were also distinguished by increased genome lability. This facilitated their dissociation into intrapopulation variants with phenotypically distinct colonial and morphological properties and different antibiotic resistance. The phenotypic variability was more prominent in Arthrobacter (for which it was not reported previously) than in Acinetobacter. In the populations produced by plating the dormant bacterial forms, the qualitative and quantitative characteristics of the phase variant spectra varied depending on the formation conditions and the composition of the solid media used for the plating. Thus, the permafrost isolates of A. oxydans and Ac. lwoffii were distinguished from their collection analogs by a more manifest adaptive potential including stress resistance, the intensity of DF generation under growth arrest conditions, and increased intrapopulation variability.     

<Emphasis Type="Italic">Thermosulfurimonas marina</Emphasis> sp. nov., an Autotrophic Sulfur-Disproportionating and Nitrate-Reducing Bacterium Isolated from a Shallow-Sea Hydrothermal Vent

A thermophilic, anaerobic, chemolithoautotrophic bacterium (strain SU872^T) was isolated from a shallow-sea hydrothermal vent at Kunashir Island. The cells were motile, gram-negative, oval or rodshaped 0.5?0.6 μm thick and 1.5?2.0 μm long, occurring singly or in pairs. Strain SU872^T grew at 50 to 79°C (optimum at 74°C), pH from 5.0 to 8.0 (optimum at 6.7?7.0), and NaCl concentration of 1.5–4.5%. Strain SU872^T was able to grow by disproportionation of elemental sulfur, thiosulfate, or sulfite, with CO₂/HCO₃^? as the sole carbon source. Growth was enhanced in the presence of ferrihydrite (poorly crystalline Fe(III) oxide) as as a sulfide-scavenging agent. Sulfate was not used as an electron acceptor. Growth also occurred with elemental sulfur, thiosulfate, or sulfite (but not sulfide) as electron donors and nitrate as an electron acceptor, with production of sulfate and ammonium. Analysis of the 16S rRNA gene sequence revealed 97.8% similarity between strain SU872^T and the type strain Thermosulfurimonas dismutans S95^T (phylum Thermodesulfobacteria). According to the results of DNA–DNA hybridization, the similarity of genomic DNA of the strains SU872^T and T. dismutans S95^T was 48%. Based on its phenotypic characteristics and the results of phylogenetic analysis, it is proposed to assign the isolate to a new species of the genus Thermosulfurimonas,—Thermosulfurimonas marina sp. nov., with the type strain SU872^T (=DSM 104922^T, =VKM B-3177^T, =UNIQEM SU872^T).     

Draft genome sequence of the anoxygenic filamentous phototrophic bacterium Oscillochloris trichoides subsp. DG-6

Oscillochloris trichoides is a mesophilic, filamentous, photoautotrophic, nonsulfur, diazotrophic bacterium which is capable of carbon dioxide fixation via the reductive pentose phosphate cycle and possesses no assimilative sulfate reduction. Here, we present the draft genome sequence of Oscillochloris trichoides subsp. DG-6, the type strain of the species, which has permitted the prediction of genes for carbon and nitrogen metabolism and for the light-harvesting apparatus.     

The introduction of the 9α-hydroxy group into androst-4-en-3,17-dione using a new actinobacterium strain

A 9α-hydrolase activity of a new actinobacterium strain identified as Rhodococcus erythropolis based on the analysis of a 16S rRNA gene sequence (1417 nucleotides) towards androst-4-en-3,17-dione (AD) was studied. In the presence of glucose in the medium, this strain completely transformed AD (4–20 g/l) into 9α-hydroxy-AD over 20–48 h. This culture was able to grow and perform AD 9α-hydroxylation at a concentration of dimethyl formamide up to 9%. Crystalline 9α-hydroxy-AD was isolated with a yield of over 90%.     

Tepidibaculum saccharolyticum gen. nov., sp. nov. a moderately thermophilic,anaerobic, spore-forming bacterium isolated from a terrestrial hot spring

Extremophiles - A novel moderately thermophilic, anaerobic bacterium, strain STR9T was isolated from terrestrial hot spring at Uzon Caldera, Kamchatka peninsula, Russia. Cells of strain STR9T were...     

<Emphasis Type="Italic">Halarchaeum solikamskense</Emphasis> sp. nov., a thermotolerant neutrophilic haloarchaeon from the foamy products of flotation enrichment of potassium minerals

Three pigmented strains of halophilic archaea, RS94-RS96, were isolated from acidic foamy products of flotation enrichment of potassium minerals (Silvinit Co., Solikamsk, Russia). The cells were gram-negative, nonmotile, pleomorphic ovoids, 1.0−1.5 × 1.5−2.5 μm. The isolates were chemoorganotrophic, obligately aerobic, and catalase-positive. A range of carbohydrates and organic acids was used, as well as amino acids and peptides. The strains were halophiles and thermotolerant neutrophiles. They grew in the media with 15 to 30% NaCl (optimum at 20–22%) and 0.005–0.7 M Mg²⁺ (0.1–0.2 M), at pH 5.0–8.2 (optimum 7.0–7.2) and 25–55°C (optimum at 35–50°C). The major fatty acids were C_16:0, C_18:1, C_18:0, and C_16:1. The membranes contained carotenoid pigments of the bacterioruberin series and polar lipids, mostly as C₂₀,C₂₀ isoprenoid derivates: phosphatidylglyceromethylphosphate, phosphatidylglycerol, and three unidentified sulfated glycolipids of the S-DGD type. The DNA G+C content was 65.1–66.4 mol %. Phylogenetic analysis based on the 16S rRNA gene sequencing revealed that the thermotolerant neutrophilic isolate RS94 (DNA G+C content of 66.4 mol %) was most closely related to the nonpigmented moderate acidophile Halarchaeum acidiphilum MH1-52-1^T (97.3%). Based on its phenotypic and genotypic characteristics, the organism was classified as a new species of the genus Halarchaeum with the proposed name Halarchaeum solikamskense sp. nov. The type strain is RS94^T (= VKPM B-11282^T).     

<Emphasis Type="Italic">Arhodomonas recens</Emphasis> sp. nov., a halophilic alkane-utilizing hydrogen-oxidizing bacterium from the brines of flotation enrichment of potassium minerals

A halophilic nonpigmented rod-shaped (0.8–1.0 × 2.0–2.5 μm), gram-negative bacterium with a single polar flagellum (strain RS91) was isolated from acidic brines of flotation enrichment of potassium minerals (Silvinit Co., Solikamsk, Russia). The strain grew in the media with 2 to 25% NaCl (optimum at 10–12%), 20–45°C (optimum at 37°C), and pH 5.5–8.5 (optimum 6.5–7.5). It was an aerobe or facultative anaerobe incapable of fermentation. The strain was characterized by the absence of growth on glucose, fructose, and citrate, extensive aerobic growth on n-hexadecane and in the mineral medium with H₂ + O₂ + CO₂ in the gas phase, anaerobic nitrate reduction with acetate or hydrogen (under H₂ + CO₂ + N₂), and variable fatty acid composition. The DNA G+C content was 68.2 mol %. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that while strain RS91 was most closely related to Arhodomonas aquaeolei HA-1^T (98.3%) and Nitrococcus mobilis (98.1%), it was only remotely related to the halophilic phototroph Halorhodospira halophila (90.6%). Based on the combination of its phenotypic and genotypic characteristics, the organism was classified as a new species of the genus Arhodomonas, family Ectothiorhodospiraceae with the proposed name Arhodomonas recens sp. nov. The type strain is RS91^T (= IEGM 796^T = VKPM B-11280^T).     

Benthic phototrophic community from Kiran soda lake,south-eastern Siberia

Phototrophic bacterial mats from Kiran soda lake (south-eastern Siberia) were studied using integrated approach including analysis of the ion composition of water, pigments composition, bacterial diversity and the vertical distribution of phototrophic microorganisms in the mats. Bacterial diversity was investigated using microscopic examination, 16S rRNA gene Illumina sequencing and culturing methods. The mats were formed as a result of decomposition of sedimented planktonic microorganisms, among which cyanobacteria of the genus Arthrospira predominated. Cyanobacteria were the largest part of phototrophs in the mats, but anoxygenic phototrophs were significant fraction. The prevailing species of the anoxygenic phototrophic bacteria are typical for soda lakes. The mats harbored aerobic anoxygenic phototrophic bacteria, purple sulfur and non-sulfur bacteria, as well as new filamentous phototrophic Chloroflexi. New strains of Thiocapsa sp. Kir-1, Ectothiorhodospira sp. Kir-2 and Kir-4, Thiorhodospira sp. Kir-3 and novel phototrophic Chloroflexi bacterium Kir15-3F were isolated and identified.