Singulisphaera acidiphila gen. nov., sp. nov., a non-filamentous, Isosphaera-like planctomycete from acidic northern wetlands Four novel strains of budding bacteria, designated MOB10 T , PO2, MPL1015 and BG32, were isolated from acidic wetlands of northern Russia. Cells of these four strains were aerobic, non-motile spheres that occurred singly or in shapeless aggregates and attached to surfaces by means of a holdfast material. The isolates were moderately acidophilic, mesophilic organisms capable of growth between pH 4.2 and 7.5 (optimum growth at pH 5.0-6.2) and at temperatures between 4 and 33 6C (optimum growth at 20-26 6C). The strains possessed a complex intracellular membrane system that compartmentalized the cells. The major fatty acids were C 16 : 0 , C 18 : 1 v9c and C 18 : 2 v6c,12c. The major quinone was menaquinone-6 (MK-6). The G+C content of the DNA was 57.8-59.9 mol%. 16S rRNA gene sequence analysis showed that strains MOB10 T , PO2, MPL1015 and BG32 were members of the order Planctomycetales and belonged to a phylogenetic lineage defined by the genus Isosphaera, exhibiting 90 % sequence similarity to the type strain of the thermophilic planctomycete Isosphaera pallida and 95-95.5 % sequence similarity to a taxonomically uncharacterized group of filamentous bacteria from activated sludge, 'Nostocoida limicola' III. However, compared with 'Nostocoida limicola' III and Isosphaera pallida, the new isolates from acidic wetlands were non-filamentous, unpigmented bacteria, which possessed highly distinctive phospholipid fatty acid profiles and were capable of growth and of degrading several biopolymers under acidic, microaerobic and cold conditions. The data suggest that the four isolates should be considered as representing a novel species of a new genus of the order Planctomycetales, for which the name Singulisphaera acidiphila gen. nov., sp. nov. is proposed. The type strain of Singulisphaera acidiphila is MOB10 T (5ATCC BAA-1392 T 5VKM B-2454 T 5DSM 18658 T ).Members of the order Planctomycetales are ubiquitous in a wide range of terrestrial and aquatic environments with diverse conditions (Staley et al., 1992;Schlesner, 1994;Fuerst, 1995Fuerst, , 2004Ward et al., 2006). We recently showed that these micro-organisms are highly abundant in acidic Sphagnum-dominated northern wetlands Kulichevskaya et al., 2006;Ivanova & Dedysh, 2006). Bacterial cells revealed in Sphagnum peat by means of fluorescence in situ hybridization (FISH) with two phylumspecific 16S rRNA-targeted oligonucleotide probes for planctomycetes, PLA46 and PLA886 (Neef et al., 1998), had ellipsoid or spherical morphology. By using an effective combination of a traditional isolation technique with FISH-based monitoring of the enrichment procedure, we succeeded in isolating several peat-inhabiting, acidophilic planctomycetes in pure culture Kulichevskaya et al., 2006). Three of these isolates were Abbreviations: FISH, fluorescence in situ hybridization; PLFA, phospholipid fatty acid.

Schlesneria paludicola gen. nov., sp. nov., the first acidophilic member of the order Planctomycetales, from Sphagnum-dominated boreal wetlands Three strains of budding, ellipsoid-shaped and rosette-forming bacteria were isolated from acidic Sphagnum-dominated boreal wetlands of northern Russia and were designated strains MPL7 T , MOB77 and SB2. The presence of crateriform pits and numerous fibrillar appendages on the cell surface and an unusual spur-like projection on one pole of the cell indicated a planctomycete morphotype. These isolates are moderately acidophilic, mesophilic organisms capable of growth at pH values between 4.2 and 7.5 (with an optimum at pH 5.0-6.2) and at temperatures between 4 and 32 6C (optimum 15-26 6C). The major fatty acids are C 16 : 0 and C 16 : 1 v7c; the major quinone is MK-6. The G+C content of the DNA is 54.4-56.5 mol%. Strains MPL7 T , MOB77 and SB2 possess nearly identical 16S rRNA gene sequences and belong to the planctomycete lineage defined by the genus Planctomyces, being most closely related to Planctomyces limnophilus DSM 3776 T (86.9-87.1 % sequence similarity). However, strain MPL7 T showed only 28 % DNA-DNA hybridization with P. limnophilus DSM 3776T . Compared with currently described members of the genus Planctomyces, the isolates from northern wetlands do not form long and distinctive stalks, have greater tolerance of acidic conditions and low temperatures, are more sensitive to NaCl, lack pigmentation and degrade a wider range of biopolymers. The data therefore suggest that strains MPL7 T , MOB77 and SB2 represent a novel genus and species, for which the name Schlesneria paludicola gen. nov., sp. nov., is proposed. Strain MPL7T (5ATCC BAA-1393 T 5VKM B-2452 T ) is the type strain of Schlesneria paludicola.The order Planctomycetales comprises a remarkable group of budding bacteria that possess highly distinctive cell morphology, peptidoglycan-less cell walls and a unique cell organization (König et al., 1984;Schlesner & Stackebrandt, 1986;Staley et al., 1992;Fuerst, 1995Fuerst, , 2004Fuerst, , 2005Ward et al., 2006). Originally described as freshwater organisms, members of this order were later shown to be ubiquitous in a wide range of aquatic and terrestrial environments with diverse conditions. Despite the reported widespread distribution, the known ecophysiological types of planctomycetes are quite limited. With the only exception of moderately thermophilic Isosphaera pallida (Giovannoni et al., 1987), all taxonomically described planctomycetes are both mesophilic and neutrophilic.Until recently, there has been only one report on the isolation of a planctomycete-like strain from an acidic environment, i.e. peat bog water (pH 4.2) of the Kaltenhofer Moor near Kiel, Germany (Schlesner, 1994). This strain has not been described taxonomically, and no further information except a brief morphologicalAbbreviations: FAME, fatty acid methyl ester; PLFA, phospholipid fatty acid.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain MPL7 T is AM162...

No abstract

Vacuole is a multifunctional compartment central to a large number of functions (storage, catabolism, maintenance of the cell homeostasis) in oxygenic phototrophs including microalgae. Still, microalgal cell vacuole is much less studied than that of higher plants although knowledge of the vacuolar structure and function is essential for understanding physiology of nutrition and stress tolerance of microalgae. Here, we combined the advanced analytical and conventional transmission electron microscopy methods to obtain semi-quantitative, spatially resolved at the subcellular level information on elemental composition of the cell vacuoles in several free-living and symbiotic chlorophytes. We obtained a detailed record of the changes in cell and vacuolar ultrastructure in response to environmental stimuli under diverse conditions. We suggested that the vacuolar inclusions could be divided into responsible for storage of phosphorus (mainly in form of polyphosphate) and those accommodating non-protein nitrogen (presumably polyamine) reserves, respectively.The ultrastructural findings, together with the data on elemental composition of different cell compartments, allowed us to speculate on the role of the vacuolar membrane in the biosynthesis and sequestration of polyphosphate. We also describe the ultrastructural evidence of possible involvement of the tonoplast in the membrane lipid turnover and exchange of energy and metabolites between chloroplasts and mitochondria. These processes might play a significant role in acclimation in different stresses including nitrogen starvation and extremely high level of CO and might also be of importance for microalgal biotechnology. Advantages and limitations of application of analytical electron microscopy to biosamples such as microalgal cells are discussed.

The new strain of filamentous green bacterium strain DG-6 was isolated in pure culture from the spring of Caucuses. The study of this bacterium allows to suggest that it is a member of the familyChloroflexaceae and may be considered asOscillochloris trichoides neotype strain. The description of this green bacterium is given.