Suppose that at any stage of a statistical experiment a control variable X that affects the distribution of the observed data Y can be used. The distribution of Y depends on some unknown parameter θ, and we consider the classical problem of testing a simple hypothesis H 0 : θ = θ 0 against a simple alternative H 1 : θ = θ 1 allowing the data to be controlled by X, in the following sequential context.The experiment starts with assigning a value X 1 to the control variable and observing Y 1 as a response. After some analysis, we choose another value X 2 for the control variable, and observe Y 2 as a response, etc. It is supposed that the experiment eventually stops, and at that moment a final decision in favour of H 0 or H 1 is to be taken.In this article, our aim is to characterize the structure of optimal sequential procedures, based on this type of data, for testing a simple hypothesis against a simple alternative.Mathematics Subject Classification: 62L10, 62L15, 60G40, 62C99, 93E20

Three strains of facultatively aerobic, moderately thermophilic bacteria were isolated from terrestrial hot springs in Baikal Lake region and Kamchatka (Russia). Cells of the new isolates were cocci reproducing by binary fission. The temperature range for growth was between 20 and 56 6C and the pH range for growth from pH 4.5 to 8.5, with optimal growth at 47-50 6C and pH 7.0-7.5. The organisms were chemoheterotrophs preferring sugars and polysaccharides as growth substrates. 16S rRNA gene sequences of strains 2842, 2813 and 2918Kr were nearly identical (99.7-100 % similarity) and indicated that the strains belonged to the phylum Planctomycetes. The phylogenetically closest cultivated relatives were Algisphaera agarilytica 06SJR6-2 T and Phycisphaera mikurensis FYK2301M01 T with 16S rRNA gene sequence similarity values of 82.4 and 80.3 %, respectively. The novel strains differed from them by higher growth temperature, sensitivity to NaCl concentration above 3.0 % and by their cellular fatty acids profile. On the basis of phylogenetic and physiological data, strains 2842 T , 2813 and 2918Kr represent a novel genus and species for which we propose the name Tepidisphaera mucosa sp. nov. The type strain is 2842 T (5VKM B-2832. We also propose that Tepidisphaera gen. nov. is the type genus of a novel family, Tepidisphaeraceae fam. nov. and a novel order, Tepidisphaerales ord. nov.Thermophilic micro-organisms represent diverse phylogenetic lineages of prokaryotes, including new deep ones (Cole et al., 2013; Kawaichi et al., 2013;Podosokorskaya et al., 2013). Some phylogenetic groups inhabiting thermal environments contain only thermophiles, while others contain organisms with different temperature characteristics (Lebedinsky et al., 2007). Thermophilic representatives are now found even in bacterial phyla previously considered to contain only mesophilic prokaryotes, such as the phylum Acidobacteria (Losey et al., 2013). Another example is the phylum Planctomycetes. Analysis of the diversity and distribution of this group in thermal environments based on environmental molecular data revealed several phylogenetic groups of the phylum Planctomycetes most frequently detected in these habitats (A. Yu. Merkel and others, unpublished results). Several isolates from different terrestrial and subsurface thermal habitats were obtained, enriched and/or isolated in pure cultures and identified as members of the new genus 'Thermogutta' (Slobodkina et al., 2014) which is part of the Pirellula-Blastopirellula-Rhodopirellula cluster. These organisms, together with a representative of the genus 'Thermopirellula' (name not validly published; Liu et al., 2012), are to our knowledge the first thermophilic representatives of the phylum Planctomycetes.Abbreviation: ECL, equivalent chain length.

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An anaerobic, thermophilic bacterium, strain SET IS-9T, was isolated from an Icelandic hot spring. Cells of strain SET IS-9T are short, slightly curved, motile rods. The strain grows chemolithotrophically on CO, producing equimolar quantities of H2 and CO2. It also grows fermentatively on lactate or pyruvate in the presence of yeast extract (0.2 g l−1). Products of pyruvate fermentation are acetate, CO2 and H2. Growth occurs at 50–70 °C, with an optimum at 65 °C, and at pH 5.0–8.0, with an optimum at pH 5.5–6.0. The generation time during chemolithotrophic growth on CO under optimal conditions is 2.0 h. 16S rRNA gene sequence analysis suggested that the organism belongs to the genus Carboxydothermus. On the basis of phenotypic features and phylogenetic analysis, Carboxydothermus islandicus sp. nov. is proposed, with the type strain SET IS-9T ( = DSM 21830T  = VKM B-2561T). An emended description of the genus Carboxydothermus is also given.

Two strains of filamentous, colorless sulfur bacteria were isolated from bacterial fouling in the outflow of hydrogen sulfide-containing waters from a coal mine (Thiothrix sp. Ku-5) and on the seashore of the White Sea (Thiothrix sp. AS). Metagenome-assembled genome (MAG) A52 was obtained from a sulfidic spring in the Volgograd region, Russia. Phylogenetic analysis based on the 16S rRNA gene sequences showed that all genomes represented the genus Thiothrix. Based on their average nucleotide identity and digital DNA-DNA hybridization data these new isolates and the MAG represent three species within the genus Thiothrix with the proposed names Thiothrix subterranea sp. nov. Ku-5T, Thiothrix litoralis sp. nov. AST, and “Candidatus Thiothrix anitrata” sp. nov. A52. The complete genome sequences of Thiothrix fructosivorans QT and Thiothrix unzii A1T were determined. Complete genomes of seven Thiothrix isolates, as well as two MAGs, were used for pangenome analysis. The Thiothrix core genome consisted of 1,355 genes, including ones for the glycolysis, the tricarboxylic acid cycle, the aerobic respiratory chain, and the Calvin cycle of carbon fixation. Genes for dissimilatory oxidation of reduced sulfur compounds, namely the branched SOX system (SoxAXBYZ), direct (soeABC) and indirect (aprAB, sat) pathways of sulfite oxidation, sulfur oxidation complex Dsr (dsrABEFHCEMKLJONR), sulfide oxidation systems SQR (sqrA, sqrF), and FCSD (fccAB) were found in the core genome. Genomes differ in the set of genes for dissimilatory reduction of nitrogen compounds, nitrogen fixation, and the presence of various types of RuBisCO.