A novel species, Methylocella tundrae, is proposed for three methanotrophic strains (T4 T , TCh1 and TY1) isolated from acidic Sphagnum tundra peatlands. These strains are aerobic, Gram-negative, non-motile, dinitrogen-fixing rods that possess a soluble methane monooxygenase and utilize the serine pathway for carbon assimilation. Strains T4

A Gram-negative, aerobic, heterotrophic, non-pigmented, dimorphic prosthecate bacterium was isolated from tundra wetland soil and designated strain Z-0023 T . Cells of this strain had a dimorphic life cycle and developed a non-adhesive stalk at a site not coincident with the centre of the cell pole, a characteristic typical of representatives of the genus Asticcacaulis. A highly distinctive feature of cells of strain Z-0023 T was the presence of a conical, bell-shaped sheath when grown at low temperature. This prosthecate bacterium was a psychrotolerant, moderately acidophilic organism capable of growth between 4 and 28 6C (optimum 15-20 6C) and between pH 4?5 and 8?0 (optimum 5?6-6?0). The major phospholipid fatty acid was 18 : 1v7c and the major phospholipids were phosphatidylglycerols. The G+C content of the DNA was 60?4 mol%. On the basis of 16S rRNA gene sequence similarity, strain Z-0023 T was most closely related to Asticcacaulis biprosthecium (98 % similarity), Asticcacaulis taihuensis (98 %) and Asticcacaulis excentricus (95 %). However, low levels of DNA-DNA relatedness to these organisms and a number of distinctive features of the tundra wetland isolate indicated that it represented a novel species of the genus Asticcacaulis, for which the name Asticcacaulis benevestitus sp. nov. is proposed. The type strain is Z-0023 T (=DSM 16100 T =ATCC BAA-896 T ).

Two metagenome-assembled genomes (MAGs), obtained from laboratory-scale enhanced biological phosphorus removal bioreactors, were analyzed. The values of 16S rRNA gene sequence identity, average nucleotide identity, and average amino acid identity indicated that these genomes, designated as RT and SSD2, represented two novel species within the genus Thiothrix, ‘Candidatus Thiothrix moscowensis’ and ‘Candidatus Thiothrix singaporensis’. A complete set of genes for the tricarboxylic acid cycle and electron transport chain indicates a respiratory type of metabolism. A notable feature of RT and SSD2, as well as other Thiothrix species, is the presence of a flavin adenine dinucleotide (FAD)-dependent malate:quinone oxidoreductase instead of nicotinamide adenine dinucleotide (NAD)-dependent malate dehydrogenase. Both MAGs contained genes for CO2 assimilation through the Calvin–Benson–Bassam cycle; sulfide oxidation (sqr, fccAB), sulfur oxidation (rDsr complex), direct (soeABC) and indirect (aprBA, sat) sulfite oxidation, and the branched Sox pathway (SoxAXBYZ) of thiosulfate oxidation to sulfur and sulfate. All these features indicate a chemoorganoheterotrophic, chemolithoautotrophic, and chemolithoheterotrophic lifestyle. Both MAGs comprise genes for nitrate reductase and NO-reductase, while SSD2 also contains genes for nitrite reductase. The presence of polyphosphate kinase and exopolyphosphatase suggests that RT and SSD2 could accumulate and degrade polyhosphates during the oxic-anoxic growth cycle in the bioreactors, such as typical phosphate-accumulating microorganisms.

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The nitritation-anammox process, which involves partial aerobic oxidation of the ammonium to nitrite and following oxidation of ammonium by nitrite to molecular nitrogen, is an efficient and cost-effective approach for biological nitrogen removal from wastewater. To characterize the microbial communities involved in the nitrogen and carbon cycles in wastewater treatment bioreactors employing this process, we sequenced the metagenome of a sludge sample collected from the lab-scale nitritation-anammox sequencing-batch reactor. At the phylum level, Proteobacteria and Chloroflexi were the most numerous groups. Anammox bacteria belonged to the genus Candidatus Brocadia. The obtained data will help to investigate the taxonomical and functional diversity the microbial communities involved in nitritation-anammox process, and will be used for genome-based analysis of uncultured bacterial lineages. The raw sequencing data is available from the NCBI Sequence Read Archive (SRR9831403) database under the BioProject PRJN0A55627.