Desulfosporosinus paludis sp. nov., an acidotolerant sulphate-reducing bacterium isolated from moderately acidic fen soil

An obligately anaerobic, spore-forming sulphate-reducing bacterium, strain SB140T, was isolated from a long-term continuous enrichment culture that was inoculated with peat soil from an acidic fen. Cells were immotile, slightly curved rods that stained Gram-negative. The optimum temperature for growth was 28 °C. Strain SB140T grew at pH 4.0-7.5 with an optimum pH of 6.0-7.0 using various electron donors and electron acceptors. Yeast extract, sugars, alcohols and organic acids were used as electron donors for sulphate reduction. SB140T additionally used elemental sulphur and nitrate as electron acceptors but not sulphite, thiosulphate or iron(III) provided as ferrihydrite and fumarate. The 16S rRNA gene sequence placed strain SB140T in the genus Desulfosporosinus of the phylum Bacillota. The predominant cellular fatty acids were iso-C15 : 0 (52.6%) and 5,7 C15 : 2 (19.9%). The draft genome of SB140T (5.42 Mbp in size) shared 77.4% average nucleotide identity with the closest cultured relatives Desulfosporosinus acididurans M1T and Desulfosporosinus acidiphilus SJ4T. On the basis of phenotypic, phylogenetic and genomic characteristics, SB140T was identified as a novel species within the genus Desulfosporosinus, for which we propose the name Desulfosporosinus paludis sp. nov. The type strain is SB140T (=DSM 117342T=JCM 39521T).

Tanning wastewater restructured nitrogen-transforming bacteria communities and promoted N2O emissions in receiving river riparian sediments

Physicochemical and toxicological characterization of leather tanning wastewater has been widely documented. However, few reports have examined the response of denitrification N2 and N2O emissions in riparian sediments of tannery wastewater-receiving rivers. In this study, 15N-nitrate labeling was used to reveal the effects of tanning wastewater on denitrification N2 and N2O emission in a wastewater-receiving river (the old Mang River, OMR). OMR riparian sediments were highly polluted with total organic carbon (93.39 mg/kg), total nitrogen (5.00 g/kg) and heavy metals; specifically, Cr, Zn, Cd, and Pb were found at concentrations 47.3, 5.8, 1.6, 4.3, and 2.8 times that in a nearby parallel river without tanning wastewater input (the new Mang River, NMR), respectively. The denitrification N2 emission rates (0.0015 nmol N · g-1 h-1) of OMR riparian sediments were significantly reduced by 2.5 times compared with those from the NMR (p < 0.05), but the N2O emission rates (0.31 nmol N · g-1 h-1) were significantly increased (4.1 times, p < 0.05). Although the dominant nitrogen-transforming bacteria phylum was Proteobacteria in the riparian sediments of both rivers, 11 nitrogen-transforming bacteria genera in the OMR were found to be significantly enriched; five of these were related to pollutant degradation based on linear discriminant analysis (LDA >3). The average activity of the electron transport system in the OMR was 6.3 times lower than that of the NMR (p < 0.05). Among pollution factors, heavy metal complex pollution was the dominant factor driving variations in N2O emissions, microbial community structure, and electron transport system activity. These results provide a new understanding and reference for the treatment of tanning wastewater-receiving rivers.

Peiella sedimenti gen. nov., sp. nov., a novel taxon within the family Caulobacteraceae isolated from sediment of a river

A Gram-stain-negative bacterium, designated XZ-24T, was isolated from sediment of a river in Mianyang city, Sichuan province, PR China. Cells (1.0-2.0 µm long and 0.4-0.5 µm in width) were strictly aerobic, non-spore-forming, rod shaped, prosthecate and motile by means of a polar flagellum. Growth occurred at 10-37 °C (optimum, 30 °C), at pH 5.0-9.0 (optimum pH 7.0) and with 0-3.0 % (w/v) NaCl (optimum 1.0 % NaCl). The results of phylogenetic analysis based on genomes and 16S rRNA gene sequences indicated that XZ-24T formed a distinct phyletic branch within the family Caulobacteraceae and was most closely related to members of the genera Brevundimonas, Caulobacter and Phenylobacterium with 95.3-96.5 % 16S rRNA gene sequence similarities. The average amino acid identities (AAI) between XZ-24T and species of the family Caulobacteraceae were 47.0-64.5 %, which were below the genus boundary (70 %). The predominant cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C16 : 0, C18 : 1ω7c 11-methyl and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), the isoprenoid quinone was Q-10, and the major polar lipids were 1,2-di-O-acyl-3-O-α-d-glucopyranuronosyl glycerol; 1,2-di-O-acyl-3-O-[d-glucopyranosyl-(1→4)-α-d glucopyranuronosyl] glycerol and phosphatidylglycerol. The genome size of XZ-24T was 2.64 Mb with a DNA G+C content of 68.9 %. On the basis of the evidence presented in this study, strain XZ-24T represents a novel species of a novel genus in the family Caulobacteraceae, for which the name Peiella sedimenti gen. nov., sp. nov. (Type strain XZ-24T=CCTCC AB 20 23 094T=KCTC 8038T) is proposed.

Aurantibacillus circumpalustris gen. nov., sp. nov., the first characterized representative of the Bacteroidota candidate family env.OPS 17 and proposal of Aurantibacillaceae fam. nov

16S rRNA sequence types associated with the candidate family env.OPS 17 have been reported from various environments, but no representatives have been characterized and validly named. Bacteria of env.OPS 17 are affiliated with the order Sphingobacteriales and were first detected more than two decades ago in the vicinity of a thermal spring in Yellowstone National Park. Strain Swamp196T, isolated from the soil surrounding a swamp in Northern Germany, is the first characterized representative of candidate family env.OPS 17. Cells of strain Swamp196T are rod-shaped, non-motile, non-spore-forming, non-capsulated and stain Gram-negative. Colonies are small and orange-coloured. The strain is mesophilic and grows under aerobic or microaerophilic conditions. It grows chemo-organotrophically over a narrow range of pH and exclusively on proteinaceous substrates. The major cellular fatty acids are iso-C15 : 0, iso-C15 : 1  ω10c, C18 : 1  ω9c and C16 : 1  ω7c and the major polar lipids are two unidentified aminophospholipids, one unidentified aminolipid and one unidentified lipid. The predominant respiratory quinone is MK-7. The DNA G+C content of genomic DNA is 35.5 mol%. Strain Swamp196T is related to Pedobacter cryophilus AR-3-17T, Arcticibacter pallidicorallinus Hh36T and Pedobacter daechungensis Dae 13T with 16S rRNA gene sequence similarity of 84.1, 83.8 and 83.5 %, respectively. Based on our phenotypic, genomic and phylogenetic analysis, we propose the novel species Aurantibacillus circumpalustris sp. nov (type strain Swamp196T=DSM 105849T=CECT 30420T) of the novel genus Aurantibacillus gen. nov. and the novel family Aurantibacillaceae fam. nov.

Characterization of a bloom-associated alphaproteobacterial lineage, 'Candidatus Phycosocius': insights into freshwater algal-bacterial interactions

Marine bacterial lineages associated with algal blooms, such as the Roseobacter clade, have been well characterized in ecological and genomic contexts, yet such lineages have rarely been explored in freshwater blooms. This study performed phenotypic and genomic analyses of an alphaproteobacterial lineage 'Candidatus Phycosocius' (denoted the CaP clade), one of the few lineages ubiquitously associated with freshwater algal blooms, and described a novel species: 'Ca. Phycosocius spiralis.' Phylogenomic analyses indicated that the CaP clade is a deeply branching lineage in the Caulobacterales. Pangenome analyses revealed characteristic features of the CaP clade: aerobic anoxygenic photosynthesis and essential vitamin B auxotrophy. Genome size varies widely among members of the CaP clade (2.5-3.7 Mb), likely a result of independent genome reductions at each lineage. This includes a loss of tight adherence pilus genes (tad) in 'Ca. P. spiralis' that may reflect its adoption of a unique spiral cell shape and corkscrew-like burrowing activity at the algal surface. Notably, quorum sensing (QS) proteins showed incongruent phylogenies, suggesting that horizontal transfers of QS genes and QS-involved interactions with specific algal partners might drive CaP clade diversification. This study elucidates the ecophysiology and evolution of proteobacteria associated with freshwater algal blooms.

Capillimicrobium parvum gen. nov., sp. nov., a novel representative of Capillimicrobiaceae fam. nov. within the order Solirubrobacterales, isolated from a grassland soil

The order Solirubrobacterales is a deep-branching lineage within the phylum Actinomycetota . Most representatives have been isolated from terrestrial environments. A strain isolated from a grassland soil was found to be affiliated with this order and therefore characterized by a polyphasic approach. Cells of strain 0166_1T are Gram-positive, short rods, non-motile, non-spore-forming and divide by binary fission. A surface layer with protrusions covers the majority of the cells. Strain 0166_1T grows optimally around neutral to slightly alkaline pH (pH 7.1–7.9) and at temperatures between 24–36 °C in SSE/HD 1 : 10 medium. It grows optimally with 0–0.5% NaCl (w/v) but can withstand concentrations up to 5 %. The major fatty acids are C18 : 1 ω9c, C16 : 1  ω7c, C17 : 0 cyclo ω7c, C18 : 1  ω7c methyl and C19 : 0 cyclo ω9c. The major polar lipids are diphosphatidylglycerol, two unidentified phospholipids and one unidentified glycolipid. MK-7(H4) and MK-7(H2) are the predominant respiratory quinones. meso-2,6-Diaminopimelic acid is the diagnostic diamino acid in the cell-wall peptidoglycan. The G+C content for strain 0166_1T is 72.8 mol%. 16S rRNA gene sequence analysis indicated that this bacterium was related to Conexibacter arvalis KV-962T and Conexibacter stalactiti YC2-25T with 95.5 and 95.2 % sequence similarity, respectively. Based on the phenotypic, genomic and phylogenetic data, we propose the novel species Capillimicrobium parvum sp. nov. (type strain 0166_1T=DSM 104329T=LMG 29999T=CECT 9240T) of the novel genus Capillimicrobium gen. nov. within the novel family Capillimicrobiaceae fam. nov.

Pseudaquidulcibacter saccharophilus gen. nov., sp. nov., a novel member of family Caulobacteraceae, isolated from a water purification facility with supplement of starch as a carbon source

During a survey of microbial communities in the influent (ambient water) and effluent of a water purification facility with aeration and supplement of starch as carbon source, a novel bacterial strain, designated SZ9T, was isolated from the effluent sample. Colonies of strain SZ9T were small (approximately 0.5–1.0 mm in diameter), creamy-white, circular, smooth, translucent and convex. Cells were facultative anaerobic, motile by means of a single polar flagellum, rod-shaped, multiplied by binary fission, Gram-stain-negative, oxidase-positive and catalase-negative. Growth occurred at 10–40 °C (optimum, 28 °C) and pH 5.5–8.0 (optimum, pH 7.5). The range of NaCl concentration for growth was 0–1.0 % (w/v), with an optimum of 0–0.5 % (w/v). Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain SZ9T formed a lineage within the family Caulobacteraceae of the class Alphaproteobacteria and showed the highest 16S rRNA gene sequence similarities to Aquidulcibacter paucihalophilus TH1-2T (92.44%), followed by Vitreimonas flagellata SYSU XM001T (89.61 %), Asprobacter aquaticus DRW22-8T (89.49 %) and Hyphobacterium vulgare WM6T (89.49%). The predominant fatty acids (>10 % of the total fatty acids) of strain SZ9T was summed feature 3 (comprising C16 : 1  ω6c and/or C16 : 1  ω7c), summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c) and C16 : 0. The sole respiratory quinone was ubiquinone-10, and the major polar lipids were phosphatidylcholine and two unidentified glycolipids. The whole genome of strain SZ9T was 2 842 140 bp in size, including 2769 protein-coding genes, 37 tRNA genes and two rRNA genes, and the genomic G+C content was 41.4 mol%. The orthologous average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values between strain SZ9T and other genera within the family Caulobacteraceae were 64.50–66.62 %, 46.96–54.17 % and 27.70–31.70 %, respectively. Therefore, based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, the isolated strain SZ9T could be distinguished from other genera, suggesting that it represents a novel species of a novel genus in the family Caulobacteraceae , for which the name Pseudaquidulcibacter saccharophilus gen. nov., sp. nov is proposed. The type strain is SZ9T (=CCTCC AB2021029T=KCTC 82788T).

Usitatibacter rugosus gen. nov., sp. nov. and Usitatibacter palustris sp. nov., novel members of Usitatibacteraceae fam. nov. within the order Nitrosomonadales isolated from soil

Members of the metabolically diverse order Nitrosomonadales inhabit a wide range of environments. Two strains affiliated with this order were isolated from soils in Germany and characterized by a polyphasic approach. Cells of strains 0125_3^T and Swamp67^T are Gram-negative rods, non-motile, non-spore-forming, non-capsulated and divide by binary fission. They tested catalase-negative, but positive for cytochrome c-oxidase. Both strains form small white colonies on agar plates and grow aerobically and chemoorganotrophically on SSE/HD 1 : 10 medium, preferably utilizing organic acids and proteinaceous substrates. Strains 0125_3^T and Swamp67^T are mesophilic and grow optimally without NaCl addition at slightly alkaline conditions. Major fatty acids are C_16 : 1  ω7c, C_16 : 0 and C_14 : 0. The major polar lipids are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidyglycerol. The predominant respiratory quinone is Q-8. The G+C content for 0125_3^T and Swamp67^T was 67 and 66.1 %, respectively. The 16S rRNA gene analysis indicated that the closest relatives (<91 % sequence similarity) of strain 0125_3^T were Nitrosospira multiformis ATCC 25196^T, Methyloversatilis universalis FAM5^T and Denitratisoma oestradiolicum AcBE2-1^T, while Nitrosospira multiformis ATCC 25196^T, Nitrosospira tenuis Nv1^T and Nitrosospira lacus APG3^T were closest to strain Swamp67^T. The two novel strains shared 97.4 % 16S rRNA gene sequence similarity with one another and show low average nucleotide identity of their genomes (83.8 %). Based on the phenotypic, chemotaxonomic, genomic and phylogenetic analysis, we propose the two novel species Usitatibacter rugosus sp. nov (type strain 0125_3^T=DSM 104443^T=LMG 29998^T=CECT 9241^T) and Usitatibacter palustris sp. nov. (type strain Swamp67^T=DSM 104440^T=LMG 29997^T=CECT 9242^T) of the novel genus Usitatibacter gen. nov., within the novel family Usitatibacteraceae fam. nov.