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Stimulator of interferon genes (STING) is an antiviral signalling protein that is broadly conserved in both innate immunity in animals and phage defence in prokaryotes 1 – 4 . Activation of STING requires its assembly into an oligomeric filament structure through binding of a cyclic dinucleotide 4 – 13 , but the molecular basis of STING filament assembly and extension remains unknown. Here we use cryogenic electron microscopy to determine the structure of the active Toll/interleukin-1 receptor (TIR)–STING filament complex from a Sphingobacterium faecium cyclic-oligonucleotide-based antiphage signalling system (CBASS) defence operon. Bacterial TIR–STING filament formation is driven by STING interfaces that become exposed on high-affinity recognition of the cognate cyclic dinucleotide signal c-di-GMP. Repeating dimeric STING units stack laterally head-to-head through surface interfaces, which are also essential for human STING tetramer formation and downstream immune signalling in mammals 5 . The active bacterial TIR–STING structure reveals further cross-filament contacts that brace the assembly and coordinate packing of the associated TIR NADase effector domains at the base of the filament to drive NAD + hydrolysis. STING interface and cross-filament contacts are essential for cell growth arrest in vivo and reveal a stepwise mechanism of activation whereby STING filament assembly is required for subsequent effector activation. Our results define the structural basis of STING filament formation in prokaryotic antiviral signalling. Through structural analysis of the activation of bacterial STING, the molecular basis of STING filament formation and TIR effector domain activation in antiphage signalling is defined.

A novel Gram-negative bacterium, designated ZWT, was isolated from a soil sample of the Western Desert of China, and its phenotypic properties and phylogenetic position were investigated using a polyphasic approach. Growth occurred on TGY medium at 5-42 degree C with an optimum of 30 degree C, and at pH 7.0-11.0 with an optimum of pH 9.0. The predominant cellular fatty acids were summed feature 3 (C16:1 omega 7c/C16:1 omega 6c or C16:1 omega 6c/C16:1 omega 7c) (39.22%), iso-C15:0 (27.91%), iso-C17:0 3OH (15.21%), C16:0 (4.98%), iso-C15:0 3OH (3.03%), C16:0 3OH (5.39%) and C14:0 (1.74%). The major polar lipid of strain ZWT is phosphatidylethanolamine. The only menaquinone observed was MK-7. The GC content of the DNA of strain ZWT is 44.9 mol%. rDNA phylogeny, genome relatedness and chemotaxonomic characteristics all indicate that strain ZWT represents a novel species of the genus Sphingobacterium. We propose the name S. deserti sp. nov., with ZWT (= KCTC 32092T = ACCC 05744T) as the type strain. Whole genome optical mapping and next-generation sequencing was used to derive a finished genome sequence for strain ZWT, consisting of a circular chromosome of 4,615,818 bp in size. The genome of strain ZWT features 3,391 protein-encoding and 48 tRNA-encoding genes. Comparison of the predicted proteome of ZWT with those of other sphingobacteria identified 925 species-unique proteins that may contribute to the adaptation of ZWT to its native, extremely arid and inhospitable environment. As the first finished genome sequence for any Sphingobacterium, our work will serve as a useful reference for subsequent sequencing and mapping efforts for additional strains and species within this genus.

Sphingobacterium hotanense is a gram-negative bacillus identified in 2013 from soil samples that rarely causes infection in humans. We describe 2 cases of S. hotanense bacteremia secondary to skin and soft tissue infection in immunocompromised patients in Minnesota, USA, highlighting S. hotanense as a potential pathogen in immunocompromised hosts with environmental exposure.

The taxonomic status of a bacterium, strain NCCP-246ᵀ, isolated from rhizosphere of Vigna mungo, was determined using a polyphasic taxonomic approach. The strain NCCP-246ᵀ can grow at 16–37 °C (optimum 32 °C), at pH ranges of 6–8 (optimum growth occurs at pH 7) and in 0–4 % (w/v) NaCl. Phylogenetic analysis based upon on 16S rRNA gene sequence comparison revealed that strain NCCP-246ᵀ belonged to genus Sphingobacterium. Strain NCCP-246ᵀ showed highest similarity to the type strain of Sphingobacterium canadense CR11ᵀ (97.67 %) and less than 97 % with other species of the genus. The DNA–DNA relatedness value of strain NCCP-246ᵀ with S. canadense CR11ᵀ and Sphingobacterium thalpophilum JCM 21153ᵀ was 55 and 44.4 %, respectively. The chemotaxonomic data revealed the major menaquinone as MK-7 and dominant cellular fatty acids were summed feature 3 [C₁₆:₁ ω7c/C₁₆:₁ ω6c] (37.07 %), iso-C₁₅:₀ (28.03 %), C₁₆:₀ (11.85 %), C₁₇:₀ cyclo (8.84 %) and C₁₄:₀ (2.42 %). The G+C content of the strain was 39.2 mol%. On the basis of DNA–DNA hybridization, phylogenetic analyses, physiological and, biochemical data, strain NCCP-246ᵀ can be differentiated from the validly named members of genus Sphingobacterium and thus represents as a new species, for which the name, Sphingobacterium pakistanensis sp. nov. is proposed with the type strain NCCP-246ᵀ (= JCM18974 ᵀ = KCTC 23914ᵀ).

Sulfamethoxazole (SMX) is the most commonly used antibiotic in worldwide for inhibiting aquatic animal diseases. However, the residues of SMX are difficult to eliminate and may enter the food chain, leading to considerable threats on human health. The bacterial strain Sphingobacterium mizutaii LLE5 was isolated from activated sludge. This strain could utilize SMX as its sole carbon source and degrade it efficiently. Under optimal degradation conditions (30.8 °C, pH 7.2, and inoculum amount of 3.5 × 10 7  cfu/mL), S. mizutaii LLE5 could degrade 93.87% of 50 mg/L SMX within 7 days. Four intermediate products from the degradation of SMX were identified and a possible degradation pathway based on these findings was proposed. Furthermore, S. mizutaii LLE5 could also degrade other sulfonamides. This study is the first report on (1) degradation of SMX and other sulfonamides by S. mizutaii , (2) optimization of biodegradation conditions via response surface methodology, and (3) identification of sulfanilamide, 4-aminothiophenol, 5-amino-3-methylisoxazole, and aniline as metabolites in the degradation pathway of SMX in a microorganism. This strain might be useful for the bioremediation of SMX-contaminated environment.

Vast expanses of Earth's surface are covered by ice, with microorganisms in these systems affecting local and global biogeochemical cycles. We examined microbial assemblages from habitats fed by glacial meltwater within the McMurdo Dry Valleys, Antarctica and on the west Greenland Ice Sheet (GrIS), evaluating potential physicochemical factors explaining trends in community structure. Microbial assemblages present in the different Antarctic dry valley habitats were dominated by Sphingobacteria andFlavobacteria, while Gammaproteobacteria and Sphingobacteria prevailed in west GrIS supraglacial environments. Microbial assemblages clustered by location (Canada Glacier, Cotton Glacier and west GrIS) and were separated by habitat type (i.e. ice, cryoconite holes, supraglacial lakes, sediment and stream water). Community dissimilarities were strongly correlated with dissolved organic matter (DOM) quality. Microbial meltwater assemblages were most closely associated with different protein-like components of the DOM pool. Microbes in environments with mineral particles (i.e. stream sediments and cryoconite holes) were linked to DOM containing more humic-like fluorescence. Our results demonstrate the establishment of distinct microbial communities within ephemeral glacial meltwater habitats, with DOM-microbe interactions playing an integral role in shaping communities on local and polar spatial scales.

A strictly aerobic and facultatively psychrophilic bacterium, strain 3-0-1 T , was isolated from Lake Yamdrok on the Tibetan Plateau, China. Cells were Gram-negative and short-rod-shaped. Strain 3-0-1 T formed circular, opaque, yellow colonies, and grew at 0–5 % (w/v) NaCl, pH 5.0–11.0 and 5–35 °C. Phylogenetic analysis based on 16S rRNA gene sequences of various species with validly published names showed that strain 3-0-1 T belongs to the genus Sphingobacterium , family Sphingobacteriaceae , sharing the highest similarity with Sphingobacterim nematocida M-SX103 T (96.62 %) and less than 95 % similarity with all the other species in the genus Sphingobactrium . The predominant isoprenoid quinone of strain 3-0-1 T was identified as menaquinone 7 (MK-7), the major polar lipid was identified as phosphatidylethanolamine and the DNA G+C content was determined to be 42.5 mol%. The predominant cellular fatty acids were identified as summed feature 3 (C 16:1 ω 7 c and/or C 16:1 ω 6 c ) (>30 %), iso-C 15:0 (>20 %) and iso-C 17:0 3-OH (>10 %). Based on the variability of phylogenetic and phenotypic characteristics, strain 3-0-1 T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium yamdrokense sp. nov. is proposed. The type strain is 3-0-1 T (=JCM 19397 T  = CGMCC 1.12560 T ).

Endo-β- N -acetylglucosaminidase (ENGase) catalyzes hydrolysis of N -linked oligosaccharides. Although many ENGases have been characterized from various organisms, so far no fucose-containing oligosaccharides-specific ENGase has been identified in any organism. Here, we screened soil samples, using dansyl chloride (Dns)-labeled sialylglycan (Dns-SG) as a substrate, and discovered a strain that exhibits ENGase activity in the culture supernatant; this strain, named here as strain HMA12, was identified as a Sphingobacterium species by 16S ribosomal RNA gene analysis. By draft genome sequencing, five candidate ENGase encoding genes were identified in the genome of this strain. Among them, a recombinant protein purified from Escherichia coli expressing the candidate gene ORF1188 exhibited fucose-containing oligosaccharides-specific ENGase activity. The ENGase exhibited optimum activities at very acidic pHs (between pH 2.3–2.5). A BLAST search using the sequence of ORF1188 identified two fungal homologs, one in Beauveria bassiana and the other in Cordyceps militaris . Recombinant ORF1188, Beauveria and Cordyceps ENGases released the fucose-containing oligosaccharides residues from rituximab (immunoglobulin G) but not the high-mannose-containing oligosaccharides residues from RNase B, a result that not only confirmed the substrate specificity of these novel ENGases but also suggested that natural glycoproteins could be their substrates.

A Gram-reaction-negative halotolerant bacterial strain, designated Ka21T, was isolated from agricultural soil and characterised using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, highest similarity was found with Sphingobacterium alkalisoli Y3L14T (96.72%). Cells were observed to be aerobic, non-motile rods. The isolate was found to be able to grow between 0 and 10% of NaCl concentration. The assembled genome of strain Ka21T has a total length of 5.2 Mb with a G + C content of 41.0 mol%. According to the genome analysis, Ka21T encodes several glycoside hydrolases that may play a role in the degradation of accumulated plant biomass in the soil. Based on phenotypic characteristics and phylogenetic analysis, it is concluded that strain Ka21T represents a novel species in the Sphingobacterium genus for which the name Sphingobacterium pedocola sp. nov. is proposed. The type strain of the species is strain Ka21T (= LMG 31575T = NCAIM B.02636T).

A phytase with high activity at neutral pH and typical water temperatures (~25°C) could effectively hydrolyze phytate in aquaculture. In this study, a phytase-producing strain, Pedobacter nyackensis MJ11 CGMCC 2503, was isolated from glacier soil, and the relevant gene, PhyP, was cloned using degenerate PCR and thermal asymmetric interlaced PCR. To our knowledge, this is the first report of detection of phytase activity and cloning of phytase gene from Pedobacter. PhyP belongs to beta-propeller phytase family and shares very low identity (~28.5%) with Bacillus subtilis phytase. The purified recombinant enzyme (r-PhyP) from Escherichia coli displayed high specific activity for sodium phytate of 24.4 U mg⁻¹. The optimum pH was 7.0, and the optimum temperature was 45°C. The K m, V max, and k cat values were 1.28 mM, 71.9 μmol min⁻¹ mg⁻¹, and 45.1 s⁻¹, respectively. Compared with Bacillus phytases, r-PhyP had higher relative activity at 25°C (r-PhyP (>50%), B. subtilis phytase (<8%)) and hydrolyzed phytate from soybean with greater efficacy at neutral pH. These characteristics suggest that r-PhyP might be a good candidate for an aquatic feed additive in the aquaculture industry.