Cryo-EM structure of an active bacterial TIR-STING filament complex.

Stimulator of interferon genes (STING) is an antiviral signalling protein that is broadly conserved in both innate immunity in animals and phage defence in prokaryotes1-4. Activation of STING requires its assembly into an oligomeric filament structure through binding of a cyclic dinucleotide4-13, 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 mammals5. 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.

Racemization of the substrate and product by serine palmitoyltransferase from Sphingobacterium multivorum yields two enantiomers of the product from d-serine.

Serine palmitoyltransferase (SPT) catalyzes the pyridoxal-5'-phosphate (PLP)-dependent decarboxylative condensation of l-serine and palmitoyl-CoA to form 3-ketodihydrosphingosine (KDS). Although SPT was shown to synthesize corresponding products from amino acids other than l-serine, it is still arguable whether SPT catalyzes the reaction with d-serine, which is a question of biological importance. Using high substrate and enzyme concentrations, KDS was detected after the incubation of SPT from Sphingobacterium multivorum with d-serine and palmitoyl-CoA. Furthermore, the KDS comprised equal amounts of 2S and 2R isomers. 1H-NMR study showed a slow hydrogen-deuterium exchange at Cα of serine mediated by SPT. We further confirmed that SPT catalyzed the racemization of serine. The rate of the KDS formation from d-serine was comparable to those for the α-hydrogen exchange and the racemization reaction. The structure of the d-serine-soaked crystal (1.65 Å resolution) showed a distinct electron density of the PLP-l-serine aldimine, interpreted as the racemized product trapped in the active site. The structure of the α-methyl-d-serine-soaked crystal (1.70 Å resolution) showed the PLP-α-methyl-d-serine aldimine, mimicking the d-serine-SPT complex prior to racemization. Based on these enzymological and structural analyses, the synthesis of KDS from d-serine was explained as the result of the slow racemization to l-serine, followed by the reaction with palmitoyl-CoA, and SPT would not catalyze the direct condensation between d-serine and palmitoyl-CoA. It was also shown that the S. multivorum SPT catalyzed the racemization of the product KDS, which would explain the presence of (2R)-KDS in the reaction products.

Structural insights into the substrate recognition of serine palmitoyltransferase from Sphingobacterium multivorum.

Serine palmitoyltransferase (SPT) is a key enzyme of sphingolipid biosynthesis, which catalyzes the pyridoxal-5'-phosphate-dependent decarboxylative condensation reaction of l-serine (l-Ser) and palmitoyl-CoA (PalCoA) to form 3-ketodihydrosphingosine called long chain base (LCB). SPT is also able to metabolize l-alanine (l-Ala) and glycine (Gly), albeit with much lower efficiency. Human SPT is a membrane-bound large protein complex containing SPTLC1/SPTLC2 heterodimer as the core subunits, and it is known that mutations of the SPTLC1/SPTLC2 genes increase the formation of deoxy-type of LCBs derived from l-Ala and Gly to cause some neurodegenerative diseases. In order to study the substrate recognition of SPT, we examined the reactivity of Sphingobacterium multivorum SPT on various amino acids in the presence of PalCoA. The S. multivorum SPT could convert not only l-Ala and Gly but also l-homoserine, in addition to l-Ser, into the corresponding LCBs. Furthermore, we obtained high-quality crystals of the ligand-free form and the binary complexes with a series of amino acids, including a nonproductive amino acid, l-threonine, and determined the structures at 1.40 to 1.55 Å resolutions. The S. multivorum SPT accommodated various amino acid substrates through subtle rearrangements of the active-site amino acid residues and water molecules. It was also suggested that non-active-site residues mutated in the human SPT genes might indirectly influence the substrate specificity by affecting the hydrogen-bonding networks involving the bound substrate, water molecules, and amino acid residues in the active site of this enzyme. Collectively, our results highlight SPT structural features affecting substrate specificity for this stage of sphingolipid biosynthesis.

Sphingobacterium tenebrionis sp. nov., isolated from intestine of mealworm.

A bacterial strain designated PU5-4T was isolated from the mealworm (the larvae of Tenebrio molitor) intestines. It was identified to be Gram-stain-negative, strictly aerobic, rod-shaped, non-motile, and non-spore-forming. Strain PU5-4T was observed to grow at 10-40 °C, at pH 7.0-10.0, and in the presence of 0-3.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain PU5-4T should be assigned to the genus Sphingobacterium. The 16S rRNA gene sequence similarity analysis showed that strain PU5-4T was closely related to the type strains of Sphingobacterium lactis DSM 22361T (98.49 %), Sphingobacterium endophyticum NYYP31T (98.11 %), Sphingobacterium soli NCCP 698T (97.69 %) and Sphingobacterium olei HAL-9T (95.73 %). The predominant isoprenoid quinone is MK-7. The major fatty acids were identified as iso-C15 : 0, iso-C17 : 03-OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and summed feature 9 (iso-C17 : 0 ω9c). The polar lipids are phosphatidylethanolamine, one unidentified phospholipid, and six unidentified lipids. The genomic DNA G+C content of strain PU5-4T is 40.24 mol%. The average nucleotide identity of strain PU5-4T exhibited respective values of 73.88, 73.37, 73.36 and 70.84 % comparing to the type strains of S. lactis DSM 22361T, S. soli NCCP 698T, S. endophyticum NYYP31T and S. olei HAL-9T, which are below the cut-off level (95-96 %) for species delineation. Based on the above results, strain PU5-4T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium temoinsis sp. nov. is proposed. The type strain is PU5-4T (=CGMCC 1.61908T=JCM 36663T).

Sphingobacterium oryzagri sp. nov., isolated from rice paddy soil.

An aerobic, Gram-stain-negative and short rod-shaped bacterial strain, designated M6-31T, was isolated from rice paddy soil sampled in Miryang, Republic of Korea. Growth was observed at 4-35 °C (optimum, 28 °C), pH 6.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 0-4 % (w/v) NaCl (optimum, 0 % w/v). Phylogenetic analysis based on 16S rRNA gene sequences grouped strain M6-31T with Sphingobacterium bambusae IBFC2009T, Sphingobacterium griseoflavum SCU-B140T and Sphingobacterium solani MLS-26-JM13-11T in the same clade, with the 16S rRNA gene sequence similarities ranging from 95.8 to 96.6 %. A genome-based phylogenetic tree reconstructed by using all publicly available Sphingobacterium genomes placed strain M6-31T with S. bambusae KACC 22910T, 'Sphingobacterium deserti' ACCC 05744T, S. griseoflavum CGMCC 1.12966T and Sphingobacterium paludis CGMCC 1.12801T. Orthologous average nucleotide identity and digital DNA-DNA hybridization values between strain M6-31T and its closely related strains were lower than 74.6 and 22.0 %, respectively. The respiratory quinone was menaquinone-7, and the major polar lipid was phosphatidylethanolamine. The major fatty acids (>10 %) were C15 : 0 iso, C17 : 0 iso 3OH and summed feature 3. The phenotypic, chemotaxonomic and genotypic data obtained in this study showed that strain M6-31T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium oryzagri sp. nov. (type strain M6-31T=KACC 22765T=JCM 35893T) is proposed.

Proposal of Sphingobacterium allocomposti nom. nov., Mycobacterium chelonae subsp. bovistauri nom. nov. and Lactobacillus delbrueckii subsp. allosunkii nom. nov. as new names with replacement specific or subspecific epithets, respectively, for three illegitimate prokaryotic names Sphingobacterium composti Yoo et al. 2007, Mycobacterium chelonae subsp. bovis Kim et al. 2017 and Lactobacillus delbrueckii subsp. sunkii Kudo et al. 2012; proposal of Christiangramia oceanisediminis comb. nov. and Christiangramia crocea comb. nov. as replacement names respectively for two illegitimate prokaryotic names Gramella oceanisediminis Yang et al. 2023 and Gramella crocea Zhang et al. 2023.

As required by Rule 54 of the International Code of Nomenclature of Prokaryotes, the authors propose the replacement specific epithet 'allocomposti' for the illegitimate prokaryotic name Sphingobacterium composti Yoo et al. 2007, the replacement subspecific epithet 'bovistauri' for Mycobacterium chelonae subsp. bovis Kim et al. 2017 and the replacement subspecific epithet 'allosunkii' for Lactobacillus delbrueckii subsp. sunkii Kudo et al. 2012. Meanwhile, new combinations Christiangramia oceanisediminis and Christiangramia crocea are also proposed as replacements for the illegitimate prokaryotic names Gramella oceanisediminis Yang et al. 2023 and Gramella crocea Zhang et al. 2023, respectively.

Identification and characterization of a deaminoneuraminic acid (Kdn)-specific aldolase from Sphingobacterium species.

Sialic acid (Sia) is a group of acidic sugars with a 9-carbon backbone, and classified into 3 species based on the substituent group at C5 position: N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc), and deaminoneuraminic acid (Kdn). In Escherichia coli, the sialate aldolase or N-acetylneuraminate aldolase (NanA) is known to catabolize these Sia species into pyruvate and the corresponding 6-carbon mannose derivatives. However, in bacteria, very little is known about the catabolism of Kdn, compared with Neu5Ac. In this study, we found a novel Kdn-specific aldolase (Kdn-aldolase), which can exclusively degrade Kdn, but not Neu5Ac or Neu5Gc, from Sphingobacterium sp., which was previously isolated from a Kdn-assimilating bacterium. Kdn-aldolase had the optimal pH and temperature at 7.0-8.0 and 50 °C, respectively. It also had the synthetic activity of Kdn from pyruvate and mannose. Site-specific mutagenesis revealed that N50 residue was important for the Kdn-specific reaction. Existence of the Kdn-aldolase suggests that Kdn-specific metabolism may play a specialized role in some bacteria.

Soluble extracellular polymeric substance (SEPS) of histo-blood group antigen (HBGA) expressing bacterium Sphingobacterium sp. SC015 influences the survival and persistence of norovirus on lettuce.

Foodborne norovirus (NoV) outbreaks linked to leafy greens are common due to a lack of efficient strategies to prevent NoV spread from contaminated surfaces. We previously found that Sphingobacterium sp. SC015 in lettuce phyllosphere expresses histo-blood group antigen (HBGA)-like substances in soluble extracellular polymeric substances (SEPS) that contribute to NoV adherence on lettuce. Here, we extracted SEPS from bacterium SC015 (SEPS-SC015), analyzed their chemical composition, and examined their roles in the survival and protection of NoV and surrogates [murine norovirus (MNV-1) and Tulane virus (TuV)] on lettuce. Presence of SEPS-SC015 significantly increased survival and persistence of human NoV (HuNoV), MNV-1, and TuV at days 7 and 14, compared with virus alone. HuNoV, TuV, and MNV-1 seeded with SEPS-SC015 were more resistant to heat (70 °C, 2 min) than these viruses alone. SEPS-SC015 also increased viral resistance to sodium hypochlorite inactivation by treatment with 30 and 300 ppm bleach at 26 °C for 10 min. However, SEPS-SC015 was not effective at protecting these viruses under UV inactivation. Binding of TuV to SC015 bacteria and SEPS-SC015, visualized using transmission electron microscopy, suggests that protection might be related to direct interaction between SEPS-SC015 and viral particles. This study provides important insights that will help inform strategies to improve food safety.

Organoarsenical tolerance in Sphingobacterium wenxiniae, a bacterium isolated from activated sludge.

Organoarsenicals enter the environment from biogenic and anthropogenic sources. Trivalent inorganic arsenite (As(III)) is microbially methylated to more toxic methylarsenite (MAs(III)) and dimethylarsenite (DMAs(III)) that oxidize in air to MAs(V) and DMAs(V). Sources include the herbicide monosodium methylarsenate (MSMA or MAs(V)), which is microbially reduced to MAs(III), and the aromatic arsenical roxarsone (3-nitro-4-hydroxybenzenearsonic acid or Rox), an antimicrobial growth promoter for poultry and swine. Here we show that Sphingobacterium wenxiniae LQY-18T , isolated from activated sludge, is resistant to trivalent MAs(III) and Rox(III). Sphingobacterium wenxiniae detoxifies MAs(III) and Rox(III) by oxidation to MAs(V) and Rox(V). Sphingobacterium wenxiniae has a novel chromosomal gene, termed arsU1. Expressed in Escherichia coli arsU1 confers resistance to MAs(III) and Rox(III) but not As(III) or pentavalent organoarsenicals. Purified ArsU1 catalyses oxidation of trivalent methylarsenite and roxarsone. ArsU1 has six conserved cysteine residues. The DNA sequence for the three C-terminal cysteines was deleted, and the other three were mutated to serines. Only C45S and C122S lost activity, suggesting that Cys45 and Cys122 play a role in ArsU1 function. ArsU1 requires neither FMN nor FAD for activity. These results demonstrate that ArsU1 is a novel MAs(III) oxidase that contributes to S. wenxiniae tolerance to organoarsenicals.

Sphingobacterium faecale sp. nov., a 1-aminocyclopropane-1-carboxylate deaminase producing bacterium isolated from camel faeces.

An investigation of the diversity of 1-aminocyclopropane-1-carboxylate deaminase producing bacteria associated with camel faeces revealed the presence of a novel bacterial strain designated C459-1T. It was Gram-stain-negative, short-rod-shaped and non-motile. Strain C459-1T was observed to grow optimally at 35 °C, at pH 7.0 and in the presence of 0 % NaCl on Luria-Bertani agar medium. The cells were found to be positive for catalase and oxidase activities. The major fatty acids (>10 %) were identified as iso-C15 : 0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and iso-C17 : 0 3-OH. The predominant menaquinone was MK-7. The major polar lipids consisted of phosphatidylethanolamine, one sphingophospholipid, two unknown aminophospholipids, three unknown glycolipids and five unknown lipids. The genomic DNA G+C content was 40.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain C459-1T was affiliated with the genus Sphingobacterium and had the highest sequence similarity to Sphingobacterium tabacisoli h337T (97.0 %) and Sphingobacterium paucimobilis HER1398T (95.6 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain C459-1T and S. tabacisoli h337T were 83.8 and 33.8 %, respectively. Phenotypic characteristics including enzyme activities and carbon source utilization differentiated strain C459-1T from other Sphingobacterium species. Based on its phenotypic, chemotaxonomic and phylogenetic properties, strain C459-1T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium faecale sp. nov. is proposed, with strain is C459-1T (CGMCC 1.18716T=KCTC 82381T) as the type strain.

Cholangitis with Sphingobacterium multivorum and Acinetobacter junii bacteremia in a patient with gastric cancer: A case report.

INTRODUCTION: Sphingobacterium is an aerobic, glucose non-fermenting, Gram-negative rod bacterium that has been isolated from soil, plants, food, and water sources, including in hospitals. Reports of systemic infections caused by Sphingobacterium multivorum (S. multivorum) are rare, and their clinical and microbiological characteristics remain unclear. Moreover, conventional microbiological methods have limited ability to identify S. multivorum. We report the first case of obstructive cholangitis with bacteremia caused by S. multivorum in a patient with gastric cancer. CASE REPORT: A 68-year-old woman with advanced gastric cancer, hypertension, and hyperlipidemia was admitted with obstructive jaundice, and subsequently developed obstructive cholangitis during the hospital stay. S. multivorum were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S ribosomal RNA sequencing of the patient's blood samples. Based on the antibiotic susceptibility results of the isolates, cefepime was administered intravenously for 14 days, with good therapeutic outcomes. CONCLUSIONS: S. multivorum infection is rare, and its microbiology and pathogenicity in humans is mostly unknown. Therefore, multiple diagnostic approaches should be used to identify S. multivorum, and antimicrobial therapy should be selected based on the in vitro susceptibility. This report provides clinicians with novel information on the clinical manifestations and diagnostic methods for an accurate diagnosis of S. multivorum.

Sphingobacterium bovistauri sp. nov., Isolated from the Faeces of Bos Taurus.

A novel bacterium designated WQ 366 T was isolated from the faeces of Bos taurus, foraging on the slopes of the Baima Snow Mountain in Yunnan, China. The isolate grew optimally at 30 â„ƒ and pH 7.0-8.0 without NaCl. The cells were Gram-stain-negative, aerobic, rod-shaped, non-gliding, catalase-positive, and produced yellow color colonies on Columbia Agar. A polyphasic study was applied to clarify its taxonomic position through 16S rRNA gene and genome sequence analysis, and other extensive biological typing. Phylogenetic analysis revealed that the isolate was affiliated to the genus Sphingobacterium and its 16S rRNA gene sequence was closely related to Sphingobacterium bovisgrunnientis YK2 T (97.3%), Sphingobacterium composti T5-12 T (96.4%), and Sphingobacterium cavernae 5.0403-2 T (96.4%). The calculated whole genome average nucleotide identity (ANI) and the digital DNA-DNA hybridization values between strain WQ 366 T and the three related strains were 78.3, 78.6, 73.9 and 21.2, 21.2, 21.0%, respectively. The predominant fatty acids (>10%) were iso-C15:0, iso-C17:0 3-OH, Summed Feature 3 (C16:1 ω7c and/or C16:1 ω6c), and Summed feature 9 (iso-C17:1 ω9c and 10-methyl C16:0). The main polar lipids were PE, GPL, GL, and PL. MK-7 was the major menaquinone. The genome size and the G + C content of WQ 366 T was 4.1 Mb and 34.6%, respectively. All these results indicated that strain WQ 366 T represents a novel species of the Sphingobacterium genus. Therefore, the name Sphingobacterium bovistauri sp. nov. is proposed, and the type strain is WQ 366 T (= CCTCC AA 2020029 T = KCTC 82395 T).

Cyanide removal from aqueous environment by resting cells and PTFE immobilized cells of Sphingobacterium spp.

Microbial detoxification of cyanide offered an inexpensive, safe, and viable alternative to physiochemical processes for the treatment of cyanide in industrial effluents or contaminated sites. This study involved isolation of novel strain with high resistance against cyanide toxicity and able to degrade the cyanide radical. The strain was isolated from rocky area and identified as Sphingobacterium multivorium using 16S ribosomal RNA. Resting pregrown cells were used in simple reaction mixture to avoid the complication associated with the media. One-gram fresh weight of this bacteria was able to remove 98.5% from 1.5 g/L cyanide which is a unique result. Factor affecting the biochemical process such as pH, temperature, agitation, glucose concentration was examined. The optimum conditions were, pH 6-7, 30-40°C, and 100-150 rpm shaking speed and 0.25% glucose. Furthermore, the cells were used after immobilization in polytetrafluoroethylene (PTFE) polymer. The PTFE is very safe carrier and the cells withstand the entrapment process and were able to remove 92% (1 g/L cyanide). The immobilized cells were used for six successive cycles with about 50% removal efficiency. The storage life extended to 14 days. No previous work studied the cyanide removal by Sphingobacterium spp. The strain showed good applicable characters.

Metagenomics study to compare the taxonomic composition and metabolism of a lignocellulolytic microbial consortium cultured in different carbon conditions.

A lignocellulolytic microbial consortium holds promise for the in situ biodegradation of crop straw and the comprehensive and effective utilization of agricultural waste. In this study, we applied metagenomics technology to comprehensively explore the metabolic functional potential and taxonomic diversity of the microbial consortia CS (cultured on corn stover) and FP (cultured on filter paper). Analyses of the data on metagenomics taxonomic affiliations revealed considerable differences in the taxonomic composition and carbohydrate-active enzymes profile of the microbial consortia CS and FP. Pseudomonas, Dysgonomonas and Sphingobacterium in CS and Cellvibrio and Pseudomonas in FP had a much wider distribution of lignocellulose degradative ability. The genes for more lignocellulose degradative enzymes were detected when the relatively simple substrate filter paper was used as the carbon source. Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analyses revealed considerable levels of similarity, and carbohydrate metabolic and amino acid metabolic pathways were the most enriched in CS and FP, respectively. The mechanism used by the two microbial consortia to degrade lignocellulose was similar, but the annotation of quantity of genes indicated that they are diverse and vary greatly. These data underlie the interactions between microorganisms and the synergism of enzymes during the degradative process of lignocellulose under different substrates and suggest the development of potential microbial resources.

Sphingobacterium rhinopitheci sp. Nov., isolated from the faeces of Rhinopithecus bieti in China.

A novel bacterium, WQ 047T, was isolated from the faeces of Rhinopithecus bieti, a highly endangered primate endemic to China. The cells were aerobic, oval/rod-shaped, Gram-stain-negative, non-motile, catalase positive, and produced yellow pigmented colonies on Columbia Agar. The taxonomic position of WQ 047T was clarified by applying a polyphasic study based on 16S rRNA gene sequence phylogenetic analysis, extensive biological typing, and whole genome sequencing. Phylogenetic analysis indicated that stain WQ 047T belonged to the genus Sphingobacterium and its 16S rRNA gene sequence exhibited 96.47% pairwise similarity with that of the closest relatives Sphingobacterium nematocida M-SX103T. The calculated whole genome average nucleotide identity (ANI) value between strain WQ 047T and strain M-SX103 was 72.3%. The digital DNA-DNA hybridization value of strain WQ 047T and M-SX103T was 15.73%, which was obtained by calculating the genome-to-genome distance. The major fatty acids were C15:0 iso, C17:0 iso 3-OH, Summed Feature 3 (C16:1 ω7c/C16:1 ω6c) and Summed feature 9 (iso-C17:1ω9c and/or 10-methyl C16:0). The predominant polar lipids were PE, PL and APL. MK-7 was the predominant menaquinone. The G + C content of WQ 047T was 34.89 mol% according to genome analysis. All these characteristics were consistent with those of the genus of Sphingobacterium. Therefore, based on these results, we propose a novel species for which the name Sphingobacterium rhinopitheci sp. Nov. is proposed, with the type strain WQ 047T (= CCTCC AA 2020026T = KCTC82393T).

Sphingobacterium phlebotomi sp. nov., a new member of family Sphingobacteriaceae isolated from sand fly rearing substrate.

A Gram-stain-negative, rod-shaped, non-motile, non-spore-forming, aerobic bacterium, designated type strain SSI9T, was isolated from sand fly (Phlebotomus papatasi Scopoli; Diptera: Psychodidae) rearing substrate and subjected to polyphasic taxonomic analysis. Strain SSI9T contained phosphatidylethanolamine as a major polar lipid, MK-7 as the predominant quinone, and C16 : 1ω6c/C16 : 1ω7c, iso-C15 : 0, iso-C17 : 0 3-OH and C16 : 0 as the major cellular fatty acids. Phylogenetic analysis based on 16S rRNA gene sequences revealed that SSI9T represents a member of the genus Sphingobacterium, of the family Sphingobacteriaceae sharing 96.5-88.0 % sequence similarity with other species of the genus Sphingobacterium. The results of multilocus sequence analysis using the concatenated sequences of the housekeeping genes recA, rplC and groL indicated that SSI9T formed a separate branch in the genus Sphingobacterium. The genome of SSI9T is 5 197 142 bp with a DNA G+C content of 41.8 mol% and encodes 4395 predicted coding sequences, 49 tRNAs, and three complete rRNAs and two partial rRNAs. SSI9T could be distinguished from other species of the genus Sphingobacterium with validly published names by several phenotypic, chemotaxonomic and genomic characteristics. On the basis of the results of this polyphasic taxonomic analysis, the bacterial isolate represents a novel species within the genus Sphingobacterium, for which the name Sphingobacterium phlebotomi sp. nov. is proposed. The type strain is SSI9T (=ATCC TSD-210T=LMG 31664T=NRRL B-65603T).

Sphingobacterium micropteri sp. nov. and Sphingobacterium litopenaei sp. nov., isolated from aquaculture water.

Two novel bacterial strains, designated as DN00404T and DN04309T, were isolated from aquaculture water and characterized by using a polyphasic taxonomic approach. Cells of strains DN00404T and DN04309T were Gram-stain-negative, aerobic, non-motile, oxidase-positive and catalase-positive. Cells of DN00404T were short rod-shaped and those of DN04309T were long rod-shaped. Strain DN00404T was found to grow at 15-37 °C (optimum, 25-30 °C), at pH 6.0-11.0 (optimum, pH 7.5) and in 0-2.0 % (w/v) NaCl (optimum, 1.0 %). Strain DN04309T was found to grow at 15-45 °C (optimum, 20-37 °C), at pH 5.5-11.0 (optimum, 7.5) and in 0-4.0 % (w/v) NaCl (optimum, 0.5 %). Phylogenetic analyses based on 16S rRNA gene and genome sequences revealed that the two strains belonged to the genus Sphingobacterium and were distinct from all known species of this genus. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains and between each of the two strains and related type strains of this genus were well below the recognized thresholds of 95.0-96.0 % ANI and 70.0 % dDDH for species delineation. The genomic DNA G+C contents of strains DN00404T and DN04309T were 41.6 and 36.0 mol%, respectively. The respiratory quinone in both strains was identified as MK-7, and their major fatty acids were iso-C15 : 0 and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c), which were similar to those of other species of this genus. The two major fatty acids C16 : 0 and iso-C17 : 0 3-OH were also found in strain DN00404T. Based on genotypic and phenotypic characteristics, two novel species of the genus Sphingobacterium are proposed: Sphingobacterium micropteri sp. nov. with DN00404T (=GDMCC 1.1865T=KACC 21924T) as the type strain and Sphingobacterium litopenaei sp. nov. with DN04309T (=GDMCC 1.1984T=KCTC 82348T) as the type strain.

Sphingobacterium hungaricum sp. nov. a novel species on the borderline of the genus Sphingobacterium.

A Gram-reaction-negative bacterial strain, designated Kb22T, was isolated from agricultural soil and characterized using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, the strain shows highest similarity (94.39 %) to Sphingobacterium nematocida M-SX103T. The highest average nucleotide identity value (71.83 %) was found with Sphingobacterium composti T5-12T, and the highest amino acid identity value (66.65 %) was found with Sphingobacterium olei HAL-9T. Cells are aerobic, non-motile rods. The isolate was found to be positive for catalase and oxidase tests. The assembled genome of strain Kb22T has a total length of 4,06 Mb, the DNA G+C content is 38.1 mol%. The only isoprenoid quinone is menaquinone 7 (MK-7). The major fatty acids are iso-C15:0 (28.4%), summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH) (25.7 %) and iso-C17:0 3-OH (19.7 %). Based on phenotypic characteristics and phylogenetic results, it is concluded that strain Kb22T is a member of the genus Sphingobacterium and represents a novel species for which the name Sphingobacterium hungaricum sp. nov. is proposed. The type strain of the species is strain Kb22T (=LMG 31574T=NCAIM B.02638T).

Sphingobacterium prati sp. nov., isolated from agricultural soil and involved in lignocellulose deconstruction.

A bacterial strain, arapr2T, was isolated from agricultural soil sampled in Reims, France. Based on its 16S rRNA gene sequence, the strain was affiliated to the family Sphingobacteriaceae and more specifically to the genus Sphingobacterium. The strain had 98.31 % 16S rRNA gene sequence similarity to its closest relative Sphingobacterium canadense CR11T and 98.25 % to Sphingobacterium pakistanensis NCCP-246T. Genome relatedness indexes revealed that the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between arapr2T and its closest relative (S. canadense CR11T) were 92.97 % and 52.00 %, respectively; for S. pakistanensis NCCP-246T, the ANI and dDDH values were 82.46 and 27.6%, respectively. The genomic DNA of strain arapr2T was 6.02 Mbp long, had a DNA G+C content of 40.4 mol% and had 5504 protein-coding genes. The results obtained in this study suggests that strain arapr2T (CIP 111872T=LMG 31848T) represents a new species for which the name Sphingobacterium prati sp. nov. is proposed. Due to the fact that this strain has been isolated using wheat straw as carbon source, this novel bacterial strain represents a promising biotechnological tool for the fractionation of lignocellulosic biomass in the context of biorefinery development.

Sphingobacterium lumbrici sp. nov., a novel bacterium isolated from wormcast of Eisenia foetida.

A novel Gram-stain-negative, rod-shaped, non-motile, yellowish bacterium, designated strain 1.3611T, was isolated from the wormcast of Eisenia foetida. The strain grew optimally at 30-37 ℃, at pH 7.0 and with 0-1.0 % (w/v) NaCl. Based on the results of 16S rRNA gene sequence and phylogenetic analyses, strain 1.3611T showed the highest degree of 16S rRNA gene sequence similarity to Sphingobacterium olei HAL-9T (97.0 %), followed by Sphingobacterium alkalisoli Y3L14T (95.8 %). The respiratory quinone of strain 1.3611T was menaquinone-7 (MK-7) and its major cellular fatty acids were iso-C15 : 0 (41.3 %), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c, 22.1 %) and iso-C17 : 0 3-OH (16.2 %). The major polar lipids were sphingophospholipid, phosphatidylethanolamine, four unidentified glycolipids, two unidentified phospholipids and five unidentified polar lipids. The genomic DNA G+C content was 39.0 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between the genomes of strain 1.3611T and S. olei HAL-9T were 37.9 and 88.9 %, respectively. According to the phenotypic and chemotaxonomic phylogenetic results, strain 1.3611T should represent a novel species of the genus Sphingobacterium, for which the name Sphingobacterium lumbrici sp. nov. is proposed, with strain 1.3611T (=KCTC 62980T=CCTCC AB 2018349T) as the type strain.