- Volume 75, Issue 1, 2025

Both the genera Suonthocola and Diplocloster are members of the family Lachnospiraceae. Their type species, both Suonthocola fibrivorans Sanger_33T and Diplocloster agilis ASD5720T, were isolated from human faeces. A comparison of their 16S rRNA gene sequences revealed 100% similarity, suggesting their close relatedness and the possibility of belonging to the same species. To clarify their taxonomic relationship, genome-based analyses were carried out. Overall genomic relatedness indices analyses indicated that S. fibrivorans Sanger_33T shared average amino acid identity and percentage of conserved proteins prediction values higher than the Lachnospiraceae-specific genus-level thresholds with D. agilis ASD5720T, as well as the other two existing species of the genus Diplocloster. Additionally, S. fibrivorans Sanger_33T formed a distinct branch with D. agilis ASD5720T, clustering with the other two species of the genus Diplocloster into the same clade in both the 16S rRNA gene phylogenetic tree and the core-genome phylogenomic tree. Essentially, both the average nucleotide identity and digital DNA–DNA hybridization prediction values between S. fibrivorans Sanger_33T and D. agilis ASD5720T were above the recommended species boundaries. It is thus clear that S. fibrivorans Sanger_33T and D. agilis ASD5720T constitute the same species. On the basis of the earliest valid publication, priority is given to D. agilis Chaplin et al. 2022. Based on this, the orphan species S. fibrivorans Hitch et al. 2022 is reclassified as a later heterotypic synonym of D. agilis Chaplin et al. 2022, along with the reclassification of the genus Suonthocola Hitch et al. 2022 as a later synonym of Diplocloster Chaplin et al. 2022.

A novel Pseudonocardia strain DW16-2T, isolated from duckweed (Spirodela polyrhiza), was taxonomically studied in detail. The analysis based on its 16S rRNA gene sequence revealed that the strain was most closely related to Pseudonocardia carboxydivorans Y8T (98.8%), followed by Pseudonocardia tropica YIM 61452T (98.7%), Pseudonocardia antarctica DVS 5a1T (98.7%) and Pseudonocardia alni DSM 44104T (98.7%). The average nucleotide identity (ANI) based on blast and digital DNA–DNA hybridization (dDDH) relatedness values between strain DW16-2T and their closest type strains were below the threshold values for identifying a novel species. Morphological, physiological and chemotaxonomic features of strain DW16-2T were typical for the genus Pseudonocardia by forming extensively branched substrate mycelium and aerial mycelium that fragmented into rod-shaped spore, with a smooth surface. The whole-cell hydrolysates of strain DW16-2T contained meso-diaminopimelic acid as the diagnostic diamino acid, and the whole-cell sugars were arabinose, galactose, glucose and a trace amount of ribose. The polar lipids contained phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol and unidentified phospholipids. The menaquinone (MK) was MK-8(H4). The cellular fatty acids (>5 %) were iso-C16 : 0, iso-C16 : 1 H, summed feature 3: C16 : 1 ω7c/C16 : 1 ω6c; C16 : 1 ω6c/C16 : 1 ω7c, C17 : 1 ω8c and anteiso-C17 : 0. Characterization based on chemotaxonomic, phenotypic, genotypic and phylogenetic evidence demonstrated that strain DW16-2T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia spirodelae sp. nov. (type strain DW16-2T = TBRC 16418T = NBRC 115857T) is proprosed. In addition, the comparison of the whole genome sequences suggested that P. alni and P. antarctica belong to the same species and P. carboxydivorans is a subspecies of P. alni. Therefore, it is proposed that P. antarctica Prabahar et al. 2004 is reclassified as a later heterotypic synonym of P. alni (Evtushenko et al. 1989) Warwick et al. 1994, and P. carboxydivorans Park et al. 2008 is proposed as a subspecies of P. alni (Evtushenko et al. 1989) Warwick et al. 1994.

Four novel nontuberculous mycobacteria were discovered from a historical strain collection at the International Reference Laboratory of Mycobacteriology at Statens Serum Institut in Copenhagen, Denmark. Phylogenetic analysis combining the 16S rrs, internal transcribed spacer and 23S rrl elements, as well as a single-copy core-gene (hsp65, rpoB+C, secA and tuf) analysis of these freeze-dried mycobacteria, clinically isolated from gastric lavage samples between 1948 and 1955, showed to be associated with type strains grouping within the Terra and Fortuitum-Vaccae clade. Phenotypic characteristics, biochemical properties and fatty acid and mycolic acid profiles supported the classification as novel strains. A genomic comparison to the closest related type strain was done by calculating average nucleotide identity and in silico DNA:DNA hybridization values, which showed 87.9% and 33.0% for Mu0050, 85.2% and 27.4% for Mu0053, 85.3% and 27.6% for Mu0083 and 93.3% and 50.1% for Mu0102, respectively. The names proposed for the new species are Mycobacterium wendilense sp. nov. (Mu0050T=ITM 501390T=CCUG 77525T), Mycobacterium burgundiense sp. nov. (Mu0053T=ITM 501391T=CCUG 77526T), Mycobacterium kokjensenii sp. nov. (Mu0083T=ITM 501392T=CCUG 77527T) and Mycobacterium holstebronense sp. nov. (Mu0102T=ITM 501393T=CCUG 77528T).

A novel Corynebacterium species, strain BD556T, isolated from blood, was identified at Mayo Clinic, Rochester, MN, USA. After failing definitive identification using MALDI-ToF MS and partial 16S rRNA gene sequencing, BD556T was characterized using a polyphasic approach, including phenotypic, biochemical and whole-genome sequencing methods. BD556T was a Gram-positive rod with clubbed ends, facultatively anaerobic, catalase-positive, oxidase-negative and non-motile. Colonies were white, opaque and non-haemolytic with halo-like edges. BD556T grew at 35 °C in room air, with CO2 and under anaerobic conditions. BD556T grew well in 0 and 6% NaCl and weakly in 10% NaCl. The genome size was 2 349 779 bp with a G+C content of 60.39%. Phylogenetic analysis using 16S rRNA gene sequence analysis, average nucleotide identity and digital DNA–DNA hybridization between the genome of BD556T and the closest type strains from the Type Strain Genome Server database yielded separation values well beyond those required for species delineation. Chemotaxonomic analyses of BD556T revealed ribose, arabinose and galactose as whole-cell sugars and an A1γ meso-diaminopimelic acid-direct peptidoglycan type. The major cellular fatty acids were C15 : 0 (21.0%), C16 : 0 (14.8%), C17 : 1 ω9c (26.2%), C17 : 0 (13.3%) and C18 : 1 ω9c (18.3%). Polar lipids included diphosphatidylglycerol, phosphatidylglycerol and unidentified glycolipids and phospholipids. BD556T also contained mycolic acids (32–36 carbons) typical of corynebacteria. The respiratory quinones were dominated by MK-8(H2) (71.2%) and MK-9(H2) (25.9%), with smaller amounts of MK-7(H2) and MK-10(H2). The results presented support the tenet that BD556T (=TSD 427T=NCTC 15078T) is a novel species for which the name Corynebacterium mayonis sp. nov. is proposed.

A clinical isolate, R131, was isolated from the peritoneal swab of a patient who suffered from ruptured appendicitis with abscess and gangrene in Hong Kong in 2018. Cells are facultatively anaerobic, non-motile, Gram-positive coccobacilli. Colonies were small, grey, semi-translucent, low convex and alpha-haemolytic. The bacterium grew on blood agar but not on Brain Heart Infusion (BHI) and Mueller–Hinton agars. It was negative for catalase, oxidase, indole and aesculin hydrolysis. The initial identification attempts via matrix-assisted laser desorption ionization–time of flight mass spectrometry and 16S rRNA gene sequencing yielded inconclusive results. The 16S rRNA gene analysis showed that R131 shared >99% nucleotide identity with certain uncultured Actinomycetales bacteria. In this retrospective investigation, a complete genome of R131 was constructed, disclosing a DNA G+C content of 64%. Phylogenetic analysis showed that the bacterium was mostly related to Scrofimicrobium canadense WB03_NA08, which was first described in 2020. However, its 16S rRNA gene shared only 94.15% nucleotide identity with that of S. canadense WB03_NA08. Notably, the orthoANI between R131 and S. canadense WB03_NA08 was 67.81%. A pan-genome analysis encompassing R131 and 4 Scrofimicrobium genomes showed 986 core gene clusters shared with the Scrofimicrobium species, along with 601 cloud genes. The average nucleotide identity comparisons within the pan-genome analysis ranged from 59.78 to 62.51% between R131 and the other Scrofimicrobium species. Correspondingly, the dDDH values ranged from 19.20 to 22.30%, while the POCP values spanned from 57.48 to 60.94%. Therefore, a novel species, Scrofimicrobium appendicitidis sp. nov., is proposed. The type strain is R131T (=JCM 36615T=LMG 33627T).

Six Gram-reaction-positive, strictly aerobic, mycelium-forming actinobacteria were isolated from soils collected from a natural cave in Jeju, Republic of Korea. The isolates produced well-developed, branched, substrate mycelia and white aerial mycelia that differentiated into straight or flexuous chains of smooth-surfaced spores. Cells showed growth at 15–30 °C, pH 3.5–8.0 and 0–1% (w/v) NaCl. Most of the isolates also grew at pH 10.0. The cell-wall peptidoglycan in common contained ll-diaminopimelic acid, galactose, glucose, mannose and rhamnose. The major menaquinone was MK-9(H6) and MK-9(H8). The polar lipids in common contained phosphatidylglycerol, phosphatidylinositol and an unidentified phospholipid, with the presence of diphosphatidylglycerol and phosphatidylethanolamine in some strains. The predominant fatty acids in common were anteiso-C15 : 0, iso-C16 : 0 and C16 : 0. Strains N1-1T, N1-3 and N1-12 contained genomes of 8.44–8.77 Mbp, and strains N1-5 and N1-10T consisted of genomes of 9.00–9.17 Mbp, while strain N8-3T contained the smallest genome (7.33 Mbp) among the isolates. The genomic DNA G+C contents of the isolates were 71.5–72.2%. Three representatives of the isolates encompassed 16–29 biosynthetic gene clusters predicted to encode for secondary metabolites. The core genome-based phylogenomic tree showed that they formed three distinct clusters within the genus Streptacidiphilus, with the closest relative, the type strain of Streptacidiphilus carbonis, which was also supported by 16S rRNA gene phylogeny. The orthologous average nucleotide identity (≤88.2%) and digital DNA–DNA hybridization (≤30.3%) between three representatives of the isolates and members of the genus Streptacidiphilus and among them supported that the isolates represent three new species of the genus Streptacidiphilus, for which the names Streptacidiphilus alkalitolerans [type strain, N1-1T (=KCTC 19224T=DSM 45080T)], Streptacidiphilus cavernicola [type strain, N8-3T (=KCTC 29470T=DSM 117389T)] and Streptacidiphilus jeojiensis sp. nov. [type strain, N1-10T (=KCTC 19257T=DSM 117391T=NRRL B-24556T)] are proposed.

Ten novel Gram-negative, aerobic, non-sporulating, yellow-pigmented rod-shaped bacterial strains motile by gliding were isolated from marine organisms/environments in French Polynesia. Three of them designated as 190524A05cT, 190524A02bT and 190130A14aT were retrieved from orbicular batfish (Platax orbicularis) mucus. Online database comparisons using 16S rRNA amplicons resulted in over 95% similarity to the genus Tenacibaculum. Phylogenetic analyses based on 679 concatenated core protein sequences revealed that strains 190524A05cT, 190524A02bT and 190130A14aT showed the highest similarity to Tenacibaculum skagerrakense DSM 14836T, Tenacibaculum xiamenense LMG 27422T and Tenacibaculum holothuriorum S2-2T, respectively. Digital DNA–DNA hybridization and average nt identity values between strains 190524A05cT, 190524A02bT and 190130A14aT and other type strains were less than 76.25 and 24.1%, respectively. The DNA G+C content was 31.48, 30.66 and 31.98 mol% for strains 190524A05cT, 190524A02bT and 190130A14aT, respectively. Menaquinone-6 was detected as the major isoprenoid quinone in these three strains. The major polar lipids (phosphatidylethanolamine and aminophospholipid) were similar to the chemotaxonomic profile of other species of the genus Tenacibaculum. Strain 190524A05cT contained summed feature 3 (comprising C16:1 ω7c and/or iso-C15:0 2-OH), iso-C15:1 G, iso-C15:0 and iso-C17:0 3-OH as the major cellular fatty acids. Strain 190524A02bT contained summed feature 3 (comprising C16:1 ω7c and/or iso-C15:0 2-OH), iso-C15:0, iso-C15:1 G and iso-C17:0 3-OH as the major cellular fatty acids. Strain 190130A14aT contained iso-C15:1 G, summed feature 3 (comprising C16:1 ω7c and/or iso-C15:0 2-OH), iso-C15:0 and iso-C17:0 3-OH as the major cellular fatty acids. Based on the phenotypic and molecular features, these three strains represent novel species of the genus Tenacibaculum for which the names Tenacibaculum platacis sp. nov., with 190524A05cT (= CIP 112470T = DSM 118113T) as the type strain; Tenacibaculum vairaonense sp. nov., with 190524A02bT (= CIP 112469T = DSM 118112T) as the type strain; and Tenacibaculum polynesiense sp. nov., with 190130A14aT (= CIP 112468T = DSM 118111T) as the type strain, are proposed.

A polyphasic taxonomic study was carried out on strain T9W2-OT, isolated from the roots of the aquatic plant Salvinia minima. This isolate is rod-shaped, forms yellow/orange pigmented colonies and produces the pigment flexirubin. Nearly complete 16S rRNA gene sequence homology related the strain to Chryseobacterium, with 98.8 and 98.5% similarity to Chryseobacterium profundimaris and Chryseobacterium takakiae, respectively. Average nucleotide identity and digital DNA–DNA hybridization with the closest phylogenetic neighbour of T9W2-OT showed differences at the species level, further confirmed by differences in several physiological characteristics. The main fatty acids are iso C15 : 0, iso C17:1 ω9c, iso C17 : 0 3-OH and summed feature 4 (iso-C15 : 0 2-OH and/or C16:1 ω7c). DNA G+C content is 37.2 mol%. MK-6 is the only menaquinone found, and phosphatidylethanolamine is the dominant polar lipid. Based on the results obtained, this bacterium is assigned to the genus Chryseobacterium as a new species with the name Chryseobacterium salviniae sp. nov., type strain T9W2-OT (=NRRL B-65715T =DSM 118061T).

A novel bacterium, designated 19SA41, was isolated from the air of the Icelandic volcanic island Surtsey. Cells of strain 19SA41 are Gram-stain-negative, strictly aerobic, non-motile rods and form pale yellow-pigmented colonies. The strain grows at 4–30 °C (optimum, 22 °C), at pH 6–10 (optimum, pH 7.5) and with 0–4% NaCl (optimum, 0.5%). Phylogenetic analyses based on 16S rRNA gene sequences showed that 19SA41 belonged to the genus Flavobacterium and is most similar to Flavobacterium xinjiangense DSM 19743T, with a sequence similarity of 96.52%. The new strain contained iso-C15 : 0 (22%) and summed feature 3 (C16∶1ω6c/C16∶1ω7c) (20%) as the predominant fatty acids. The major respiratory quinone was menaquinone-6 (100%). The polar lipid profile consisted of phosphatidylethanolamine and several uncharacterized amino lipids, glycolipids and lipids. The genome of the new strain was 4.01 Mbp, and its G+C content was 33.2 mol%. Based on characterization and comparative results, using a polyphasic taxonomic approach, we propose that the new isolate represents a novel species of the genus Flavobacterium with the name Flavobacterium aerium sp. nov. The type strain is ISCaR-07695T (=DSM 116640T =UBOOC-M-3567T).

Two Gram-stain-negative, curved-rod-shaped, non-motile and aerobic bacteria W6T and I13T were isolated from marine sediment samples collected from Meishan Island located in the East China Sea. Catalase and oxidase activities and hydrolysis of Tween 40, 60 and 80 were positive for both strains, while nitrate reduction, indole production, methyl red reaction and H2S production were negative. Phylogenetic analyses based on 16S rRNA and genome sequences revealed that strains W6T and I13T formed distinct phylogenetic lineages within the genera Ascidiimonas and Leptobacterium, respectively. Strain W6T showed the closest relatedness to Ascidiimonas aurantiaca N5DA8-2CT with 93.9% 16S rRNA gene sequence similarity, 70.7% average nucleotide identity (ANI), 71.0% average amino acid identity (AAI) and 16.4% digital DNA–DNA hybridization (dDDH) values, while strain I13T was most closely related to Leptobacterium flavescens YM3-301T with 92.1% 16S rRNA gene sequence similarity, 70.5% ANI, 72.1% AAI and 17.2% dDDH values. The two novel strains shared 92.0% 16S rRNA gene sequence similarity to each other and were identified as two distinct species based on 70.7% ANI, 70.4% AAI and 17.1% dDDH values calculated using whole-genome sequences. The genomes of strains W6T and I13T were 4.59 Mbp with a G+C content of 34.5 mol% and 2.38 Mbp with a G+C content of 36.2 mol%, respectively. The only respiratory quinone was menaquinone-6, the major polar lipid was phosphatidylethanolamine and the major cellular fatty acids were iso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH. Based on phenotypic, chemotaxonomic and genotypic data, strains W6T and I13T are considered to represent two novel species in the genera Ascidiimonas and Leptobacterium, respectively, in the family Flavobacteriaceae, for which the names Ascidiimonas meishanensis sp. nov. and Leptobacterium meishanense sp. nov. are proposed. The type strains are W6T (=KCTC 102201T=MCCC 1K08928T) and I13T (=KCTC 102202T=MCCC 1K08929T), respectively.

Three bacterial strains, designated FZUC8N2.13T, FBOR7N2.3T and FZUR7N2.5, were isolated from distinct magnesite residues in Spain. Phylogenetic and phylogenomic analysis places them within the genus Flavobacterium. Strains FBOR7N2.3T and FZUR7N2.5 share 100% of similarity in the 16S rRNA gene sequence, and both are most closely related to Flavobacterium cellulosilyticum AR-3-4T with which they share 97.5% of 16S rRNA gene similarity. Strain FZUC8N2.13T forms a distinct lineage most closely related to Flavobacterium lacustre IMCC36792T with 97.7% 16S rRNA gene similarity. The closest phylogenomic neighbours of these three strains are Flavobacterium flevense DSM 1076T, ‘Flavobacterium undicola’ BBQ-18T and Flavobacterium commune PK15T. The average nucleotide identity and digital DNA–DNA hybridization values between the three strains and closest members of the genus Flavobacterium are below the threshold values of 95% and 70%, respectively. Strains FZUC8N2.13T, FBOR7N2.3T and FZUR7N2.5 stain Gram-negative, are rod-shaped and form yellow colonies. Optimum growth occurs at 25 °C and pH 7. The genomic G+C contents are 33.4 mol% for strain FZUC8N2.13T and 33.2 mol% for strains FBOR7N2.3T and FZUR7N2.5. The major isoprenoid quinone is menaquinone 6. The major fatty acids are summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) (22.6–31.1%), iso-C15 : 0 (13.6–16.2 %) and anteiso-C15 : 0 (8.7–10.5%). The polar lipids consist of two aminolipids, two aminophospholipids and one glycolipid. The phylogenetic, phylogenomic, phenotypic and chemotaxonomic data indicate that FZUC8N2.13T, FBOR7N2.3T and FZUR7N2.5 are distinct from the described species of Flavobacterium and should be classified as novel species, for which we propose the names Flavobacterium zubiriense for strain FZUC8N2.13T (=UCCCB 179T=CECT 30977T) and Flavobacterium magnesitis for strains FBOR7N2.3T (=UCCCB 178T=CECT 30976T) and FZUR7N2.5 (=UCCCB 216=CECT 31036).

Four novel bacterial strains were isolated from stagnant water in a clump of Phragmites japonica Steud. The four Gram-negative, facultatively anaerobic, rod-shaped, non-motile and yellow-coloured strains were designated as DGU11T, DGU38T, DGU41T and DGU99T. The four novel strains exhibited 16S rRNA gene similarities with their closest type strains, ranging from 95.7 to 98.7%, average nucleotide identity values from 75.3 to 95.6% and digital DNA–DNA hybridization values between 17.9 and 59.6%. The cells of strain DGU11T were non-motile and grew at 10−30°C (optimum 25 °C), a pH range of 4.0–12.0 (optimum 9.0) and in the presence of 0–1.0% sodium chloride (NaCl) (optimum 0%). The cells of strain DGU38T were non-motile and grew at 10−35°C (optimum 30 °C), a pH range of 4.0–8.0 (optimum 7.0) and at 0 –2.0% NaCl (optimum 0%). The cells of strain DGU41T were non-motile and grew at 15−50°C (optimum 30 °C), a pH range of 6.0–9.0 (optimum 7.0) and in the presence of 0% NaCl (optimum 0%). The cells of strain DGU99T were non-motile and grew at 15−35°C (optimum 25 °C), a pH range of 6.0–12.0 (optimum 9.0) and in the presence of 0 –2.0% NaCl (optimum 0%). The major fatty acid composition of the four novel strains was iso-C15:0 and C16:1  ω7c/C16:1  ω6c, which is similar to other Flavobacterium species. The proposed names of the novel strains are Flavobacterium arundinis sp. nov. (type strain DGU11T=KACC 23722T=TBRC 19004T), Flavobacterium calami sp. nov. (type strain DGU38T=KACC 23723T=TBRC 19005T), Flavobacterium helocola sp. nov. (type strain DGU41T=KACC 23724T=TBRC 19006T) and Flavobacterium flavipallidum sp. nov. (type strain DGU99T=KACC 23725T=TBRC 19007T).

A novel Gram-stain-positive, rod-shaped, endospore-forming bacterium with peritrichous flagella, designated as P96T was isolated from the surface of maize roots. Strain P96T grew optimally at 28 °C, pH 7.0. The strain contained A1γ meso-Dpm-direct in the cell-wall peptidoglycan. The dominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The genome size of strain P96T was 4.8 Mb, and the G+C content was 50.01%. Phylogenomic analyses based on the whole-genome sequences classified the strain into the genus Paenibacillus. The digital DNA–DNA hybridization and average nucleotide identity relatedness analysis resulted in values below the threshold for prokaryotic species delineation, with the highest values observed for Paenibacillus enshidis KCTC 33519T (29.4 and 85.2%, respectively). Genotypic data together with phenotypic properties supported the classification of strain P96T as representative of a novel species of the genus Paenibacillus, for which the name Paenibacillus zeirhizosphaerae sp. nov. is proposed. The type strain is P96T (=LMG 32802T = NCAIM B 02678T).

Three novel strains within the genus Streptococcus (29887T, 29892T and 29896T) were isolated from healthy pigs during routine veterinary physical exams. All three strains were non-motile and non-spore-forming Gram-positive cocci. The complete genome of each strain was attained, and phylogenetic analyses were performed. Comparison of the genomes of 29887T, 29892T and 29896T to the genomes of other Streptococcus strains revealed digital DNA–DNA hybridization (dDDH) values between 21.2% and 53.9% and average nucleotide identity (ANI) values between 70.00% and 94.44%. Phylogenetic analyses suggested that each strain, 29896T (S. suivaginalis sp. nov.), 29887T (S. iners sp. nov.) and 29892T (S. iners subsp. hyiners subsp. nov.), may represent a novel species within the genus Streptococcus, while ANI analysis indicated that strains 29896T (S. suivaginalis sp. nov.) and 29887T (S. iners sp. nov.) represent novel species within the genus Streptococcus, and 29892T (S. iners subsp. hyiners subsp. nov.) represents a novel subspecies of 29887T (S. iners sp. nov.). Based upon the combined data presented in this study, two novel species, Streptococcus suivaginalis sp. nov. (type strain, 29896T=NRRL B-65677T=NCTC 14941T) and Streptococcus iners sp. nov. (type strain, 29887T=NRRL B-65675T=NCTC 14939T) are proposed, and one novel subspecies, Streptococcus iners subsp. hyiners subsp. nov. (type strain, 29892T=NRRL B-65676T=NCTC 14940T) is proposed.

An erratum of this article has been published full details can be found at https://doi.org/10.1099/ijsem.0.006671

A crude oil aggregation-forming, strictly anaerobic, Gram-stain-positive, spore-forming, rod-shaped, motile and mesophilic bacterium, named strain SH18-2T, was isolated from marine sediment near Sado Island in the Sea of Japan. The temperature, salinity and pH ranges of this strain for the growth were 15–40 °C (optimum 35 °C), 0.5–6.0% NaCl (w/v; optimum 2.0%) and pH 6.0–8.0 (optimum 7.5), respectively. A phylogenetic analysis of the 16S rRNA gene sequence showed that this strain belongs to the genus Clostridium. It was most closely related to Clostridium grantii A-1T (97.02% homology). The draft genome size was 5616089 bp, with a G+C content of 29.7 mol%. The digital DNA–DNA hybridization values determined using the Genome-to-Genome Distance Calculator and the average nucleotide identity between this strain and C. grantii A-1T were 20.30 and 78.24%, respectively. Whole-organism hydrolysates of strain SH18-2T contained meso-diaminopimelic acid; the major fatty acid was C16:0, and the polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, glycolipid and three unidentified polar lipids. From the results of genotypic, phenotypic and chemotaxonomic analyses, SH18-2T (=NBRC 116030T=DSM 115762T) is the type strain and represents a novel species of the genus Clostridium, and the name Clostridium sediminicola sp. nov. is proposed.