- Volume 75, Issue 4, 2025

In this paper, the comparative genome analysis was used to re-evaluate the taxonomic relationship between Paraglaciecola chathamensis and Paraglaciecola agarilytica. The 16S rRNA gene sequence analysis indicated that P. chathamensis S18K6T shared the highest sequence identity with P. agarilytica NO2T (99.9%), Paraglaciecola mesophila KMM 241T (99.2%) and Paraglaciecola polaris LMG 21857T (98.5%). Phylogenetic analysis based on 16S rRNA gene sequences and whole-genome sequences showed that P. chathamensis S18K6T was most closely related to P. agarilytica NO2T. However, the average nucleotide identity and digital DNA–DNA hybridization values among them were greater than the threshold of 95–96% and 70 % for the delineation of prokaryotic genomic species, confirming that they represented the same species. Besides, phenotypic characteristics and chemotaxonomic properties between P. agarilytica KCTC 12755T and P. chathamensis JCM 13645T were almost identical, further verifying this result. Consequently, we propose that P. agarilytica (Yong et al. 2007) Shivaji and Reddy 2014 is a later heterotypic synonym of P. chathamensis (Matsuyama et al. 2006) Shivaji and Reddy 2014.

A culture-dependent bioprospecting strategy, based on the use of several selective isolation media, revealed the presence of relatively high numbers of streptomycete-like colonies from machair grassland soil, in which carbonate minerals dominate. Representatives were shown to be bioactive in primary and secondary antimicrobial screens conducted through standard plug assays. The comparison of the whole-genome sequences showed that four of the isolates were novel species in the genus Streptomyces, for which the names Streptomyces caledonius sp. nov. (=DSM 118365; =NCIMB 15554), Streptomyces machairae sp. nov. (=DSM 118363; =NCIMB 15553), Streptomyces pratisoli sp. nov. (=DSM 118364; =NCIMB 15555) and Streptomyces achmelvichensis sp. nov. (=NCIMB 15556; =DSM 118366) are proposed. Genomes of the novel strains were found to be rich in biosynthetic gene clusters predicted to encode for diverse, specialized metabolites, notably antibiotics. They also contained stress-related genes that provided an insight into how streptomycetes cope with the prevailing conditions in machair grassland soils. It can be concluded that selective isolation and dereplication of streptomycetes from the unique machair habitat provides a practical way of isolating novel Streptomyces strains for ecological and biotechnological studies.

A strain with aerial hyphae presented, designated KC 131T, was isolated from lead–zinc mine tailings, Lanping, Yunnan province, Southwest China. The strain was Gram-stain-positive, acid-alcohol-fast, aerobic and non-motile. Based on 16S rRNA gene sequence and phylogeny analysis, strains Nocardia ninae NBRC 108245T (98.4%), Nocardia alba YIM 30243T (98.4%) and Nocardia colli CICC 11023T (98.2%) were the most closely related species of strain KC 131T, and the four strains were in one cluster. The meso-diaminopimelic acid, arabinose and galactose were detected in the whole-cell hydrolysates. The mycolic acids were presented, and the major fatty acids (>5%) were C16:0 (30.0%), C18:1 ω9c (12.5%), C18:0 (7.5%), 10-methyl C18:0 (27.3%) and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c; 12.4%). The menaquinone was MK-8 (H4, ω-cyclo), and the major polar lipids were diphosphatidylglycerol and phosphatidylethanolamine. All these features were consistent with the genus Nocardia. Digital DNA–DNA hybridization values between strain KC 131T and N. ninae NBRC 108245T, N. alba DSM 44684T and N. colli CICC 11023T were 23.8%, 20.9% and 23.5%, respectively. The average nucleotide identity values between strain KC 131T and the three strains were 80.0%, 76.5% and 80.0%, respectively. In addition, some physiological and biochemical characteristics were also different. Thus, strain KC 131T represents a novel species of the genus Nocardia, for which the name Nocardia arseniciresistens sp. nov. is proposed. The type strain is KC 131T (=CGMCC 1.19493T=JCM 35916T).

A novel bacterial strain, designated DS6T, was isolated from the commercial soil for biofertilization and characterized as a novel species within the Actinomycetota phylum. The morphological and biochemical analysis revealed that strain DS6T is a Gram-positive, rod-shaped bacterium with pili, forming ivory colonies on R2A agar after 3 days of incubation at 25 °C. The strain shows a broad growth pH range of 4–9, with an optimum pH of 8, and can tolerate temperatures between 20 and 45 °C, optimally growing at 37 °C. Salinity tolerance ranges from 0% to 5%, with optimal growth occurring at 0–1%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain DS6T is closely related to Nocardioides marinus KCCM 4231T (96.4%), Nocardioides panaciterrulae KCTC 19471T (96.3%), Nocardioides gansuensis KCTC 49117T (96.3%) and Nocardioides ginkgobilobae KCTC 39594T (96.2%). Biochemical tests showed that the strain is oxidase negative and catalase positive. The major fatty acids were C16 : 0 iso (26.85%) and C18 : 0 10-methyl (15.9%). The major respiratory quinone was MK-8 (H4) and the strain contained ll-2,6-diaminopimelic acid as the cell-wall diamino acid. The major polar lipids consist of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phospholipids, phosphatidylinositolmannosides and unknown lipids. The DNA G+C mol% of genomic DNA is 71.3. Based on its distinct phylogenetic, phenotypic and biochemical characteristics, strain DS6T is proposed to represent a novel species of the genus Nocardioides, for which the name Nocardioides eburneus sp. nov. is proposed. The type strain is DS6T (KEMB 22008T=KCTC 59264T=JCM 37205T).

An actinomycete, designated strain Q6T, was isolated from tea plant rhizosphere soil sample in Hefei, China. Strain Q6T produced straight chains of smooth-surfaced spores and grew well on International Streptomyces Project 1–7 media. Phenotypic and genotypic analyses indicated that strain Q6T represented a member of the genus Streptomyces. The 16S rRNA gene sequence data of strain Q6T indicated that strain Q6T had the highest sequence similarity to Streptomyces xanthii CRXT-Y-14T (98.9%), Streptomyces davaonensis JCM 4913T (98.9%) and Streptomyces atriruber NRRL B-24165T (98.9%), followed by Streptomyces adustus WH-9T (98.8%), Streptomyces avermitilis MA-4680T (98.6%) and Streptomyces kunmingensis NBRC 14463T (98.6%). The phylogenomic tree, using the genome blast distance phylogeny method, showed that strain Q6T represents a new branch among the Streptomyces and has the closest genetic relationship with S. kunmingensis 80–3024T. The diagnostic diamino acid was ll-diaminopimelic acid. The major menaquinones were MK-9 (H6), MK-9 (H8) and MK-8 (H6). The dominant fatty acids were C16 : 0 (18.6%), iso-C16 : 0 (18.3%), anteiso-C15 : 0 (15.4%) and summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c; 13.8%). The main polar lipids were diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine (PE) and phosphatidylinositol mannoside. The DNA G+C content of strain Q6T was 71.3 mol%. Average nucleotide identity and digital DNA–DNA hybridization values between the genome sequence of strain Q6T and its closely related type strains were 77.0–87.5% and 22.4–29.7%, respectively. On the basis of these data, strain Q6T represents a novel species within the genus Streptomyces, for which the name Streptomyces citrinus sp. nov. is proposed. The type strain is strain Q6T (=CGMCC 4.7886T=NBRC 116061T).

A novel actinobacterial strain, designated as SMS 1(5)aT, was isolated from the rhizosphere soil of Podocarpus rumphii in Laiwangi Wanggameti National Park, Indonesia. A comprehensive polyphasic approach was used to determine its taxonomic position. Strain SMS 1(5)aT exhibited the highest 16S rRNA gene sequence similarity to Peterkaempfera griseoplana NRRL B-3064T (98.89%), followed by Peterkaempfera bronchialis DSM 106435T (98.68%). Phylogenetic and phylogenomic analyses confirmed its affiliation with the genus Peterkaempfera. The genome size of strain SMS 1(5)aT was 8.8 Mb, with a DNA G+C content of 72 mol%. Digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain SMS 1(5)aT and P. griseoplana NRRL B-3064T were 41.9 and 90.47%, respectively, which were below the established thresholds for species delineation. Strain SMS 1(5)aT grew between 15 and 40 °C, within a pH range of 5–8, and showed tolerance to 0–2% (w/v) NaCl. The morphological and chemotaxonomic properties of strain SMS 1(5)aT were consistent with those of Peterkaempfera. The strain formed long, flexuous-to-spiral spore chains with a warty surface. The whole-cell hydrolysates of strain SMS 1(5)aT contained  ll -diaminopimelic acid ( ll -DAP) as the diagnostic diamino acid as well as whole-cell sugars, including glucose, mannose and ribose. The predominant menaquinone was MK-9(H8), and its polar lipid profile included phosphatidylethanolamine (PE), phosphatidylinositol (PI) and diphosphatidylglycerol (DPG). Additionally, the major fatty acid in strain SMS 1(5)aᵀ was iso-C15:0, differentiating it from the other two type strains. Characterization based on genotypic, genomic, phenotypic and chemotaxonomic studies suggests strain SMS 1(5)aT as a novel species of the genus Peterkaempfera, for which the name Peterkaempfera podocarpi sp. nov. (type strain SMS 1(5)aT = InaCC A1244T = NBRC 116964T) is proposed.

A Gram-positive, aerobic, non-motile coccoid bacterium, designated strain ZF39T, was isolated from a farm in Quandian Village, Zhengzhou City, Henan Province, China, and subjected to taxonomic characterization. Optimal growth occurred at 32 ℃, pH 7.0 and 0–1% NaCl (w/v). Mannose and glucose were identified as the sugar components in the whole-cell hydrolysates. The strain’s peptidoglycan type was classified as A3γ (ll-Dpm-Gly), and MK-9(H4) was identified as the predominant respiratory quinone. Aminoglycolipid, aminophospholipid, glycolipids, phosphatidylglycerol and phospholipid were detected as the major polar lipids. The predominant cellular fatty acids were anteiso-C15 : 0 (48.7%) and iso-C15 : 0 (20.2%). Phylogenetic analysis based on 16S rRNA gene sequences placed strain ZF39T within the family Propionibacteriaceae. The strain formed a distinct genetic lineage adjacent to the genus Desertihabitans, with 16S rRNA gene sequence similarities of 94.70% to Desertihabitans aurantiacus CPCC 204711T and 94.56% to Desertihabitans brevis KCTC 49116T. The genomic G+C content was 67.7 mol%. Genome comparisons revealed that the average nucleotide identity values between strain ZF39T and D. aurantiacus CPCC 204711T, D. brevis KCTC 49116T, Granulicoccus phenolivorans DSM 17626T were 72.50%, 71.98% and 72.36%, respectively. Moreover, phylogenetic analysis and phenotypic characterization supported the classification of strain ZF39T as a novel species of a new genus within the family Propionibacteriaceae. The name Ammonicoccus fulvus gen. nov., sp. nov. is proposed, with ZF39T (=CGMCC 1.60047T=KCTC 59250T=MCCC 1K08851T) as the type strain.

A novel strain, KQZ13P-5T, was isolated from the bark of Sonneratia apetala collected from Maowei Sea Mangrove Nature Reserve of Guangxi Zhuang Autonomous Region, China. Cells of strain KQZ13P-5T were Gram-stain-positive, aerobic and non-spore producing. A polyphasic taxonomic approach was investigated to resolve its taxonomic position. The conditions for the growth of strain KQZ13P-5T were at 20–37 °C (optimum 30–37 °C), pH 5.0–8.5 (optimum pH 6.5–7.5) and with 0–4% (w/v) NaCl (optimum 0%). Phylogenetic analysis based on 16S rRNA gene sequence and genome sequence showed that strain KQZ13P-5T formed a stable and coherent branch with Micropruina glycogenica Lg2T and shared the highest 16S rRNA gene sequence similarity of 98.2% with M. glycogenica Lg2T. The average nucleotide identity and estimated digital DNA–DNA hybridization values between strain KQZ13P-5T and M. glycogenica Lg2T were 80.2% and 24.0%, respectively, far below the interspecies threshold. The G+C content of DNA of strain KQZ13P-5T was 70.5%. The polar lipids included diphosphatidylglycerol, phosphatidylglycerol, two unidentified lipids and one unidentified glycolipid. It contained anteiso-C15 : 0, iso-C16 : 0 and C16 : 0 as the major fatty acids and MK-9(H4) as the predominant menaquinone. The cell wall diagnostic diamino acid was meso-diaminopimelic acid (DAP). Based on phylogenetic, genomic, phenotypic and chemotaxonomic data, strain KQZ13P-5T represents a novel species of genus Micropruina for which the name Micropruina sonneratiae sp. nov. is proposed. The type strain is KQZ13P-5T (=JCM 34552T= CGMCC 1.18968T). The description of the genus Micropruina has also been emended.

Two mesophilic, hydrogenotrophic methanogens, WWM1085 and M. smithii GRAZ-2, were isolated from human faecal samples. WWM1085 was isolated from an individual in the United States and represents a novel species within the genus Methanobrevibacter. M. smithii GRAZ-2 (=DSM 116045) was retrieved from a faecal sample of a European, healthy woman and represents a novel strain within this species. Both Methanobrevibacter representatives form non-flagellated, short rods with variable morphologies and the capacity to form filaments. Both isolates showed the typical fluorescence of F420 and methane production. Compared to M. smithii GRAZ-2, WWM1085 did not accumulate formate when grown with H2 and CO2. The optimal growth conditions were at 35–39 °C and pH 6.5–7.5. Full genome sequencing revealed a genomic difference of WWM1085 to the type strain of M. smithii DSM 861 (=PST), with 93.55% average nucleotide identity (ANI) and major differences in the sequence of its mcrA gene (3.3% difference in nucleotide sequence). Differences in the 16S rRNA gene sequence were very minor, and thus distinction based on this gene marker might not be possible. M. smithii GRAZ-2 was identified as a novel strain within the species Methanobrevibacter smithii (ANI 99.04% to M. smithii DSM 861 [=PST]). Due to the major differences between WWM1085 and M. smithii type strain M. smithii DSM 861 (=PST) in phenotypic, genomic and metabolic features, we propose Methanobrevibacter intestini sp. nov. as a novel species with WWM1085 as the type strain (DSM 116060T = CECT 30992T).

Two novel, non-motile, Gram-stain-negative, rod-shaped bacterial strains, designated AS60T and WG47T, were isolated from freshwater in South Korea. To clarify their taxonomic positions, both strains were characterized based on genomic information, including 16S rRNA gene and draft genome sequences. Phylogenetic analyses revealed that both isolates belong to the genus Flavobacterium. Based on 16S rRNA gene sequencing, AS60T clustered with Flavobacterium silvisoli KACC 21178T (96.09%), Flavobacterium cheonhonense KACC 14967T (96.07%) and Flavobacterium sangjuense KACC 17473T (95.96%). Strain WG47T showed the highest similarity to Flavobacterium dankookense KACC 23179T (97.14%), F. cheonhonense KACC 14967T (97.07%) and Flavobacterium chungnamense KACC 14971T (96.71%). The draft genomes of AS60T and WG47T were 3.07 and 3.30 Mb, with G+C contents of 35.6 and 38.9 mol%, respectively. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values were calculated. For AS60T, ANI values compared to F. silvisoli KACC 21178T, F. cheonhonense KACC 14967T and WG47T were 76.67, 79.38 and 76.01%, respectively, with dDDH values of 20, 19.6 and 22.1%. For WG47T, ANI values compared to F. dankookense KACC 23179T and F. cheonhonense KACC 14967T were 75.12 and 74.75%, with dDDH values of 19.9 and 19.2%. Both strains exhibited MK-6 as the predominant respiratory quinone, and their fatty acid profiles included iso-C15:1, iso-C15:0 3OH, iso-C15:1 G, iso-C16:0, iso-C16:0 3OH and iso-C17:0 3OH. Phosphatidylethanolamine was the major polar lipid. Strain WG47T was found to produce flexirubin-type pigments, while AS60T did not. These results, combined with phenotypic and biochemical data, suggest that strains AS60T and WG47T represent two novel species of Flavobacterium, for which the names Flavobacterium anseongense sp. nov. (AS60T=KACC 22413T=LMG 32491T) and Flavobacterium wongokense sp. nov. (WG47T=KACC 22407T=LMG 32500T) are proposed.

An aerobic, Gram-stain-positive, rod-shaped and non-motile bacterium, designated strain P10A9, was isolated from the rhizosphere soil of Pu-erh tea plants (Camellia sinensis var. assamica) in an organic tea garden in the Jingmai Pu-erh Tea District, Pu'er City, Yunnan Province, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain P10A9 belongs to the genus Sinomonas, with its closest relative being Sinomonas atrocyanea KCTC 3377T (98.4% similarity). The major fatty acids (>10.0% of the total) were anteiso-C15 : 0 and anteiso-C17:0. The predominant respiratory quinone was MK-9(H2), with MK-8(H2) as a minor component. The major polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and glycolipids. The peptidoglycan contained glutamic acid (Glu), lysine (Lys), aspartic acid (Asp), serine (Ser), alanine (Ala) and glycine (Gly). The genome of strain P10A9 is 4.3 Mbp in size, with a G+C content of 69.2 mol%. Digital DNA–DNA hybridization values between strain P10A9 and other Sinomonas species ranged from 20.8 to 25.1%, and the average nucleotide identity values were significantly below the species delineation threshold (95–96%). Based on these results, strain P10A9 represents a novel species of the genus Sinomonas, for which the name Sinomonas puerhi sp. nov. is proposed. The type strain is P10A9T (=CCTCC AB 2024154T=KCTC 59368T).

A rod-shaped, white-pigmented, non-motile, Gram-stain-negative bacterium, designated RHL897T, was isolated from sediments collected at the Mariana Trench Challenger Deep (10,816 m). Strain RHL897T was strictly aerobic and grew at 4–37 °C, pH 6.0–10.0 and in the presence of 0–11.0 % (w/v) NaCl. Its genomic DNA G+C content was 41.2%. Metabolic analysis revealed mechanisms for salt tolerance, abundant metal ion transport proteins and stronger resistance to heavy metals such as arsenic and mercury compared to the closest reference strains, likely linked to adaptation to the hadal sediment environment. The predominant menaquinone was MK-7, and the major polar lipids were phosphatidylethanolamine, an unidentified aminophospholipid and an unidentified glycolipid. The main fatty acids were iso-C15 : 0, summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c) and iso-C17 : 0 3OH. Strain RHL897T exhibited the highest 16S rRNA gene sequence similarity to the type strain of Pedobacter indicus (97.9%) and Albibacterium bauzanense (96.1%). Phylogenetic trees constructed based on 16S rRNA gene sequences and a 549 core gene set indicated that strain RHL897T was closely related to P. indicus and A. bauzanense, with all three species clustering within a distinct clade. Combined with the analyses of average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization, strain RHL897T represented a novel species of the genus Albibacterium, for which the name Albibacterium profundi sp. nov. is proposed. The type strain is RHL897T (=MCCC 1K09221T=KCTC 102276T). Furthermore, the revised phylogeny with the inclusion of RHL897T suggested that P. indicus should be reclassified under the genus Albibacterium and renamed Albibacterium indicum.

Three novel bacterial strains, 172403-2T, BT310T and BT731T, were isolated from UV-irradiated soil samples collected in South Korea. All strains are Gram-negative, aerobic, non-motile and grow at 20–35 °C, optimally at 30 °C and pH 7.0. The optimal NaCl concentration for strains 172403-2T and BT310T is 1.5%, while strain BT731T grows optimally in the absence of NaCl (0.0%). Phylogenetic analysis based on 16S rRNA gene sequences positioned these strains within the genus Pontibacter, with strain 172403-2T closest to Pontibacter chitinilyticus (95.96%), BT310T to Pontibacter pudoricolor (97.87%) and BT731T to Pontibacter virosus (98.06%). Cellular fatty acid profiles identified C15:0 iso and Summed Feature 4 as predominant fatty acids. All strains contained ubiquinone MK-7 and phosphatidylethanolamine as major respiratory quinone and primary polar lipids, respectively. Genome sizes were 5.08 Mb for 172403-2T, 4.29 Mb for BT310T and 4.66 Mb for BT731T, with average nucleotide identity and digital DNA–DNA hybridization values with other Pontibacter species ranging between 70.41%–88.56% and 11.55%–24.66%, respectively. These biochemical, chemotaxonomic and phylogenetic analyses confirm that strains 172403-2T, BT310T and BT731T represent three novel species of Pontibacter, proposed as Pontibacter rufus sp. nov. (172403–2T = KCTC 62072 T=NBRC 114967T), Pontibacter humidus sp. nov. (BT310T = KCTC 72363T = NBRC 114846T) and Pontibacter coccineus sp. nov. (BT731T = KCTC 92910T = NBRC 116069T).

A Gram-negative bacterial strain, designated ACPtT, was isolated from the top of the covering soil of an active charcoal-burning pile. The cells of ACPtT were strictly anaerobic, rod-shaped and grew optimally at 40 °C and pH 7. The substrates ribose, glucose, sucrose, raffinose, melezitose, pyruvate, vanillate, syringate, methanol and CO were utilized for growth. Phylogenomic analysis of the 4.1 Mb genome showed that strain ACPtT represented a novel species of the genus Sporomusa. The most closely related species to ACPtT was Sporomusa malonica, with an average amino acid identity of 80.1%. The genome of ACPtT encoded cytochromes, ubiquinones, the Wood–Ljungdahl gene cluster and an Rnf complex, which were identified as common features of all Sporomusa type strains. However, strain ACPtT did not ferment H2+CO2 via acetogenesis as other Sporomusa species but employed the metabolism of a carboxydotrophic hydrogenogen, converting CO to H2+CO2. Based on the genomic, morphological and physiological features presented in this study, strain ACPtT is proposed as a novel species in the genus Sporomusa, with the name Sporomusa carbonis sp. nov. (DSM 116159T and CCOS 2105T).

Two obligately anaerobic, Gram-stain-negative, non-spore-forming, rod-shaped, motile and mesophilic bacteria, designated as strains AN17-1T and AN17-2T, were isolated from deep-marine sediments collected from the western Pacific Ocean. The phylogenetic analysis based on the 16S rRNA gene with the most closely related species showed 98.5 and 98.8% similarities of strains AN17-1T and AN17-2T with Vallitalea guaymasensis Ra1766G1T, respectively. The genome sizes and G+C contents of strains AN17-1T and AN17-2T were 6.0 Mb and 30.3 mol% and 5.4 Mb and 30.9 mol%, respectively. The genome-to-genome distance and the average nucleotide identity values between strains AN17-1T and AN17-2T and V. guaymasensis Ra1766G1T were lower than the thresholds for species delimitation. Elemental sulphur, sulphate, thiosulphate, sulphite, fumarate, nitrate and nitrite were not used as terminal electron acceptors by strains AN17-1T and AN17-2T. The most abundant fatty acids of strains AN17-1T and AN17-2T were iso-C15:0 and C16:0, respectively. The commonly detected polar lipids of both strains were diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, glycolipid, two unidentified phospholipids and one unidentified polar lipid. The results suggest that strains AN17-1T and AN17-2T represent novel species of the genus Vallitalea. Therefore, the new names, Vallitalea sediminicola sp. nov. and Vallitalea maricola sp. nov., are proposed for strains AN17-1T (=NBRC 115486T=DSM 116091T) and AN17-2T (=NBRC 115487T=DSM 116092T) as the type strains, respectively.

An obligately anaerobic bacterial strain (TW13T) affiliated with the family Clostridiaceae within the class Clostridia was isolated from an anoxic soil sample subjected to reductive soil disinfestation. Cells of the strain were stained Gram-positive and spore-forming straight rods with a polar flagellum. The strain was saccharolytic and decomposed polysaccharides (glucomannan, pectin, starch and xylan). The strain produced acetate, butyrate and H2 as fermentation products from carbohydrates utilized. The major cellular fatty acids of strain TW13T were C18:1 ω7c dimethylacetal, C16:0 and C17:1 ω8c/C17:2 (as summed feature). The most closely related species of strain TW13T based on the 16S rRNA gene sequences was Inconstantimicrobium porci WCA-383-APC-5BT with a sequence identity of 96.3%. The next closely related species were all in the genus Clostridium with sequence identities of up to 95.9% (for the type species of the genus, Clostridium butyricum DSM 10702T, 93.9%). The genome analysis of strain TW13T indicated that the genome size was 4.64 Mb, and the genomic DNA G+C content was 30.3 mol%. Strain TW13T had genes related to the production of acetate, butyrate and H2, degradation of polysaccharides (mannan, pectin, starch and xylan) and glycogen metabolism. The values of the average amino acid identity and the percentage of conserved proteins between the genomes of strain TW13T and I. porci WCA-383-APC-5BT or C. butyricum DSM 10702T were 67.6 and 50.5% or 62.9 and 43.0%, respectively. Based on the phylogenetic, genomic and phenotypic analyses, Inconstantimicrobium mannanitabidum sp. nov. in the family Clostridiaceae is proposed to accommodate strain TW13T (= NBRC 112100T = DSM 114758T).

An anaerobic, spore-forming, 3-hydroxybutyrate (3-HB)-producing bacterium, strain IPX_CKT, was isolated from sediment of a meromictic lake located in Massif Central (France). Cells were rods, forming filamentous chains which were observed moving under the microscope. Strain IPX_CKT utilized a wide variety of carbohydrates, but not raffinose, rhamnose and starch. Hydrogen (H2), 3-HB, acetate and ethanol were the main fermentative end-products from growth in medium containing glucose. Strain IPX_CKT grew optimally at 37 °C and pH 7. Its closest phylogenetic relative was Kineothrix alysoides (16S rRNA gene sequence identity 98.7%, isDDH 34.6%, ANIb 87.4%). The genomic DNA G+C content was 43.0 mol%. As for K. alysoides, whole-genome sequencing suggested that strain IPX_CKT is capable of fixing nitrogen (N2). However, strain IPX_CKT carried a five-nif-gene-set (nifHDKEB), not present in K. alysoides. Genome sequence also showed a high number of encoded chemotaxis receptors (42 genes, the second highest in the family Lachnospiraceae after K. alysoides). Based on phenotypic, genomic, phylogenetic and chemotaxonomic analyses, it is proposed that a novel species, Kineothrix sedimenti sp. nov., be created, with strain IPX_CKT (DSM 118044T, CIP 112511T) as the type strain.