- Volume 75, Issue 12, 2025

Four Gram-stain-positive bacterial strains, designated as YY-01T, YY-02T, YY-03T and YY-04, were isolated from pit mud (YY-01T, YY-02T and YY-04) and daqu (YY-03T) samples collected at a winery in Shandong Province, China. Phylogenetic and genomic analyses, along with bioassays and antibiotic susceptibility testing, revealed that the four strains, YY-01T, YY-02T, YY-03T and YY-04, represent three novel species within the genus Microbacterium. Phylogenetic reconstruction based on 16S rRNA gene sequences revealed the closest relatives as follows: strain YY-01T shares closest affinity with Microbacterium pseudoresistens CC-005209T (97.1% similarity), strains YY-02T and YY-04 cluster with Microbacterium esteraromaticum DSM 8609T (98.3–98.4% similarity) and strain YY-03T aligns with Microbacterium mitrae M4-8T (97.6% similarity). Genome phylogeny further resolved strain YY-01T as a sister lineage to Microbacterium laevaniformans DSM 20140T, while strains YY-02T, YY-03T and YY-04 exhibited phylogenetic relationships congruent with the 16S rRNA topology. Genomic relatedness analysis demonstrated that strains YY-02T and YY-04 share an OrthoANIu value of 99.9% and a digital DNA–DNA hybridization (dDDH) value of 100%, confirming their classification as conspecific. In contrast, OrthoANIu and dDDH values between strains YY-01T, YY-02T and YY-03T and other Microbacterium species were ≤82.1 and 28.3%, respectively, supporting their distinct species status. Chemotaxonomic analysis revealed distinct profiles for each strain. Strain YY-01T was characterized by MK-13 menaquinones; major fatty acids anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0; and the polar lipids diphosphatidylglycerol (DPG) and phosphatidylglycerol (PG). Strain YY-02T contained predominant menaquinones MK-11 and MK-13 and major fatty acids anteiso-C17 : 0, anteiso-C15 : 0 and iso-C16 : 0, along with DPG and PG. Strain YY-03T possessed major menaquinones MK-11 and MK-13; major fatty acids anteiso-C15 : 0, iso-C15 : 0 and iso-C16 : 0; and polar lipids DPG and PG. Integrative genomic, phenotypic and phylogenetic evidence supports the proposal of three novel species: Microbacterium luticellae sp. nov. (type strain YY-01T=GDMCC 1.5102T=KCTC 59478T), Microbacterium alcoholitolerans sp. nov. (type strain YY-02T=GDMCC 1.5103T=KCTC 59479T) and Microbacterium daqui sp. nov. (type strain YY-03T=GDMCC 1.5104T=KCTC 59480T).

A novel actinobacterial strain V21-05T was isolated from the thallus of the foliose lichen Heterodermia diademata collected in Doi Inthanon National Park, Chiang Mai Province, Thailand. Phylogenetic analysis based on the 16S rRNA gene and whole-genome sequences consistently placed strain V21-05T within the genus Streptosporangium, forming a well-supported clade with Streptosporangium oxazolinicum JCM 17388T. The draft genome of strain V21-05T contained 71.1 mol% of G+C content. Strain V21-05T exhibited digital DNA–DNA hybridization and average nucleotide identity values with S. oxazolinicum JCM 17388T below the species delineation thresholds. A polyphasic approach revealed differences in physiological characteristics, carbon and nitrogen utilization patterns and enzymatic activity profiles between V21-05T and the closely related strains. The chemotaxonomic characteristics supported its placement within the genus Streptosporangium, with meso-diaminopimelic acid, MK-9(H2) and MK-9(H4) as predominant menaquinones, and fatty acids including iso-C16:0, C17:1 ω8C, and C17:0 10-methyl. The polar lipid profile comprised phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, two unidentified glycolipids, two unidentified aminophospholipids and two unidentified phosphoglycolipids. These results support the classification of strain V21-05T as a representative of a novel species, for which the name Streptosporangium heterodermiicola sp. nov. (type strain =V21-05T =TBRC 20022T =NBRC 117251T) is proposed. This is the first report of a novel Streptosporangium from a lichen habitat.

Two strains, B21T and C4-1T, were obtained from soil near Sinpung Station, the Republic of Korea. The two aerobic, Gram-negative, rod-shaped bacterial strains were designated B21T and C4-1T. Phylogenetic tree analysis based on 16S rRNA and whole-genome sequences suggested that the strains B21T and C4-1T belonged to the genera Gordonia and Nocardioides, respectively. The draft genome of strain B21ᵀ consists of 4.99 Mb with a G+C content of 68.3 mol%, while that of strain C4-1ᵀ is 4.80 Mb with a 72.8 mol% G+C content. The cells of strain B21T were non-motile and grew at a temperature of 15–50 °C (optimum, 40 °C), in the presence of 0–11.0% (w/v) sodium chloride (NaCl) (optimum, 0.0%) and at pH 5.0–12.0 (optimum, 8.0). The cells of strain C4-1T were non-motile and grew at a temperature of 15–30 °C (optimum, 30 °C), in the presence of 0–8.0% (w/v) NaCl (optimum, 0%) and at pH 5.0–10.0 (optimum, 8.0). The novel strains B21T and C4-1T exhibited average nucleotide identity values of 73.9–87.2% and 75.0–81.4% and digital DNA–DNA hybridization values of 19.9–32.8% and 20.0–24.0%, with reference strains in the genera Gordonia and Nocardioides, respectively. We thus propose the names Gordonia aurantiaca (type strain B21T=KACC 23739T=TBRC 19009T) and Nocardioides secundeburneus (type strain C4-1T=KACC 23738T=TBRC 19008T).

Microcystis blooms deteriorate water quality and pose significant threats to aquatic ecosystems. Understanding how micro-organisms contribute to their formation is essential for developing effective control strategies. Although Flavobacterium species frequently coexist with Microcystis in natural environments, their role in Microcystis bloom formation remains largely unexplored. In the present study, a novel Gram-negative, designated strain RS13.1T, was isolated from freshwater during a Microcystis bloom. Phylogenetic analysis based on 16S rRNA gene sequences placed strain RS13.1ᵀ within the genus Flavobacterium, closely related to Flavobacterium limi THG-AG6.4ᵀ (98.89%) and Flavobacterium hibisci THG-HG1.4ᵀ (97.98%). The average nucleotide identity and digital DNA–DNA hybridization between strain RS13.1T and Flavobacterium species were below 89.39% and 37.60%, respectively. The growth of Microcystis increased by 26.6 % after 7 days when cultured with strain RS13.1ᵀ at 10% (v/v), demonstrating its growth-promoting effect. Furthermore, Microcystis exhibited tolerance to 20 mg l−1 H2O2, and its photosynthesis remained unaffected even with exposure to 5 mg l−1 H2O2 in the presence of RS13.1T. Genome annotation of strain RS13.1T revealed the presence of genes associated with carbohydrate-active enzyme, vitamin, heme and catalase biosynthesis, verifying mutualistic interaction between strain RS13.1T and Microcystis. Overall, these findings suggest that strain RS13.1T may contribute to the formation and persistence of Microcystis bloom by alleviating oxidative stress and supplying beneficial nutrients. Based on polyphasic features, strain RS13.1ᵀ was identified as a distinct species within the genus, for which the name Flavobacterium adiutor sp. nov. is proposed. The type strain is Flavobacterium adiutor RS13.1T (=KCTC 102193T=LMG 33484T).

Two Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacteria, designated strains S174ᵀ and W118ᵀ, were isolated from the marine green alga Ulva prolifera and the marine red alga Schizymenia dubyi, respectively, collected in South Korea. Both strains exhibited catalase- and oxidase-positive activities and grew optimally at 25 °C, pH 8.0 and 2.0% (w/v) NaCl. The major fatty acids (>10%) in both strains were iso-C15:1 G, iso-C15:0 and iso-C17:0 3-OH, with phosphatidylethanolamine as the major polar lipid and menaquinone-6 as the predominant respiratory quinone. The genomic DNA G+C contents, based on whole-genome sequences, were 39.1 mol% for both strains. Strains S174ᵀ and W118ᵀ shared 93.6% 16S rRNA gene sequence similarity, 72.7% average nucleotide identity (ANI) and 17.5% digital DNA–DNA hybridization (dDDH), supporting their classification as distinct species. Phylogenetic analyses based on 16S rRNA gene and genome sequences placed both strains in distinct lineages within the genus Flagellimonas. Strains S174ᵀ and W118ᵀ were most closely related to Flagellimonas meridianipacifica SW027ᵀ (97.2%) and Flagellimonas onchidii XY-359ᵀ (97.9%), respectively, and ANI and dDDH values with other type strains were below 84.6 and 28.2%, respectively, confirming their novelty. Based on phenotypic, chemotaxonomic and genomic features, strains S174ᵀ and W118ᵀ represent two novel species of the genus Flagellimonas, for which the names Flagellimonas ulvae sp. nov. (S174ᵀ=KACC 24029ᵀ=JCM 37803ᵀ) and Flagellimonas rhodophyticola sp. nov. (W118ᵀ=KACC 24030ᵀ=JCM 37802ᵀ) are proposed.

Bacteria involved in the anaerobic degradation of lignocellulosic waste in landfill sites play crucial roles in carbon turnover and biogas generation. In this study, we isolated and characterized a novel anaerobic bacterium, strain meth-B3ᵀ, from a laboratory-scale methanogenic bioreactor fed with maize-based biomass. Cells were Gram-stain-negative, non-spore-forming, motile rods with optimal growth at 35 °C, pH 7.0 and 0.7% sodium chloride (NaCl). Strain meth-B3ᵀ utilized a broad spectrum of carbohydrates, amino acids and organic acids, including glucose, cellobiose, glycerol, sucrose, maltose and various nitrogenous compounds. It fermented glucose into acetate, butyrate, lactate, propionate, valerate and ethanol. Whole-genome sequencing revealed a 3.8 Mbp genome with a G+C content of 62.65 mol%. Phylogenomic analyses based on 16S rRNA and conserved marker genes placed strain meth-B3ᵀ within the order Eubacteriales, forming a distinct clade from other known families. Comparative genomic metrics (average nucleotide identity, ≤69.4%; average amino acid identity, ≤54.2%; percentage of conserved protein, ≤35.2%) confirmed that strain meth-B3ᵀ represents a novel genus and family. Notably, carbohydrate-active enzyme and Clusters of Orthologous Groups (COG) functional profiling revealed an extensive suite of enzymes with potential activities against cellulose, xylan, starch and other maize-derived polymers, underscoring its ecological and biotechnological relevance in biomass degradation and biogas production. On the basis of genotypic and phenotypic distinctions, we propose the name Anaerozeibacter quisquiliarum gen. nov., sp. nov., with strain meth-B3ᵀ (=DSM 112769ᵀ=ATCC TSD-269ᵀ) being the type strain, and designate Anaerozeibacteraceae fam. nov. within the order Eubacteriales to accommodate this lineage.

A novel marine bacterium, strain LLJ827T, was isolated from deep-sea waters from the Yonaguni Knoll IV hydrothermal vent in the Okinawa Trough. This Gram-stain-negative, strictly aerobic, rod-shaped organism exhibits a growth temperature range of 20–45 °C, with the optimal growth at 28 °C. The strain thrives in pH conditions ranging from 5.0 to 8.0 (optimal at pH 6.0) and can tolerate NaCl concentrations of 3–10%. The predominant respiratory of strain LLJ827T was ubiquinone-10. The major fatty acids identified were summed feature 8 (comprising C18:1 ω7c and/or C18:1 ω6c) and C18:1 2-OH. The polar lipid profile included phosphatidylcholine (PC), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylmonomethylethanolamine (PME), along with several unidentified phospholipids (PL), aminolipids (AL), glycolipids (GL) and lipids (L). The 16S rRNA gene sequence of strain LLJ827T showed the closest similarity to Jiella avicenniae CBK1P-4T (98.06%), followed by other Jiella species. Phylogenetic analysis based on 16S rRNA gene sequences also showed that strain LLJ827T was clustered within the genus Jiella. The average nucleotide identity and DNA–DNA hybridization values of genomes of strain LLJ827T and J. avicenniae CBK1P-4T are 77.21 and 22.3%, respectively. The genomic G+C content of strain LLJ827T is 64.0 mol%. Strain LLJ827T has numbers of genes associated with carbohydrate metabolism, thiosulphate oxidation and [NiFe]-hydrogenases. Based on comprehensive polyphasic analysis, strain LLJ827T is proposed as a novel species within the Jiella genus, named Jiella marina sp. nov., with the type strain designated as LLJ827T (=MCCC 1K04957T=KCTC 82884T).

Three previously uncharacterized bacterial species, designated strains BD586T, BD613T and BD626T, isolated from human clinical specimens, were identified at Mayo Clinic, Rochester, Minnesota, USA. Initial identification efforts using matrix-assisted laser desorption ionization-time-of-flight MS and partial 16S rRNA gene sequencing proved inconclusive. Comprehensive analysis involving phenotypic characterization, biochemical assays and whole-genome sequencing was undertaken. The isolates were Gram-negative, motile, facultatively anaerobic rods, occurring singly, in pairs and in short chains; BD613T additionally formed small aggregates. The isolates tested positive for catalase and negative for oxidase. Their colonies appeared smooth, white, opaque and non-haemolytic. Growth was observed at 35 °C under aerobic, anaerobic and CO₂-enriched conditions, as well as in media with NaCl concentrations up to 10% and at pH 7-9. Phylogenetic relationships were inferred from core gene alignments, average nucleotide identity and digital DNA–DNA hybridization comparisons. Results confirmed the placement of BD586T, BD613T and BD626T within the recently established Dryocola genus, while also indicating their novelty as distinct species. The major cellular fatty acids were C16:0 and C17:0 cyclo. Based on these findings, a formal description of three new species, Dryocola mayonis sp. nov. (type strain BD586T=TSD 474T, =NCTC 15089T, =DSM 119465T), Dryocola sharpae sp. nov. (type strain BD613T=TSD 475T, =NCTC 15090T, =DSM 119466T) and Dryocola baronae sp. nov. (type strain BD626T=TSD 476T, =NCTC 15091T, =DSM 119479T), is proposed, and the genus description of Dryocola is emended to refine its genomic, morphological and chemotaxonomic boundaries.

A marine bacterium capable of degrading alginate, designated as strain TSD2052T, was isolated from a tidal flat sediment sample collected in Taean County, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain TSD2052T belonged to the genus Agarivorans, showing 96.2–97.8% sequence similarity. The whole genome of strain TSD2052T was 4.62 Mb, with a DNA G+C content of 44.3 mol%. The average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values between strain TSD2052T and all genome-sequenced species of the genus Agarivorans were below 76.7%, 81.7% and 20.6%, respectively, indicating values lower than the standard cut-off for species delineation. Growth was observed at 10–35 °C (optimum 25 °C), pH 6–10 (optimum pH 8) and 1–5% (w/v) NaCl (optimum 3%). The major fatty acids (>10%) were C12:0, C16:0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1ω7c) and summed feature 8 (C18 : 1 ω6c and/or C18:1ω7c). The respiratory quinone was ubiquinone-8. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid and four unidentified lipids. Based on the results of phenotypic characterization, phylogenetic analysis and genome-based comparisons, strain TSD2052T represents a novel species in the genus Agarivorans, for which we propose the name Agarivorans sediminis sp. nov. (=KCTC 92288T=JCM 35392T).

Two novel marine bacterial strains MAO6T and MAO7 having 12 different nucleotide sequences of 16S rRNA gene were isolated from surface water of a sandy beach located at the innermost part of Wakasa Bay in Fukui, Japan. The result of phylogenetic analysis based on 16S rRNA gene indicated that MAO6T clustered with the Agarivorans clade of the genus Vibrio. Closest relatives of the strain MAO6T were Vibrio agarivorans 289T and Vibrio astriarenae C7T with 16S rRNA gene sequence identities of 95.79–97.56 and 94.79–97.09%, respectively. A molecular network reconstructed on the basis of nucleotide sequences of four phylogenetic marker protein genes (ftsZ, mreB, pyrH and topA) revealed that the strains MAO6T and MAO7 were closely related to the type strains of Agarivorans clade species. Values of digital DNA–DNA hybridization and average nucleotide identity between both strains and type strains of Agarivorans clade were lower than the threshold for species delineation, indicating that these strains represent a novel species of the genus Vibrio. Cells were Gram-stain-negative, facultatively anaerobic, motile by means of a single polar flagellum and had a short rod shape with 0.7–1.5 µm in width and 2.2–6.3 µm in length. The strains grew under saline conditions at NaCl concentration of 0.5–6.0% (w/v), at temperature of 10(15)–35 °C and at pH (6.0)6.5–9.5(10.0). The most prevalent (>10%) cellular fatty acids of MAO6T and MAO7 were C16:0, summed feature 3 (C16:1  ω7c and C16:1  ω6c) and summed feature 8 (C18:1  ω7c or C18:1  ω6c). Based on their genetic and phenotypic features, the new isolates represent a novel species of the genus Vibrio for which the name Vibrio sabulosilitoris sp. nov. is proposed with type strain MAO6T (=BCRC 81474T=JCM 37826T).

During a survey of fungi in the Furna Nova cave of the Brazilian dry forest (Caatinga), two specimens of Circinella (URM 9081 and URM 9082) were isolated. Based on morphological and molecular data (ITS and LSU rDNA regions), a new species that is closely related to Circinella homothallica is delimited. The isolates form light grey to dark brown colonies and reverse yellowish. Dimorphic, short and tall sporangiophores are formed. Short sporangiophores are circinate, unbranched or sympodially branched, while the tall ones are erect, unbranched or simply branched, with some showing a swelling below apophyses. Sporangia of tall sporangiophores are deliquescent-walled, while the ones of short sporangiophores are persistent-walled. Sporangiospores are hyaline and elliptical, some with rounded ends. Zygosporangia are homothallic, yellow to brown, ornamented-walled, and suspensors are opposed and unequal in shape and size. This study contributes to the knowledge of Mucoromycota species in Brazilian caves.