Comparative pangenome analysis of Enterococcus faecium and Enterococcus lactis provides new insights into the adaptive evolution by horizontal gene acquisitions.

BACKGROUND: Enterococcus faecium and E. lactis are phylogenetically closely related lactic acid bacteria that are ubiquitous in nature and are known to be beneficial or pathogenic. Despite their considerable industrial and clinical importance, comprehensive studies on their evolutionary relationships and genomic, metabolic, and pathogenic traits are still lacking. Therefore, we conducted comparative pangenome analyses using all available dereplicated genomes of these species. RESULTS: E. faecium was divided into two subclades: subclade I, comprising strains derived from humans, animals, and food, and the more recent phylogenetic subclade II, consisting exclusively of human-derived strains. In contrast, E. lactis strains, isolated from diverse sources including foods, humans, animals, and the environment, did not display distinct clustering based on their isolation sources. Despite having similar metabolic features, noticeable genomic differences were observed between E. faecium subclades I and II, as well as E. lactis. Notably, E. faecium subclade II strains exhibited significantly larger genome sizes and higher gene counts compared to both E. faecium subclade I and E. lactis strains. Furthermore, they carried a higher abundance of antibiotic resistance, virulence, bacteriocin, and mobile element genes. Phylogenetic analysis of antibiotic resistance and virulence genes suggests that E. faecium subclade II strains likely acquired these genes through horizontal gene transfer, facilitating their effective adaptation in response to antibiotic use in humans. CONCLUSIONS: Our study offers valuable insights into the adaptive evolution of E. faecium strains, enabling their survival as pathogens in the human environment through horizontal gene acquisitions.

Chitinophaga pollutisoli sp. nov., isolated from contaminated sediment.

A Gram-stain-negative, yellow-pigmented, and facultatively aerobic bacterium, designated strain GPA1T, was isolated from plastic waste landfill soil in the Republic of Korea. The cells were non-motile short rods exhibiting oxidase-negative and catalase-positive activities. Growth was observed at 15-40 °C (optimum, 30 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 0-2.5 % (w/v) NaCl (optimum, 0 %). Menaquinone-7 was the sole respiratory quinone, and iso-C15 : 0, C16 : 1 ω5c, and iso-C17 : 0 3-OH were the major cellular fatty acids (>10 % of the total fatty acids). Phosphatidylethanolamine was identified as a major polar lipid. Phylogenetic analyses based on 16S rRNA gene sequences and 120 concatenated marker protein sequences revealed that strain GPA1T formed a distinct lineage within the genus Chitinophaga. The genome of strain GPA1T was 6078 kb in size with 53.8 mol% G+C content. Strain GPA1T exhibited the highest similarity to Chitinophaga rhizosphaerae T16R-86T, with a 98.6 % 16S rRNA gene sequence similarity, but their average nucleotide identity and digital DNA-DNA hybridization values were 82.5 and 25.9 %, respectively. Based on its phenotypic, chemotaxonomic, and phylogenetic characteristics, strain GPA1T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga pollutisoli sp. nov. is proposed. The type strain is GPA1T (=KACC 23415T=JCM 36644T).

Marinomonas rhodophyticola sp. nov. and Marinomonas phaeophyticola sp. nov., isolated from marine algae.

Two Gram-stain-negative, facultatively aerobic, and motile rod bacteria, designated as strains KJ51-3T and 15G1-11T, were isolated from marine algae collected in the Republic of Korea. Both strains exhibited catalase- and oxidase-positive activities. Optimum growth conditions for strain KJ51-3T were observed at 30 °C and pH 6.0-8.0, with 1.0-7.0 % (w/v) NaCl, whereas strain 15G1-11T exhibited optimal growth at 30 °C, pH 7.0, and 1.0-5.0 % NaCl. Major fatty acids detected in both strains included C16 : 0, C10 : 0 3-OH and summed features 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). As for polar lipids, strain KJ51-3T contained phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol, and two unidentified phospholipids, whereas strain 15G1-11T had PE, PG, and an unidentified aminolipid. Ubiquinone-8 was the predominant respiratory quinone in both strains, with minor detection of ubiquinone-9 in strain KJ51-3T. The genomic DNA G+C contents were 44.0 mol% for strain KJ51-3T and 40.5 mol% for strain 15G1-11T. Phylogenetic analyses based on both 16S rRNA gene and genome sequences placed strains KJ51-3T and 15G1-11T into distinct lineages within the genus Marinomonas, most closely related to Marinomonas arctica 328T (98.6 %) and Marinomonas algicola SM1966T (98.3 %), respectively. Strains KJ51-3T and 15G1-11T exhibited a 94.6 % 16S rRNA gene sequence similarity and a 70.7 % average nucleotide identity (ANI), with ANI values of 91.9 and 79.3 % between them and M. arctica 328T and M. algicola SM1966T, respectively, indicating that they represent novel species. In summary, based on their phenotypic, chemotaxonomic, and phylogenetic properties, strains KJ51-3T and 15G1-11T are proposed to represent novel species within the genus Marinomonas, for which the names Marinomonas rhodophyticola sp. nov. (KJ51-3T=KACC 22756T=JCM 35591T) and Marinomonas phaeophyticola sp. nov. (15G1-11T=KACC 22593T=JCM 35412T) are respectively proposed.

Devosia rhodophyticola sp. nov. and Devosia algicola sp. nov., isolated from a marine red alga.

Two Gram-stain-negative, obligately aerobic, motile rod bacteria, designated as G2-5T and G20-9T, exhibiting catalase- and oxidase-positive activities, were isolated from the phycosphere of a Chondrus species, a marine red alga. Strain G2-5T exhibited optimal growth at 30 °C and pH 5.0-6.0 and in the presence of 0.5-1.0% NaCl. In contrast, strain G20-9T demonstrated optimal growth at 25 °C and pH 6.0 and in the presence of 0.5-1.5% NaCl. Both strains contained ubiquinone-10, summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C18 : 0 and 11-methyl-C18 : 1 ω7c, and diphosphatidylglycerol and phosphatidylglycerol as the major respiratory isoprenoid quinone, cellular fatty acids and polar lipids, respectively. The genomic DNA G+C contents were 57.2 mol% for strain G2-5T and 57.5 mol% for strain G20-9T. Strains G2-5T and G20-9T exhibited 98.2 % 16S rRNA gene sequence similarity, along with 82.3 % average nucleotide identity (ANI) and 25.0 % digital DNA-DNA hybridization (dDDH) values, indicating that they represent different species. Phylogenetic analyses based on both 16S rRNA gene and genome sequences revealed that strains G2-5T and G20-9T formed distinct phylogenic lineages within the genus Devosia. Strains G2-5T and G20-9T were most closely related to Devosia limi DSM 17137T and Devosia beringensis S02T with 97.7 and 96.9 % 16S rRNA gene sequence similarities, respectively. The ANI and dDDH values between strains G2-5T and G20-9T and other Devosia species were lower than 73.9 and 19.2 %, respectively, suggesting that they constitute novel species within the genus Devosia. Based on their distinct phenotypic, chemotaxonomic, and molecular characteristics, strains G2-5T and G20-9T represent two novel species of the genus Devosia, for which the names Devosia rhodophyticola sp. nov. (G2-5T=KACC 22601T=JCM 35404T) and Devosia algicola sp. nov. (G20-9T=KACC 22650T=JCM 35405T) are proposed, respectively.

Roseibium algicola sp. nov. and Roseibium porphyridii sp. nov., isolated from marine red algae.

Two Gram-stain-negative, strictly aerobic rods, designated as RMAR6-6T and KMA01T, exhibiting catalase- and oxidase-positive activities, were isolated from marine red algae in the Republic of Korea. Cells of strain RMAR6-6T exhibited flagellar motility, while those of strain KMA01T were non-motile. Strain RMAR6-6T exhibited optimal growth at 30-35°C and pH 7.0-8.0 with 4.0-6.0 % (w/v) NaCl, while strain KMA01T grew optimally at 30-35 °C, pH 7.0-8.0 and 2.0-5.0% NaCl. Both strains shared common major respiratory isoprenoid quinone (ubiquinone-10), cellular fatty acids (C18 : 0, C18: 1 ω7c 11-methyl, C20 : 1 ω7c and summed feature 8) and polar lipids (phosphatidylglycerol, phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and sulphoquinovosyldiacylglycerol). The genomic DNA G+C contents were 59.0 and 55.0 mol% for strains RMAR6-6T and KMA01T, respectively. With 98.5 % 16S rRNA gene similarity, 75.2 % average nucleotide identity (ANI) and 19.8 % digital DNA-DNA hybridization (dDDH) values, strains RMAR6-6T and KMA01T were identified as representing distinct species. Phylogenetic analyses based on both 16S rRNA gene and genome sequences revealed that strains RMAR6-6T and KMA01T formed distinct phylogenic lineages within the genus Roseibium, most closely related to Roseibium aggregatum IAM 12614T and Roseibium album CECT 5094T, respectively. The ANI and dDDH values between strain RMAR6-6T and R. aggregatum IAM 12614T were 87.5 and 33.3 %, respectively. Similarly, the values between KMA01T and R. album CECT 5094T were 74.2 % (ANI) and 19.3 % (dDDH). Based on phenotypic, chemotaxonomic and molecular characteristics, strains RMAR6-6T and KMA01T represent two novel species of the genus Roseibium, for which the names R. algicola sp. nov. (RMAR6-6T=KACC 22482T=JCM 34977T) and R. porphyridii sp. nov. (KMA01T=KACC 22479T=JCM 34597T) are proposed, respectively.

Comparative pangenome analysis of Aspergillus flavus and Aspergillus oryzae reveals their phylogenetic, genomic, and metabolic homogeneity.

Aspergillus flavus and Aspergillus oryzae are closely related fungal species with contrasting roles in food safety and fermentation. To comprehensively investigate their phylogenetic, genomic, and metabolic characteristics, we conducted an extensive comparative pangenome analysis using complete, dereplicated genome sets for both species. Phylogenetic analyses, employing both the entirety of the identified single-copy orthologous genes and six housekeeping genes commonly used for fungal classification, did not reveal clear differentiation between A. flavus and A. oryzae genomes. Upon analyzing the aflatoxin biosynthesis gene clusters within the genomes, we observed that non-aflatoxin-producing strains were dispersed throughout the phylogenetic tree, encompassing both A. flavus and A. oryzae strains. This suggests that aflatoxin production is not a distinguishing trait between the two species. Furthermore, A. oryzae and A. flavus strains displayed remarkably similar genomic attributes, including genome sizes, gene contents, and G + C contents, as well as metabolic features and pathways. The profiles of CAZyme genes and secondary metabolite biosynthesis gene clusters within the genomes of both species further highlight their similarity. Collectively, these findings challenge the conventional differentiation of A. flavus and A. oryzae as distinct species and highlight their phylogenetic, genomic, and metabolic homogeneity, potentially indicating that they may indeed belong to the same species.

Neobacillus terrae sp. nov., isolated from mountain soil.

A Gram-stain-positive, spore-forming and facultative aerobic bacterium, designated C11T, was isolated from mountain soil collected in the Republic of Korea. The cells were motile rods with peritrichous flagella, and positive for catalase and oxidase activities. Strain C11T grew at 15-45 °C (optimum, 30-37 °C) and pH 6.0-8.0 (optimum, pH 6.0) and in the presence of 0-1 % (w/v) NaCl (optimum, 0.5 %). Strain C11T contained menaquinone-7 as the sole isoprenoid quinone and iso-C15 : 0, iso-C16 : 0 and anteiso-C15 : 0 as the major fatty acids. Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were the major polar lipids. The G+C content of the genomic DNA was 38.8 mol%. Strain C11T was most closely related to Neobacillus drentensis IDA1967T and Mesobacillus foraminis CV53T, with 98.0 and 97.7 %, 71.7 and 69.9 %, and 20.1 and 20.3 % 16S rRNA gene sequence similarity, average nucleotide identity, and digital DNA-DNA hybridization values, respectively. Phylogenetic analyses based on 16S rRNA gene and genome sequences showed that strain C11T was included in a phyletic lineage with members of the genus Neobacillus but was distinct from members of the genus Mesobacillus. Phenotypic, chemotaxonomic and molecular properties suggested that strain C11T represents a novel species of the genus Neobacillus, for which the name Neobacillus terrae sp. nov. is proposed. The type strain is C11T (=KACC 21661T=JCM 33943T).

Octadecabacter algicola sp. nov. and Octadecabacter dasysiphoniae sp. nov., isolated from a marine red alga and emended description of the genus Octadecabacter.

Two Gram-stain-negative, strictly aerobic, catalase- and oxidase-positive and non-motile rod-shaped bacteria, strains D2-3T and G9-8T, were isolated from a marine red alga. Both strains contained ubiquinone-10 as the sole isoprenoid quinone. As the major cellular fatty acids (>5.0 %), D2-3T contained C16 : 0, 11-methyl-C18 : 1ω7c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), whereas G9-8T contained C16 : 0, 11-methyl-C18 : 1ω7c, C12 : 1 3-OH, and summed feature 8. The DNA G+C contents of D2-3T and G9-8T were 54.4 % and 56.0 %, respectively. As the major polar lipids, phosphatidylglycerol, diphosphatidylglycerol and unidentified phospholipid, aminolipid and lipid were identified from both strains, and phosphatidylcholine was additionally detected from G9-8T only. The 16S rRNA gene sequence similarity of D2-3T and G9-8T was 98.5 % and their digital DNA-DNA hybridization (DDH) value was 19.1 %. Phylogenetic analyses based on 16S rRNA gene and genome sequences revealed that D2-3T and G9-8T formed respectively distinct phylogenetic lineages within the genus Octadecabacter. D2-3T and G9-8T were most closely related to Octadecabacter ascidiaceicola RA1-3T and Octadecabacter antarcticus 307T, with 98.9 % and 98.5 % 16S rRNA gene sequence similarities, respectively, and digital DDH values between D2-3T and O. ascidiaceicola and between G9-8T and O. antarcticus were 18.3 % and 19.5 %, respectively. Phenotypic, chemotaxonomic and molecular features support the hypothesis that D2-3T and G9-8T represent two novel species of the genus Octadecabacter, for which the names Octadecabacter algicola sp. nov. and Octadecabacter dasysiphoniae sp. nov. are proposed. The type strains of O. algicola and O. dasysiphoniae are D2-3T (=KACC 22493T =JCM 34969T) and G9-8T (=KACC 22488T =JCM 34973T), respectively.

Tahibacter soli sp. nov., isolated from soil and Tahibacter amnicola sp. nov., isolated from freshwater.

Two Gram-stain-negative, facultative aerobic, catalase- and oxidase-positive, and non-motile rod bacteria, strains BLT and W38T, that were isolated from soil and freshwater, respectively, were taxonomically characterized. Both strains optimally grew at 30 °C and pH 7.0 in Reasoner's 2A medium and contained ubiquinone-8 as the sole respiratory quinone. As major fatty acids (>10 %), strain BLT contained iso-C15 : 0 and summed features 3 and 9 (comprising iso-C15 : 0 2-OH and/or C16 : 1 ω7c/ω6c and iso-C17 : 1 ω9c and/or C16 : 0 10-methyl, respectively), whereas strain W38T contained iso-C15 : 0, iso-C16 : 0 and summed feature 9. Diphosphatidylglycerol and phosphatidylmonomethylethanolamine as major polar lipids and phosphatidylethanolamine and phosphatidylglycerol as minor polar lipids were detected in both strains. The DNA G+C contents of strains BLT and W38T were 68.3 and 65.3 %, respectively. Phylogenetic analyses based on 16S rRNA gene and genome sequences revealed that strains BLT and W38T formed a tight phylogenetic lineage with Tahibacter species, and they shared 98.8 % 16S rRNA gene sequence similarity and 75.5 % average nucleotide identity (ANI) and 16.6 % digital DNA-DNA hybridization (dDDH) values, indicating that they are different species. Strains BLT and W38T were most closely related to Tahibacter caeni BUT-6T and Tahibacter aquaticus PYM5-11T with 97.7 and 98.0 % 16S rRNA gene sequence similarities, respectively. ANI and dDDH values between strain BLT and T. caeni BUT-6T and between strain W38T and T. aquaticus DSM 21667T were 78.5 and 21.6% and 75.3 and 21.0 %, respectively. Based on their phenotypic, chemotaxonomic and genomic properties, strains BLT and W38T represent two different novel species of the genus Tahibacter, for which the names Tahibacter soli sp. nov. and Tahibacter amnicola sp. nov. are proposed. The type strains of T. soli and T. amnicola are BLT (=KACC 22831T=JCM 35402T) and W38T (=KACC 22832T=JCM 35749T), respectively.

Hoeflea algicola sp. nov. and Hoeflea ulvae sp. nov., isolated from phycosphere of marine algae.

Two Gram-negative, moderately halophilic, and motile rod bacteria, strains G2-23T and J2-29T, showing catalase- and oxidase-positive activities were isolated from species of the marine algae Chondrus and Ulva, respectively. Both strains optimally grew at 30 °C, pH 7.0 and 2% (w/v) NaCl. Both strains contained ubiquinone-10 as the sole isoprenoid quinone. Strain G2-23T contained summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C16 : 0 and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c/ω6c) as major cellular fatty acids, and phosphatidylethanolamine (PE), phosphatidyl-N-monomethylethanolamine (PME), phosphatidylglycerol (PG), diphosphatidylglycerol and an unidentified phospholipid (PL) as major polar lipids. Strain J2-29T contained summed feature 8, C18 : 1 ω7c 11-methyl and C16 : 0 as major cellular fatty acids and PE, PME, PG and PL as major polar lipids. The genomic DNA G+C contents of strains G2-23T and J2-29T were 59.5 and 62.2 mol%, respectively. Both strains shared 97.9 % 16S rRNA gene sequence similarity, 79.8 % average nucleotide identity (ANI) and 22.8 % digital DNA-DNA hybridization (dDDH) values, indicating that they represent different species. Phylogenetic and phylogenomic analyses by 16S rRNA gene and genome sequences, respectively, revealed that strains G2-23T and J2-29T formed different phylogenic lineages within the genus Hoeflea. ANI and dDDH values between strains G2-23T and J2-29T and other Hoeflea type strains were less than 79.0 and 22.1% and 80.5 and 23.3 %, respectively, suggesting that they represent novel species of the genus Hoeflea. In summary, based on their phenotypic, chemotaxonomic and molecular properties, strains G2-23T and J2-29T represent two different novel species of the genus Hoeflea, for which the names Hoeflea algicola sp. nov. (G2-23T=KACC 22714T=JCM 35548T) and Hoeflea ulvae sp. nov. (J2-29T=KACC 22715T=JCM 35549T), respectively, are proposed.

Chitinophaga horti sp. nov., Isolated from Garden Soil.

A strictly aerobic Gram-negative bacterium, designated R8T, isolated from garden soil in South Korea was subjected to a taxonomic study. The cells were non-spore-forming, oxidase-positive and catalase-negative, and non-motile rods (without flagella). Growth was observed between 10 °C and 40 °C (optimum, 30 °C) and between pH 6.0 and 9.0 (optimum, pH 7.0) and in the presence of 0%-1.5% (w/v) NaCl (optimum, 0%). The G + C content of the genomic DNA was 49.9% and the major isoprenoid quinone was found to be menaquinone-7. The major fatty acids of strain R8T were iso-C15:0, C16:1 ω5c, and summed feature 3 (comprising iso-C15:0 2-OH and/or C16:1 ω7c/ω6c). Phosphatidylethanolamine was identified as a major polar lipid. Comparative 16S rRNA gene sequence analysis showed that strain R8T had the highest 16S rRNA gene sequence similarity of 98.3% with Chitinophaga sedimenti TFL-3 T. Phylogenetic analyses using 16S rRNA gene sequences and concatenated 92 marker protein sequences revealed that strain R8T formed a robust phylogenetic lineage with C. sedimenti within the genus Chitinophaga. Average nucleotide identity and digital DNA-DNA hybridization values of strain R8T to Chitinophaga species were less than 77.9% and 21.1%, respectively. The phenotypic, phylogenetic, and chemotaxonomic properties support that strain R8T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga horti sp. nov. is proposed. The type strain is R8T (= KACC 19895 T = JCM 33215 T).

Fermentative features of Bacillus velezensis and Leuconostoc mesenteroides in doenjang-meju, a Korean traditional fermented soybean brick.

To investigate the fermentative characteristics of Bacillus and lactic acid bacteria, the key microbes known to be involved in doenjang-meju (a Korean traditional fermented soybean brick) fermentation, we prepared and analyzed two sets of doenjang-meju inoculated with either Aspergillus oryzae and Bacillus velezensis (BDM) or A. oryzae and Leuconostoc mesenteroides (LDM). A large decrease in pH was observed during the early fermentation period in LDM, whereas the pH remained relatively constant in BDM. Although observed in higher levels in BDM during the early fermentation period, free sugar and amino acid contents and Aspergillus abundance were higher in LDM thereafter, which aligned with α-amylase and protease activity profiles in LDM and BDM, suggesting their association with Aspergillus. Higher levels of isoflavone aglycones and glycerol along with greater ß-glucosidase and lipase activities in LDM and BDM, respectively, were suggestive of the characteristics of Leuconostoc and Bacillus, respectively. More diverse and higher amounts of volatile compounds were observed in BDM than in LDM. The α-amylase, lipase, protease, ß-glucosidase, and antimicrobial activities of A. oryzae, B. velezensis, and L. mesenteroides were examined through genomic analyses and in vitro assays, which well supported the results of their fermentative characteristics in LDM and BDM.

Rheinheimera maricola sp. nov., isolated from seawater of the Yellow Sea.

A Gram-negative and facultative aerobic strain, designated as strain MA-13T, was isolated from seawater in the Yellow Sea Republic of Korea. Cells were oxidase- and catalase-positive and non-motile short rods. Growth of strain MA-13T was observed over a range of 10-37 °C (optimum, 30 °C), pH 6.0-11.0 (optimum, pH 7.0) and in the presence of 0-5.5 % (w/v) sodium chloride (optimum, 1.0-2.0 %). Strain MA-13T contained ubiquinone-8 as the respiratory quinone, phosphatidylethanolamine, an unidentified aminolipid, an unidentified phospholipid and four unidentified lipids as major polar lipids and C16 : 0, C12 : 0 3-OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) as major cellular fatty acids. The G+C content of the genomic DNA was 48.3 mol%. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strain MA-13T formed a distinct phyletic lineage in the genus Rheinheimera. Strain MA-13T was most closely related to Rheinheimera lutimaris YQF-2T, Rheinheimera aquimaris SW-353T, Rheinheimera pacifica KMM 1406T and Rheinheimera baltica DSM 14885T with 98.10, 98.08, 98.07 and 97.94 % 16S rRNA gene sequence similarities. Average nucleotide identity and DNA-DNA hybridization values between strain MA-13T and R. aquimaris KCTC 12840T, R. pacifica DSM 17616T and R. baltica DSM 14885T were 76.3, 78.6 and 76.9 % and 19.5, 21.3 and 20.5 %, respectively. Based on the phenotypic, chemotaxonomic and molecular features, strain MA-13T represents a novel species of the genus Rheinheimera, for which the name Rheinheimera maricola sp. nov. is proposed. The type strain is MA-13T (=KACC 22113T=JCM 34600T).

Rhodococcus oxybenzonivorans sp. nov., a benzophenone-3-degrading bacterium, isolated from stream sediment.

A Gram-stain-positive, facultative aerobic, oxidase-negative, catalase-positive, non-sporulating, and non-motile bacterium, which degraded benzophenone-3, was isolated from stream sediment collected in the Republic of Korea and designated as strain S2-17T. Cells of this strain were rod-shaped during the early growth phase but became coccoid after the late exponential growth phase. Bacterial growth was observed at 15-37 °C (optimum, 25-30 °C) and pH 6.0-9.5 (optimum, pH 7.5-8.5) and in the presence of 0-9.0 % (w/v) NaCl (optimum, 0-1.0 %). Menaquinone-8 (H2) was the sole isoprenoid quinone, and C16 : 0, C17 : 1 ω8c, summed feature 3 (comprising C16 : 1 ω7c/C16 : 1 ω6c) and C18 : 1 ω9c were the major fatty acids. The cell wall of strain S2-17T contained meso-diaminopimelic acid, and arabinose, galactose and mycolic acid were found in whole-cell hydrolysates, suggesting a chemotype IV cell wall. The G+C content of the genome was 65.6 mol%. Phylogenetic analyses revealed that strain S2-17T formed a phyletic lineage within the genus Rhodococcus and was most closely related to Rhodococcus jostii DSM 44719T (99.2 % 16S rRNA gene sequence similarity). Average nucleotide identity and digital DNA-DNA hybridization values between strain S2-17T and R. jostii DSM 44719T were 82.6 and 26.5 %, respectively, indicating differences between the species. Based on its phenotypic, chemotaxonomic and molecular features, strain S2-17T represents a novel species of the genus Rhodococcus, for which the name Rhodococcus oxybenzonivorans sp. nov. is proposed. The type strain is S2-17T (=KACC 19281T=JCM 32046T).

Massilia soli sp. nov., isolated from soil.

A Gram-stain-negative, catalase- and oxidase-positive and aerobic bacterium, designated strain R798T, was isolated from soil in South Korea. Cells were motile rods by means of a single polar flagellum. Growth of strain R798T was observed at 15-35 °C (optimum, 25-30 °C), pH 5.0-8.0 (optimum, 6.0) and 0-1.5 % NaCl (optimum, 0.3 %). Strain R798T contained ubiquinone-8 as the sole isoprenoid quinone, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and C16 : 0 as the major fatty acids and phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. The DNA G+C content of strain R798T calculated from the whole genome sequence was 63.3 mol%. Phylogenetic analyses based on the 16S rRNA gene and whole genome sequences revealed that strain R798T formed a distinct phyletic lineage within the genus Massilia. Strain R798T was most closely related to Massilia eurypsychrophila B528-3T with a 98.0 % 16S rRNA gene sequence similarity. Average nucleotide identity and digital DNA-DNA hybridization values between strain R798T and the type strain of M. eurypsychrophila were 79.2 and 22.7 %, respectively. Based on the phenotypic, chemotaxonomic and molecular analyses, strain R798T represents a novel species of the genus Massilia, for which the name Massilia soli sp. nov. is proposed. The type strain is R798T (=KACC 22114T=JCM 34601T).

Microvirga terrae sp. nov., Isolated from Soil.

A Gram-stain-negative and strictly aerobic bacterium, strain R24T, was isolated from soil in South Korea. Cells were non-motile short rods showing catalase- and oxidase-positive activities. Growth was observed at 15-40 °C (optimum, 25-30 °C) and pH 6.0-10.0 (optimum, 8.0-9.0), and in the presence of 0-3.0% NaCl (optimum, 0%). Strain R24T contained ubiquinone-10 as the sole respiratory quinone, C16:0, C18:0, and summed feature 8 (comprising C18:1 ω7c and/or C18:1 ω6c) as the major fatty acids, and phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylcholine as the major polar lipids. The DNA G+C content calculated from the whole genome sequence was 64.4%. Strain R24T was most closely related to Microvirga aerilata 5420S-16T with a 98.6% 16S rRNA gene sequence similarity. Average nucleotide identity and digital DNA-DNA hybridization values between strain R24T and all Microvirga species were less than 82.5 and 23.8%, respectively. Phylogenetic analyses based on the 16S rRNA gene and whole genome sequences revealed that strain R24T formed a phyletic lineage within the genus Microvirga. Based on its phenotypic, chemotaxonomic, and molecular characteristics, strain R24T represents a novel species of the genus Microvirga, for which the name Microvirga terrae sp. nov. is proposed. The type strain is R24T (= KACC 21784T = JCM 34259T).

Paenibacillus agri sp. nov., isolated from soil.

A strict aerobic bacterium, strain JW14T was isolated from soil in the Republic of Korea. Cells were Gram-stain-positive, non-endospore-forming and motile rods showing catalase-positive and oxidase-negative activities. Growth of strain JW14T was observed at 20-37 °C (optimum, 30 °C), pH 6.0-10.0 (optimum, pH 7.0) and in the presence of 0-2.0% NaCl (optimum, 0%). Strain JW14T contained menaquinone-7 as the sole isoprenoid quinone, anteiso-C15:0, C16:0 and iso-C16 : 0 as the major fatty acids (>10.0%), and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified aminophospholipids and an unidentified lipid as the major polar lipids. The cell-wall peptidoglycan of strain JW14T contained meso-diaminopimelic acid. The DNA G+C content of strain JW14T calculated from the whole genome sequence was 48.1 mol%. Strain JW14T was most closely related to Paenibacillus graminis DSM 15220T with 97.4% 16S rRNA gene sequence similarity. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain JW14T formed a distinct phyletic lineage from closely related type strains within the genus Paenibacillus. Based on the results of phenotypic, chemotaxonomic and molecular analyses, strain JW14T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus agri sp. nov. is proposed. The type strain is JW14T (=KACC 21840T=JCM 34279T).

Paenibacillus silvestris sp. nov., Isolated from Forest Soil.

A bacterial strain, designated 5J-6T, was isolated from soil in Cheongnyeongpo, Republic of Korea. Cells were Gram-stain-positive, strictly aerobic, and motile rods and their catalase and oxidase activities were positive. Strain 5J-6T grew at 10-30 °C, pH 6.0-9.0, and 0-0.8% (w/v) NaCl concentration, with optimum growth at 25 °C, pH 6.5, and 0.4% NaCl concentration. Anteiso-C15:0 and iso-C16:0 were detected as the predominant fatty acids and menaquinone-7 was the sole isoprenoid quinone detected. Strain 5J-6T contained phosphatidylethanolamine, phosphatidylglycerol and an unidentified phospholipid as major polar lipids. The peptidoglycan belonged to the type A1γ meso-diaminopimelic acid. The G+C content of the genomic DNA calculated from the whole genomic sequence was 46.1 mol%. Phylogenetic analysis of strain 5J-6T based on 16S rRNA gene sequences placed the isolate into a member of the genus Paenibacillus. Sequence similarity analysis of 16S rRNA gene sequences revealed that strain 5J-6T was most closely related to Paenibacillus aceris KUDC4121T and Paenibacillus chondroitinus DSM 5051T with 98.76% and 98.42% similarities, respectively. Average nucleotide identity and in silico DNA-DNA hybridization values between strain 5J-6T and the type strain of P. aceris were 83.97% and 28.60%, respectively. Based on the phylogenetic and phenotypic characteristics and genomic data, strain 5J-6T could be considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus silvestris sp. nov. is proposed. The type strain is 5J-6T (= KACC 21430T = JCM 33812T).

Maribacter algicola sp. nov., isolated from a marine red alga, Porphyridium marinum, and transfer of Maripseudobacter aurantiacus Chen et al. 2017 to the genus Maribacter as Maribacter aurantiacus comb. nov.

A Gram-stain-negative, strictly aerobic and moderately halophilic bacterial strain, designated strain PoM-212T, was isolated from a marine alga, Porphyridium marinum, in the Republic of Korea. Cells were catalase- and oxidase-positive rods with gliding motility without flagellum. Growth was observed at 20-40 °C (optimum, 30 °C) and pH 5.0-8.5 (pH 5.0-5.5) and in the presence of 0.5-5 % (w/v) NaCl (2-3 %). Strain PoM-212T contained iso-C15 : 1, iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) as major fatty acids and menaquinone-6 as the sole isoprenoid quinone. Phosphatidylethanolamine, three unidentified aminolipids and two unidentified polar lipids were detected as major polar lipids. The G+C content of the genomic DNA was 41.0 mol%. Strain PoM-212T was most closely related to Maribacter lutimaris KJ4T, Maripseudobacter aurantiacus CDA4T and Maribacter flavus C3T with 97.2, 97.2 and 97.0 % 16S rRNA gene sequence similarities, respectively, and it formed a distinct phylogenetic lineage from them within the genus Maribacter. Maripseudobacter aurantiacus formed a close phylogenetic lineage with Maribacter flavus with 99.7 % 16S rRNA gene sequence similarity, but their digital DNA-DNA hybridization value was 67.4 %. On the basis of its phenotypic, chemotaxonomic and molecular properties, strain PoM-212T represents a novel species of the genus Maribacter, for which the name Maribacter algicola sp. nov. is proposed. The type strain is PoM-212T (=KACC 19789T=JCM 32941T). The transfer of Maripseudobacter aurantiacus to the genus Maribacter as Maribacter aurantiacus comb. nov. is also proposed (type strain CDA4T=KCTC 52409T=MCCC 1K03210T).

Acetobacter oryzoeni sp. nov., isolated from Korean rice wine vinegar.

A Gram-stain-negative, obligately aerobic bacterium, designated strain B6T, was isolated from rice wine vinegar in the Republic of Korea. Cells were non-motile and oval short rods showing catalase-positive and oxidase-negative activities. Growth was observed at 15-45 °C (optimum, 30 °C) and pH 3.5-8.0 (optimum, pH 5.5-6.5). Strain B6T contained summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1 ω6c), and C16 : 0 as major fatty acids and ubiquinone-9 was identified as the sole isoprenoid quinone. The G+C content of the genomic DNA calculated from the whole genome was 53.1 mol%. Strain B6T was most closely related to Acetobacter pasteurianus LMG 1262T with very high 16S rRNA gene sequence similarity (100 %) and the strains formed a very close phylogenetic lineage together in phylogenetic trees based on 16S rRNA gene sequences. However, relatedness analyses based on concatenated amino acid sequences of 354 core genes and whole-cell MALDI-TOF profiles showed that strain B6T may form a distinct phyletic lineage from Acetobacter species. In addition, average nucleotide identity and in silico DNA-DNA hybridization values between strain B6T and the type strains of Acetobacter species were less than 93.3 and 51.4 %, respectively. The genomic features of strain B6T were also differentiated from those of closely related Acetobacter type strains. Based on the phenotypic, chemotaxonomic and genomic features, strain B6T clearly represents a novel species of the genus Acetobacter, for which the name Acetobacter oryzoeni sp. nov. is proposed. The type strain is B6T (=KACC 21201T=JCM 33371T).