Hymenobacter roseosalivarius gen. nov., sp. nov. from continental Antartica soils and sandstone: bacteria of the Cytophaga/Flavobacterium/Bacteroides line of phylogenetic descent

Intrathalline Fungal and Bacterial Diversity Is Uncovered in Antarctic Lichen Symbioses

Although the Antarctic continent represents one of the most hostile environments on earth, microbial life has adapted to cope with these extreme conditions. Lichens are one of the most successful groups of organisms in Antarctica, where they serve as unique niches for microbial diversification. We have selected eight epilithic lichen species growing in Victoria Land (three cosmopolitan and five endemic to Antarctica) to describe with amplicon sequencing the diversity of the associated fungal and bacterial communities. The lichen mycobiota is predominantly composed of Ascomycota belonging to the classes Chaetothyriomycetes and Dothideomycetes, while a few key representative taxa were recognised as basidiomycetous yeasts. Bacteria associated with lichens were represented by Pseudomonadota, Cyanobacteria, and Bacteroidota in which psychrophilic genera were identified. The microbiota was diverse among the lichen species, and their variation was driven by the lichen species itself and their endemic or cosmopolitan distribution. There was a strong association of the microbial communities linked to the lichen itself, rather than to the specific characteristics of the collecting site. The lichen thallus, thus, plays an important role in microbial diversification and may potentially act as a selective biodiversity filter in which different fungal and bacterial communities thrive in it.

Bioprospecting Antarctic Microorganisms: Investigating Hymenobacter psoromatis PAMC26554 for Biochemical Potential

Microorganisms from the genus Hymenobacter are known for their distinctive traits, yet their secondary metabolite (SM) production has not been thoroughly investigated. In this study, we examined the biosynthetic potential of SMs from Hymenobacter psoromatis PAMC26554, which was isolated from Antarctic lichen. In silico analysis identified biosynthetic gene clusters (BGCs) for terpenes, non-ribosomal peptide synthetases (NRPSs), and polyketide synthases (PKSs), indicating the strain's potential for novel SM production. Optimization of culture conditions showed that R2A medium at 15°C supported growth. HPLC analysis revealed phenylacetic acid (PAA) as a notable compound, which was characterized by ESI-MS and NMR, marking the first isolation of PAA from the genus Hymenobacter. In addition, bioactivity assays indicated moderate lipase inhibition by PAA, while molecular docking studies revealed stable interactions with the enzyme, demonstrating that hydrogen bonding and π-π stacking contribute to its lipase inhibitory activity. In summary, this research highlights the genus Hymenobacter as a potential source for secondary metabolite discovery, with PAA exemplifying its unexplored biochemical capabilities.

Isolation and characterization of two new species, Hymenobacter mellowenesis sp. nov. and Hymenobacter aranciens sp. nov., from soil

Strains M29T and ASUV-10-1T, which are aerobic, non-flagellated, and Gram-stain-negative, were isolated from soil samples collected in Inje (37°57'49.1"N 128°19'53.7"E) and Cheonan City (36°48'47.1"N 127°05'22.4"E), South Korea. Phylogenetic analyses based on rRNA gene sequences revealed that strains M29T and ASUV-10-1T form a distinct branch within the family Hymenobacter (order Cytophagales, class Cytophagia). Strain M29T is most closely related to Hymenobacter rubidus DG7BT with a 16 S rRNA gene sequence similarity of 97.05%. Strain ASUV-10-1T shows closest genetic similarity to Hymenobacter frigidus B1789T (96.42%), Hymenobacter jeongseonensis BT683T (95.97%), and Hymenobacter terricola 3F2TT (95.65%). The optimal growth conditions for these strains are pH 7.0, no NaCl, and a temperature of 25 °C. The dominant cellular fatty acids identified in these strains are iso-C15:0, anteiso-C15:0, and Summed Feature 3 (C16:1ω 7c / C16:1ω 6c). Both strains predominantly contain MK-7 as the respiratory quinone. The major polar lipids in strains M29T and ASUV-10-1T are phosphatidylethanolamine, aminophospholipid, and aminolipid. Based on biochemical, chemotaxonomic, and phylogenetic data, it is evident that M29T and ASUV-10-1T represent new species within the genus Hymenobacter. The new species were classified based on biochemical and chemotaxonomic characteristics. The taxonomic classification of these species was conducted following the guidelines and protocols outlined in Bergey's Manual of Systematic Bacteriology. We followed the methods for determining physiological and biochemical characteristics, as well as chemotaxonomic markers such as fatty acid profiles, quinone types, and polar lipid compositions. We also compared with the results of carbohydrate utilization and enzyme activities results [Bergey 1994]. Therefore, we propose the names Hymenobacter mellowenesis for strain M29T (= KCTC 102056T = NBRC 116578T) and Hymenobacter aranciens for strain ASUV-10-1T (= KCTC 92969T = NBRC 116575T).

Active microbiota persist in dry permafrost and active layer from Elephant Head, Antarctica

Dry permafrost is a challenging environment for microbial life due to cold, dry, and often oligotrophic conditions. In 2016, Elephant Head, Antarctica, was confirmed as the second site on Earth to contain dry permafrost. It is geographically distinct from the McMurdo Dry Valleys where dry permafrost has been studied previously. Here, we present the first study of the microbial activity, diversity, and functional potential of Elephant Head dry permafrost. Microbial activity was measured using radiorespiration assays with radiolabeled acetate as a carbon source at 5, 0, and -5°C. Low, but detectable, rates of microbial activity were measured in some samples at 0 and -5°C. This is distinct from previous studies of McMurdo Dry Valley dry permafrost which concluded that dry permafrost represents a cold-arid limit to life on the planet. The isolation of cold-adapted organisms from these soils, including one capable of subzero growth, further supports that the Elephant Head dry active layer and dry permafrost harbor viable microbial life, which may be active in situ. Metagenomic, 16S rRNA gene, and internal transcribed spacer and amplicon sequencing identified similar microbial communities to other Antarctic and cold environments. The Elephant Head microbial community appears to be adapted for survival in cold, dry, and oligotrophic conditions based on the presence of cold adaptation and stress response genes in the metagenomes. Together, our results show that dry permafrost environments do not exclude active microbial life at subzero temperatures, suggesting that the cold, dry soils of Mars may also not be as inhospitable as previously thought.

Hymenobacter endophyticus sp. nov., isolated from wheat leaf tissue

A bacterium, designated strain ZK17L-C2T, was isolated from the leaf tissues of wheat (Triticum aestivum) collected in Chengdu, Sichuan Province, PR China. It is aerobic, non-motile, Gram-negative, rod-shaped and red-to-pink in colour. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZK17L-C2T belonged to the genus Hymenobacter and was most closely related to Hymenobacter rigui KCTC 12533T (98.68 %) and Hymenobacter metallilatus 9PBR-2T (98.19 %). Digital DNA-DNA hybridization (dDDH) values between strain ZK17L-C2T and these two type strains were 26.6 and 26.5 %, and average nucleotide identity (ANI) values were 84.9 and 84.8 %, respectively; these values are lower than the proposed and generally accepted species boundaries for dDDH and ANI. The genomic DNA G+C content of strain ZK17L-C2T was 59.4 mol%. It can grow at pH 5.5-7.5 and 15-30 °C, which is different from the closely related type strains. The major fatty acids of strain ZK17L-C2T were iso-C15 : 0, C16 : 0 and C18 : 0. Overall, the results from biochemical, chemical taxonomy and phylogenetic analyses indicate that strain ZK17L-C2T (=CGMCC 1.19373T=KCTC 92184 T) represents a new species of the genus Hymenobacter, for which the name Hymenobacter endophyticus sp. nov. is proposed.

Five novel Hymenobacter species isolated from air: Hymenobacter cellulosilyticus sp. nov., Hymenobacter cellulosivorans sp. nov., Hymenobacter aerilatus sp. nov., Hymenobacter sublimis sp. nov. and Hymenobacter volaticus sp. nov

Five Hymenobacter strains isolated from air samples collected from the Suwon and Jeju regions of the Republic of Korea were studied using polyphasic taxonomic methods. Using 16S rRNA gene sequences and the resulting phylogenetic tree, the strains were primarily identified as members of the genus Hymenobacter. Digital DNA-DNA hybridization values and average nucleotide identities values for species delineation (70 and 95-96 %, respectively) between the five strains and their nearest type strains indicated that each strain represented a novel species. All strains were aerobic, Gram-stain-negative, mesophilic, rod-shaped and catalase- and oxidase-positive, with red to pink coloured colonies. The genome sizes of the five strains varied from 4.8 to 7.1 Mb and their G+C contents were between 54.1 and 59.4 mol%. Based on their phenotypic, chemotaxonomic and genotypic characteristics, we propose to classify these isolates into five novel species within the genus Hymenobacter for which we propose the names, Hymenobacter cellulosilyticus sp. nov., Hymenobacter cellulosivorans sp. nov., Hymenobacter aerilatus sp. nov., Hymenobacter sublimis sp. nov. and Hymenobacter volaticus sp. nov., with strains 5116 S-3T (=KACC 21925T=JCM 35216T), 5116 S-27T (=KACC 21926T=JCM 35217T), 5413 J-13T (=KACC 21928T=JCM 35219T), 5516 S-25T (=KACC 21931T=JCM 35222T) and 5420 S-77T (=KACC 21932T=JCM 35223T) as the type strains, respectively.

Hymenobacter canadensis sp. nov., isolated from freshwater of the pond in Cambridge Bay, Canada

A Gram-stain-negative, aerobic, reddish-coloured, rod-shaped and non-motile strain PAMC 29467^T, was isolated from freshwater of the pond in Cambridge Bay, Canada. Strain PAMC 29467^T was closely related to Hymenobacter yonginensis (98.1 % 16S rRNA gene similarity). Genomic relatedness analyses showed that strain PAMC 29467^T is distinguishable from H. yonginensis based on average nucleotide identity (91.3 %) and digital DNA-DNA hybridization values (39.3 %). The major fatty acids (>10 %) of strain PAMC 29467^T were summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), C_15 : 0 iso, C_16 : 1  ω5c and summed feature 4 (C_17 : 1 iso l and/or anteiso B). The major respiratory quinone was menaquinone-7. The genomic DNA G+C content was 61.5 mol%. Strain PAMC 29467^T was separated from the type species in the genus Hymenobacter by its distinct phylogenetic position and some physiological characteristics. As a result, a novel species is proposed, with the name Hymenobacter canadensis sp. nov. (type strain, PAMC 29467^T=KCTC 92787^T=JCM 35843^T).

Description of Hymenobacter sediminicola sp. nov., isolated from contaminated sediment

A polyphasic taxonomic study was conducted on two Gram-negative, non-sporulating, non-motile bacterial strains, S2-20-2^T and S2-21-1, isolated from a contaminated freshwater sediment in China. Comparative 16S rRNA gene sequence studies revealed a clear affiliation of two strains with Bacteroidetes, which showed the highest pairwise sequence similarities with Hymenobacter duratus BT646^T (99.3%), Hymenobacter psychrotolerans Tibet-IIU11^T (99.3%), Hymenobacter kanuolensis T-3^T (97.6%), Hymenobacter swuensis DY53^T (96.9%), Hymenobacter tenuis POB6^T (96.8%), Hymenobacter seoulensis 16F7G^T (96.7%), and Hymenobacter rigui KCTC 12533^T (96.5%). The phylogenetic analysis based on 16S rRNA gene sequences showed that two strains formed a clear phylogenetic lineage with the genus Hymenobacter. Major fatty acids were identified as iso-C_15:0, anteiso-C_15:0, and summed feature 3 (C_16:1 ω6c and/or C_16:1 ω7c/t) and summed feature 4 (iso-C_17:1 I and/or anteiso-C_17:1 B). Major cellular polar lipids were identified as phosphatidylethanolamine, three unidentified aminolipids, an unidentified aminophosopholipid and an unidentified lipid. The respiratory quinone was detected as MK-7 and the genomic DNA G + C content was determined to be 57.9% (genome) for type strain S2-20-2^T and 57.7 mol% (HPLC) for strain S2-21-1. The observed ANI and dDDH values between strain S2-20-2^T and its closely related strains were 75.7-91.4% and 21.2-43.9%, respectively. Based on physiological, biochemical, genetic and genomic characteristics, we propose that strains S2-20-2^T and S2-21-1 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter sediminicola sp. nov. is proposed. The type strain is S2-20-2^T (= CGMCC 1.18734^T = JCM 35801^T).

Four new members of the family Cytophagaceae: Chryseosolibacter histidini gen. nov., sp. nov., Chryseosolibacter indicus gen. nov., sp. nov., Dawidia cretensis, gen. nov., sp. nov., and Dawidia soli, gen. nov., sp. nov. isolated from diverse habitat

Four novel strains were isolated: PWU4^T and PWU20^T were both from soil in Germany, PWU5^T was isolated from soil in India and PWU37^T was obtained from sheep faeces collected on the Island of Crete. Cells of each were observed to be Gram-negative, strictly aerobic, rod shaped, and to grow optimally between 28 and 34 °C, between pH 7.0 and 8.0 and without the addition of NaCl. The strains were found to be catalase and oxidase-negative and able to grow on most mono- and disaccharides, a few polysaccharides and organic acids. Their predominant menaquinone was identified as MK-7. Their major fatty acids were identified as C_16:1ω7c (PWU4^T and PWU20^T) and C_16:1ω5c (PWU5^T and PWU37^T). The DNA G + C contents of strains PWU4^T, PWU20^T, PWU5^T and PWU37^T were determined to be 50.2 mol%, 51.6 mol %, 39.8 mol% and 53.8 mol%, respectively. The 16S rRNA gene sequence analysis revealed that the close relatives Ohtaekwangia koreensis 3B-2^T and Ohtaekwangia kribbensis 10AO^T share less than 93.8% sequence similarity. The strains were classified in two groups, where PWU4^T and PWU20^T share 93.0% sequence similarity, and PWU5^T and PWU37^T share 97.5% sequence similarity. However, the members of each group were concluded to represent different species based on the low average nucleotide identity (ANI) of their genomes, 69.7% and 83.8%, respectively. We propose that the four strains represent four novel species of two new genera in the family Cytophagaceae. The type species of the novel genus Chryseosolibacter is Chryseosolibacter histidini gen. nov., sp. nov. with the type strain PWU4^T (= DSM 111594^T = NCCB 100798^T), whilst strain PWU20^T (= DSM 111597^T = NCCB 100800^T) is the type strain of a second species, Chryseosolibacter indicus sp. nov. The type species of the novel genus Dawidia is Dawidia cretensis gen. nov., sp. nov. with the type strain PWU5^T (= DSM 111596^T = NCCB 100799^T), whilst strain PWU37^T (= DSM 111595^T = NCCB 100801^T) is the type stain of a second species, Dawidia soli sp. nov.

Hymenobacter translucens sp. nov. and Hymenobacter pini sp. nov. isolated from soil

Two novel bacterial strains BT175^T and BT728^T were isolated from soil collected in the Republic of Korea. Both strains were Gram stain negative, rod shaped, and had circular, convex, and pink-colored colonies. The 16S rRNA gene sequence similarity between the strains BT175^T and BT728^T was 93.6%, indicating that they represent a distinct species. 16S rRNA sequence analysis indicated that strains BT175^T and BT728^T belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes). Strain BT175^T was closely related to Hymenobacter persicinus 1-3-3-3^T (97.2%, 16S rRNA gene similarity), Hymenobacter knuensis 16F7C-2^T (96.6%), and Hymenobacter daejeonensis PB105^T (96.1%). Strain BT728^T was closely related to Hymenobacter rigui KCTC 12533^T (98.4%), Hymenobacter metallilatus 9PBR-2^T (97.6%), and Hymenobacter perfusus LMG26000^T (97.4%). Strain BT175^T and BT728^T were found to have the MK-7 as the major respiratory quinone. The DNA G + C content of strain BT175^T was 61.6 mol% and BT728^T was 59.6 mol%, respectively. Characterization based on polyphasic analysis indicated that strains BT175^T and BT728^T represent novel species of the genus Hymenobacter and the names Hymenobacter translucens sp. nov. and Hymenobacter pini sp. nov. are proposed. The type strain of Hymenobacter translucens is BT175^T (= KCTC 72330^T = NBRC 115441^T) and Hymenobacter pini is BT728^T (= KACC 22629^T = NBRC 115444^T).

Hymenobacter cyanobacteriorum sp. nov., isolated from a freshwater reservoir during the cyanobacterial bloom period

A Gram-negative, red-colored, and rod-shaped bacterial strain, DH14^T, was isolated from a eutrophic reservoir. The 16S rRNA gene sequence analysis showed that strain DH14^T was most closely related to Hymenobacter terrigena (98.3% similarity) and Hymenobacter terrae (98.1%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain DH14^T and its related type strains were below 82.9% and 27.2%, respectively. Strain DH14^T contained iso-C_15:0 (32.6%), anteiso-C_15:0 (14.0%), and summed feature 3 (C_16:1 ω6c and/or C_16:1 ω7c) (25.8%) as major cellular fatty acids. The main polar lipids were phosphatidylethanolamine, two unidentified aminophospholipids, and one unidentified lipid. The respiratory quinone was menaquinone 7 (MK-7). The genomic DNA G + C content was 62.1%. These evidences support the classification of strain DH14^T as a novel species in the genus Hymenobacter, for which the name Hymenobacter cyanobacteriorum sp. nov. is proposed. The type strain is DH14^T (= KCTC 92040^T = LMG 32425^T).

Hymenobacter siberiensis sp. nov., isolated from a marine sediment of the East Siberian Sea and Hymenobacter psoromatis sp. nov., isolated from an Antarctic lichen

Gram-stain-negative, strictly aerobic, red-pink-coloured, rod-shaped and non-motile bacterial strains PAMC 29290, PAMC 29294T and PAMC 29296 were isolated from marine surface sediment sampled in the East Siberian Sea and strains PAMC 26553 and PAMC 26554T were obtained from an Antarctic lichen. Strains PAMC 29290, PAMC 29294T and PAMC 29296 were closely related to Hymenobacter artigasi (98.8 % 16S rRNA gene similarity), Hymenobacter antarcticus (97.3 %) and Hymenobacter glaciei (96.9 %), and PAMC 26553 and PAMC 26554T showed high similarity to Hymenobacter ginsengisoli (97.0 %), Hymenobacter rivuli (96.1 %) and Hymenobacter setariae (95.9 %). Genomic relatedness analyses showed that strains PAMC 29290, PAMC 29294T and PAMC 29296 could be distinguished from H. artigasi by average nucleotide identity (ANI; 93.1–93.2 %) and digital DNA–DNA hybridization (dDDH; 50.3–51.0 %) values. Strains PAMC 26553 and PAMC 26554T could be clearly distinguished from H. ginsengisoli with ANI values <79.8 % and dDDH values <23.3 %. The major fatty acids of strains PAMC 29290, PAMC 29294T and PAMC 29296 were C15 : 0 iso (21.0–26.0 %), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c; 17.4–18.2 %), C15 : 0 anteiso (12.7–19.1 %) and summed feature 4 (C17 : 1 iso I and/or anteiso B; 8.6–16.1 %) and those of strains PAMC 26553 and PAMC 26554T were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c; 20.7–22.2 %), C15 : 0 anteiso (17.5–19.7 %) and summed feature 4 (C17 : 1 iso I and/or anteiso B; 15.5–18.1 %). The major respiratory quinone was MK-7. The genomic DNA G+C contents were 60.6–60.8 mol%. The polar lipids of PAMC 29294T were found to consist of phosphatidylethanolamine, four unidentified aminolipids, an unidentified aminophospholipid and five unidentified lipids; those of PAMC 26554T were phosphatidylethanolamine, three unidentified aminolipids, four unidentified aminophospholipid and two unidentified lipids. The distinct phylogenetic position and some physiological characteristics distinguished the novel strains from closely related type strains in the genus Hymenobacter . Thus, two novel species are proposed, with the names Hymenobacter siberiensis sp. nov. (type strain, PAMC 29294T=KCTC 82466T=JCM 34574T) and Hymenobacter psoromatis sp. nov. (type strain, PAMC 26554T=KCTC 82464T=JCM 34572T), respectively.

Hymenobacter armeniacus sp. nov. and Hymenobacter montanus sp. nov., two radiation-resistant bacteria from soil

Two bacterial strains, designated BT189T and BT664T, were isolated from soil sampled in the Republic of Korea. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strains BT189T and BT664T belonged to the genus Hymenobacter , family Hymenobacteraceae (order Cytophagales ). The 16S rRNA genes of the two strains shared a sequence similarity of 93.7 %. The closely related species of strain BT189T were Hymenobacter rubidus DG7BT (97.1 % 16S rRNA similarity) and Hymenobacter terrae DG7AT (96.7 %). The closest related species to strain BT664T were Hymenobacter sedentarius DG5BT (95.3 %) and Hymenobacter terrenus MIMtkLc17T (95.2 %). The genome sizes of strains BT189T and BT664T were 5 285 287 and 5 475 357 bp, respectively. The genomic DNA G+C contents of strains BT189T and BT664T were 63.2 and 59.3 mol%, respectively. The main fatty acids of strain BT189T were iso-C15 : 0, anteiso-C15 : 0 and summed feature 3 (C16 : 1  ω6c/C16 : 1  ω7c), and those of strain BT664T were iso-C15 : 0, C16 : 1  ω5c and summed feature 3 (C16 : 1  ω6c/C16 : 1  ω7c). The main polar lipid in both strains was phosphatidylethanolamine and the predominant respiratory quinone was MK-7, supporting the affiliation of these strains with the genus Hymenobacter . Based on the results of biochemical, chemotaxonomic and phylogenetic analyses, two novel species, Hymenobacter armeniacus BT189T (=KCTC 72341T=NBRC 114843T) and Hymenobacter montanus BT664T (KACC 21967T=NBRC 114856T), are proposed.

Sabulibacter ruber gen. nov., sp. nov., a novel bacterium in the family Hymenobacteraceae, isolated from desert soil

A novel Gram-stain-negative, aerobic, oxidase-positive, catalase-positive, non-motile, short rod-shaped, red-pigmented strain, designated as SYSU D00434T, was isolated from a dry sandy soil sample collected from the Gurbantunggut desert in Xinjiang, north-west PR China. Strain SYSU D00434T was found to grow at 4–37 °C (optimum, 28–30 °C), pH 6.0–8.0 (optimum, pH 7.0) and with 0–1.5 % (w/v) NaCl (optimum, 0–0.5 %). The predominant respiratory quinone was MK-7 and the major fatty acids (>10 %) were C16 : 1  ω5c, iso-C15 : 0, summed feature 3 (C16 : 1  ω6c and/or C16 : 1  ω7c) and summed feature 4 (anteiso-C17 : 1 B and/or iso-C17 : 1 I). The polar lipids consisted of phosphatidylethanolamine, two unidentified polar lipids, two unidentified aminolipids, two unidentified phospholipids and two unidentified glycolipids. The genomic DNA G+C content of strain SYSU D00434T was 50.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain SYSU D00434T belonged to the family Hymenobacteraceae , and shared a sequence similarity of less than 94.6 % to all validly named taxa. Based on the phenotypic, phylogenetic and chemotaxonomic properties, strain D00434T is proposed to represent a new species of a new genus, named Sabulibacter ruber gen. nov., sp. nov., within the family Hymenobacteraceae . The type strain is SYSU D00434T (=CGMCC 1.18624T=KCTC 82276T=MCCC 1K04975T).

Hymenobacter terricola sp. nov., isolated from Antarctic soil

Strain 3F2T was isolated from a soil sample obtained from the surface of Deception Island, Antarctica. The isolate was a Gram-stain-negative, aerobic, non-motile, rod-shaped bacterium, and its colonies were red to pink in colour. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 3F2T belonged to the genus Hymenobacter , family Hymenobacteraceae and was most closely related to Hymenobacter sedentarius DG5BT (97.0% sequence similarity), Hymenobacter soli PB17T (96.9%), Hymenobacter terrae DG7AT (96.8%) and Hymenobacter rufus S1-2-2-6T (96.5%). Growth occurred at 4–20 °C (optimum, 10 °C), up to 1.0 % (w/v) NaCl (optimum, 0%) and pH 6.0–8.0 (optimum, pH 7.0). The chemotaxonomic characteristics of strain 3F2T, which had MK-7 as its predominant menaquinone and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), iso-C15:0, anteiso-C15:0 and C16:1 ω5c as its major fatty acids, were consistent with classification in the genus Hymenobacter . The polar lipid profile of strain 3F2T comprised phosphatidylethanolamine, two unidentified aminolipids, two unidentified aminophospholipids and three unidentified polar lipids. The genome of strain 3F2T was 6.56 Mbp with a G+C content of 61.5 mol%. Average nucleotide identity (ANI) values between 3F2T and the other species of the genus Hymenobacter were found to be low (ANIm <87.0%, ANIb <82.0% and OrthoANIu <83.0%). Furthermore, digital DNA–DNA hybridization and average amino acid identity values between strain 3F2T and the closely related species ranged from 20.0 to 26.3% and from 64.0 to 81.1 %, respectively. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain 3F2T represents a novel species within the genus Hymenobacter , for which the name Hymenobacter terricola sp. nov. is proposed. The type strain is 3F2T (=KCTC 72468T=CGMCC 1.13716T).

Hymenobacter piscis sp. nov., isolated from a fish pond

Bacterial strain NST-14T, isolated from a freshwater fish pond in Taiwan, was characterized using a polyphasic taxonomy approach. The strain was Gram-stain-negative, strictly aerobic, non-motile, rod-shaped and formed pink colonies. Optimal growth occurred at 30 °C, pH 7 and in the absence of NaCl. Phylogenetic analyses based on 16S rRNA gene sequences and coding sequences of 92 protein clusters indicated that strain NST-14T formed a phylogenetic lineage in the genus Hymenobacter . Analysis of 16S rRNA gene sequences showed that strain NST-14T had the highest similarity to Hymenobacter actinosclerus CCUG 39621T (97.7%), Hymenobacter amundsenii P5136T (97.3%) and Hymenobacter humicola P6312T (96.9%). Strain NST-14T showed 75.1–85.3 % average nucleotide identity, 73.7–89.8 % average amino acid identity and 14.5–26.0 % digital DNA–DNA hybridization with the type strains of other closely related Hymenobacter species. Strain NST-14T contained iso-C15 : 0, C16 : 1  ω5c and summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c) as the predominant fatty acids. The major hydroxyl fatty acids were iso-C17 : 0 3-OH and iso-C15 : 0 3-OH. The polar lipids were phosphatidylethanolamine, one unidentified glycolipid, four unidentified aminophospholipids, one unidentified aminolipid, two unidentified phospholipids and three unidentified lipids. The major polyamine was homospermidine. The major isoprenoid quinone was MK-7. The DNA G+C content of the genomic DNA was 62.4 mol%. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain NST-14T should be classified as a novel species of the genus Hymenobacter , for which the name Hymenobacter piscis sp. nov. is proposed. The type strain is NST-14T (=BCRC 81249T=LMG 31686T).

Functional filtering and random processes affect the assembly of microbial communities of snow algae blooms at Maritime Antarctic

The increasing temperatures at the West Antarctic Peninsula (Maritime Antarctic) could lead to a higher occurrence of snow algal blooms which are ubiquitous events that change the snow coloration, reducing albedo and in turn exacerbating melting. However, there is a limited understanding of snow algae blooms biodiversity, composition, and their functional profiles, especially in one of the world's areas most affected by climate change. In this study we used 16S rRNA and 18S rRNA metabarcoding, and shotgun metagenomics to assess the diversity, composition, and functional potential of the snow algae blooms bacterial and eukaryotic communities at three different sites of Maritime Antarctic, between different colors of the algae blooms and between seasonal and semi-permanent snowfields. We tested the hypothesis that the functional potential of snow algae blooms is conserved despite a changing taxonomic composition. Furthermore, we determined taxonomic co-occurrence patterns of bacteria and eukaryotes and assessed the potential for the exchange of metabolites among bacterial taxa. Here, we tested the prediction that there are co-occurring taxa within snow algae whose biotic interactions are marked by the exchange of metabolites. Our results show that the composition of snow algae blooms vary significantly among sites. For instance, a higher abundance of fungi and protists were detected in Fildes Peninsula compared with Doumer Island and O'Higgins. Likewise, the composition varied between snow colors and snow types. However, the functional potential varied only among sampling sites with a higher abundance of genes involved in tolerance to environmental stress at O'Higgins. Co-occurrence patterns of dominant bacterial genera such as Pedobacter, Polaromonas, Flavobacterium and Hymenobacter were recorded, contrasting the absence of co-occurring patterns displayed by Chlamydomonadales algae with other eukaryotes. Finally, genome-scale metabolic models revealed that bacteria within snow algae blooms likely compete for resources instead of forming cooperative communities.

Hymenobacter telluris sp. nov., isolated from soil in South Korea

Two novel bacterial strains, designated as BT186^T and BT505, were isolated from a soil sample collected in South Korea and characterized. Both strains were Gram-stain-negative, rod-shaped, aerobic, circular, convex, and had red-colored colonies. The level of 16S rRNA gene sequence similarity between the strains BT186^T and BT505 was 100%, indicating that they represent an identical species. 16S rRNA sequence analysis indicated that strains BT186^T and BT505 belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes, Kingdom Bacteria). Both strains were closely related to Hymenobacter norwichensis DSM 15439^T (98.3% 16S rRNA gene similarity), Hymenobacter aquaticus JCM 31653^T (96.8%), and Hymenobacter perfusus LMG26000^T (96.5%). Strain BT186^T was found to have the MK-7 as the major respiratory quinone. The major polar lipid of strain BT186^T was identified to be phosphatidylethanolamine (PE). The major cellular fatty acid profiles of strain BT186^T were C_16:1 ω5c (24.3%), iso-C_15:0 (20.3%) and summed feature 3 (C_16:1 ω6c/C_16:1 ω7c) (19.9%). Characterization based on polyphasic analysis indicated that strains BT186^T and BT505 represent novel species of the genus Hymenobacter and the name Hymenobacter telluris sp. nov. is proposed. The type strain of Hymenobacter telluris is BT186^T (= KCTC 72338^T = NBRC 114968^T).

Multiple energy sources and metabolic strategies sustain microbial diversity in Antarctic desert soils

Numerous diverse microorganisms reside in the cold desert soils of continental Antarctica, though we lack a holistic understanding of the metabolic processes that sustain them. Here, we profile the composition, capabilities, and activities of the microbial communities in 16 physicochemically diverse mountainous and glacial soils. We assembled 451 metagenome-assembled genomes from 18 microbial phyla and inferred through Bayesian divergence analysis that the dominant lineages present are likely native to Antarctica. In support of earlier findings, metagenomic analysis revealed that the most abundant and prevalent microorganisms are metabolically versatile aerobes that use atmospheric hydrogen to support aerobic respiration and sometimes carbon fixation. Surprisingly, however, hydrogen oxidation in this region was catalyzed primarily by a phylogenetically and structurally distinct enzyme, the group 1l [NiFe]-hydrogenase, encoded by nine bacterial phyla. Through gas chromatography, we provide evidence that both Antarctic soil communities and an axenic Bacteroidota isolate (Hymenobacter roseosalivarius) oxidize atmospheric hydrogen using this enzyme. Based on ex situ rates at environmentally representative temperatures, hydrogen oxidation is theoretically sufficient for soil communities to meet energy requirements and, through metabolic water production, sustain hydration. Diverse carbon monoxide oxidizers and abundant methanotrophs were also active in the soils. We also recovered genomes of microorganisms capable of oxidizing edaphic inorganic nitrogen, sulfur, and iron compounds and harvesting solar energy via microbial rhodopsins and conventional photosystems. Obligately symbiotic bacteria, including Patescibacteria, Chlamydiae, and predatory Bdellovibrionota, were also present. We conclude that microbial diversity in Antarctic soils reflects the coexistence of metabolically flexible mixotrophs with metabolically constrained specialists.

Hymenobacter puniceus sp. nov., radiation resistant bacteria isolated from soil in South Korea

Two novel Gram-negative bacterial strains BT190^T and BT191 were isolated from soil collected in Uijeongbu city (37°44'55″N, 127°02'20″E), Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains BT190^T and BT191 belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia). The level of 16S rRNA gene sequence similarity between the strains BT190^T and BT190 was 99.5%. The strains BT190^T and BT191 were closely related to Hymenobacter swuensis DY53^T (97.0% 16S rRNA gene similarity), Hymenobacter metallilatus 9PBR-2 ^T (96.8%), Hymenobacter tibetensis XTM003^T (96.8%) and Hymenobacter yonginensis HMD1010^T (96.6%). The genome size of strain BT190^T was 4,859,864 bp. The DNA G+C content of strain BT190^T was 55.3 mol%. Bacterial growth was observed at 4-30 °C (optimum 25 °C) and pH 6.0-9.0 (optimum, pH 6.0-7.0) on R2A agar. Colonies of strains BT190^T and BT191 were raised, smooth, circular and red-pink colored. The sole respiratory quinone of strain BT190^T was MK-7 and the predominant cellular fatty acids were iso-C_15:0, C_16:1 ω5c, summed feature 3 (C_16:1 ω6c / C_16:1 ω7c) and summed feature 4 (iso-C_17:1 I / anteiso-C_17:1 B). The major polar lipids of strain BT190^T were aminophospholipid (APL) and phosphatidylethanolamine (PE). Based on the chemotaxonomic, biochemical, and phylogenetic analysis, strains BT190^T and BT191 can be suggested as a novel bacterial species within the genus Hymenobacter, for which the name Hymenobacter puniceus sp. nov is proposed. The type strain of Hymenobacter puniceus is BT190^T (= KCTC 72342 ^T = NBRC 114860 ^T).

Hymenobacter taeanensis sp. nov., radiation resistant bacterium isolated from coastal sand dune

An aerobic, Gram-stain-negative, non-motile, non-spore-forming, rod-shaped, and light pink-colored bacterial strain, designated TS19^T, was isolated from a sand sample obtained from a coastal sand dune after exposure to 3 kGy of gamma radiation. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the isolate was a member of the genus Hymenobacter and was most closely related to H. wooponensis WM78^T (98.3% similarity). Strain TS19^T and H. wooponensis showed resistance to gamma radiation with D₁₀ values (i.e., the dose required to reduce the bacterial population by tenfold) of 7.3 kGy and 3.5 kGy, respectively. The genome of strain TS19^T consists of one contig with 4,879,662 bp and has a G + C content of 56.2%. The genome contains 3,955 protein coding sequences, 44 tRNAs, and 12 rRNAs. The predominant fatty acids of strain TS19^T were iso-C_15:0, summed feature 4 (iso-C_17:1 I and/or anteiso-C_17:1 B), summed feature 3 (C_16:1 ω6c and/or C_16:1 ω7c), and C_16:1 ω5c. The major polar lipids were phosphatidylethanolamine, and one unidentified aminophospholipid. The main respiratory quinone was menaquinone-7. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain TS19^T represents a novel species, for which the name Hymenobacter taeanensis sp. nov. is proposed. The type strain is TS19^T (= KCTC 72897^T = JCM 34023^T).

Hymenobacter caeli sp. nov., an airborne bacterium isolated from King George Island, Antarctica

A rod-shaped and Gram-stain-negative bacterial strain 9A^T, was isolated from an air sample collected at King George Island, maritime Antarctica. Phylogenetic analysis based on 16S rRNA gene sequence reveals that strain 9A^T belongs to the genus Hymenobacter and shows the highest similarity to Hymenobacter coccineus CCM 8649^T (96.8 %). The DNA G+C content based on the draft genome sequence is 64.9 mol%. Strain 9A^T is strictly aerobic, psychrophilic, catalase-positive, oxidase-positive and non-motile. Growth is observed at 0-20 °C (optimum 10 °C), pH 6.0-8.0 (optimum pH 7.0), and in the absence of NaCl. The predominant menaquinone of strain 9A^T is MK-7 and the major fatty acids comprise Summed Feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c; 25.2 %), iso-C_15 : 0 (23.2 %), C_16 : 1  ω5c (11.6 %), Summed Feature 4 (anteiso-C_17 : 1 B/iso-C_17 : 1 I) (9.6 %) and anteiso-C_15 : 0 (9.6 %). The polar lipid profile consists of the major lipid phosphatidylethanolamine and moderate to minor amounts of phosphatidylserine, unidentified aminolipids, aminophospholipids, aminophosphoglycolipids, polar lipids lacking a functional group and an unidentified phospholipid and a glycolipid. In the polyamine pattern sym-homospermidine is predominant. On the basis of the results obtained, strain 9A^T is proposed as a novel species of the genus Hymenobacter, for which the name Hymenobacter caeli sp. nov. is suggested. The type strain is 9A^T (=CCM 8971^T=LMG 32109^T=DSM 111653^T).

Hymenobacter negativus sp. nov., bacteria isolated from mountain soil collected in South Korea

Two novel Gram-negative bacterial strains BT442^T and BT584 were isolated from dry soil collected in mountains Busan and Guri, Korea during wintertime. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains BT442^T and BT584 both belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia). Strain BT442^T was closely related to Hymenobacter soli PB17^T (98.0% 16S rRNA gene similarity) and Hymenobacter terrae POA9^T (97.6%). No other recognized bacterial species showed more than 97% 16S rRNA gene sequence similarity to strains BT442^T. The genome size of strain BT442^T was 5,143,362 bp. Bacterial growth was observed at 10-30 °C (optimum 25 °C), pH 6.0-8.0 (optimum pH 6.0) in R2A agar and in the presence up to 1% NaCl. The major cellular fatty acids of strains BT442^T and BT584 were iso-C_15:0, anteiso-C_15:0 and summed feature 3 (C_16:1 ω6c / C_16:1 ω7c). In addition, their predominant respiratory quinone was MK-7. The major polar lipids of strains BT442^T and BT584 were identified to be phosphatidylethanolamine, aminophospholipid, and aminolipid. Based on the biochemical, chemotaxonomic, and phylogenetic analyses, strains BT442^T and BT584 are novel bacterial species within the genus Hymenobacter, and the proposed name is Hymenobacter negativus. The strain type of Hymenobacter negativus is BT442^T (= KCTC 72902^T = NBRC XXXX^T).

Hymenobacter citatus sp. nov., isolated from soil in South Korea

Two novel Gram-negative bacterial strains, BT507^T and BT506, were isolated from soil collected in Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that both strains BT507^T and BT506 belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae; order Cytophagales; class Cytophagia). The 16S rRNA genes of the two strains shared a sequence similarity of 100.0%. Strains BT507^T and BT506 are closely related to Hymenobacter profundi M2^T (97.2% 16S rRNA gene similarity), Hymenobacter defluvii POA9^T (97.1%), and Hymenobacter tenuis POB6^T (95.3%). The genome size of strain BT507^T is 5,078,289 base pairs. Bacterial growth was observed at 10-37 °C (optimum 25 °C) and pH 6.0-8.0 (optimum pH 6.0). The primary cellular fatty acids of strain BT507^T are iso-C_15:0, C_16:1ω5c, and summed feature 3 (C_16:1ω6c/C_16:1ω7c). Its predominant respiratory quinone is MK-7. The primary polar lipids of strain BT507^T are lipid, aminophospholipid, and phosphatidylethanolamine. Based on the biochemical, chemotaxonomic, and phylogenetic analysis, strains BT507^T and BT506 can be described a novel bacterial species within the genus Hymenobacter, and the proposed name is Hymenobacter citatus. The type strain of H. citatus is BT507^T is KCTC 82115^T and NBRC 114850^T.

Pigments from Antarctic bacteria and their biotechnological applications

Pigments from microorganisms have triggered great interest in the market, mostly by their "natural" appeal, their favorable production conditions, in addition to the potential new chemical structures or naturally overproducing strains. They have been used in: food, feed, dairy, textile, pharmaceutical, and cosmetic industries. The high rate of pigment production in microorganisms recovered from Antarctica in response to selective pressures such as: high UV radiation, low temperatures, and freezing and thawing cycles makes this a unique biome which means that much of its biological heritage cannot be found elsewhere on the planet. This vast arsenal of pigmented molecules has different functions in bacteria and may exhibit different biotechnological activities, such as: extracellular sunscreens, photoprotective function, antimicrobial activity, biodegradability, etc. However, many challenges for the commercial use of these compounds have yet to be overcome, such as: the low stability of natural pigments in cosmetic formulations, the change in color when subjected to pH variations, the low yield and the high costs in their production. This review surveys the different types of natural pigments found in Antarctic bacteria, classifying them according to their chemical structure. Finally, we give an overview of the main pigments that are used commercially today.

Hymenobacter terrestris sp. nov. and Hymenobacter lapidiphilus sp. nov., isolated from regoliths in Antarctica

A group of four psychrotrophic bacterial strains was isolated on James Ross Island (Antarctica) in 2013. All isolates, originating from different soil samples, were collected from the ice-free northern part of the island. They were rod-shaped, Gram-stain-negative, and produced moderately slimy red-pink pigmented colonies on R2A agar. A polyphasic taxonomic approach based on 16S rRNA gene sequencing, whole-genome sequencing, MALDI-TOF MS, rep-PCR analyses, chemotaxonomic methods and extensive biotyping was used to clarify the taxonomic position of these isolates. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates belonged to the genus Hymenobacter. The closest relative was Hymenobacter humicola CCM 8763^T, exhibiting 98.3 and 98.9% 16S rRNA pairwise similarity with the reference isolates P5342^T and P5252^T, respectively. Average nucleotide identity, digital DNA-DNA hybridization and core gene distances calculated from the whole-genome sequencing data confirmed that P5252^T and P5342^T represent two distinct Hymenobacter species. The menaquinone systems of both strains contained MK-7 as the major respiratory quinone. The predominant polar lipids for both strains were phosphatidylethanolamine and one unidentified glycolipid. The major components in the cellular fatty acid composition were summed feature 3 (C_16:1 ω7c/C_16:1ω6c), C_16:1ω5c, summed feature 4 (anteiso-C_17:1 B/iso-C_17:1 I), anteiso-C_15:0 and iso-C_{15 : 0} for all isolates. Based on the obtained results, two novel species are proposed, for which the names Hymenobacter terrestris sp. nov. (type strain P5252^T=CCM 8765^T=LMG 31495^T) and Hymenobacter lapidiphilus sp. nov. (type strain P5342^T=CCM 8764^T=LMG 30613^T) are suggested.

Spirosoma aureum sp. nov., and Hymenobacter russus sp. nov., radiation-resistant bacteria in Cytophagales order isolated from soil

A Gram-stain-negative, aerobic, nonmotile, yellow-colored strain BT328^T and Gram-stain-negative, aerobic, non-motile, red-colored strain BT18^T were isolated from the soil collected in Korea. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain BT328^T formed a distinct lineage within the family Spirosomaceae (order Cytophagales, class Cytophagia) and was most closely related to a member of the genus Spirosoma, Spirosoma terrae 15J9-4^T (95.9% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C, pH 7.0 and in the absence of NaCl. The predominant cellular fatty acids were summed feature 3 (C_16:1 ω6c/C_16:1 ω7c) and C_16:1 ω5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain BT18^T formed a distinct lineage within the family Hymenobacteraceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes) and was most closely related to members of the genus Hymenobacter, Hymenobacter knuensis 16F7C-2^T (97.0% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C and pH 7.0 without NaCl. The major fatty acids were iso-C_15:0 and anteiso-C_15:0. The major menaquinone was MK-7. The major polar lipid was phosphatidylethanolamine. Biochemical, chemotaxonomic and phylogenetic analyses indicated that strains BT328^T and BT18^T represents a novel bacterial species within the genus Spirosoma and Hymenobacter, respectively. For which the name Spirosoma aureum and Hymenobacter russus is proposed. The type strain of S. aureum is BT328^T (=KCTC 72365^T = NBRC 114506^T) and the type strain of H. russus is BT18^T (=KCTC 62610^T = NBRC 114380^T).

Hymenobacter busanensis sp. nov., radiation-resistant species isolated from soil in South Korea

Two bacterial strains designated as MA3^T and BT182 were isolated from a soil sample in South Korea. Cells of the two strains were Gram-stain-negative, non-motile, rod-shaped and formed red colonies on R2A agar at 25 °C. The 16S rRNA genes of the two strains shared a sequence similarity of 99.8%. Both strains shared the highest 16S rRNA gene similarity of 96.8% with Hymenobacter edaphi NL^T, followed by Hymenobacter paludis KBP-30^T (96.3%), Hymenobacter coalescens WW84^T (96.3%) and Hymenobacter gummosus ANT-18^T (96.3%). Growth was observed at 15-37 °C (optimum 30 °C), pH 6-8 (optimum pH 7) and in the presence up to 1% NaCl. The genome size of strains MA3^T and BT182 is 4.9 Mb and 4.8 Mb, respectively. The genomic G + C content of both strains is 62.0 mol%. The main polar lipid of the strains was phosphatidylethanolamine, the only respiratory quinone detected was menaquinone-7 and the major fatty acids were anteiso-C_15:0, iso-C_15:0, summed feature 4 (iso-C_17:1 I/anteiso-C_17:1 B) and summed feature 3 (C_16:1 ω6c/C_16:1 ω7c), supporting the affiliation of these strains with the genus Hymenobacter. Based on the phylogenetic, genotypic, phenotypic and chemotaxonomic data, strains MA3^T and BT182 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter busanensis is proposed. The type strain is MA3^T (= KCTC 72631^T = NBRC 114193^T).

Hymenobacter baengnokdamensis sp. nov., Isolated from the Soil of a Crater Lake in Korea

An aerobic, Gram-stain-negative, non-motile, non-spore-forming, rod-shaped and pink-colored bacterial strain, designated BRD72^T, was isolated from a crater lake (Baengnokdam) at the top of Mt. Hallasan in the Republic of Korea. Cells were catalase-positive and oxidase-negative. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the isolate was a member of the genus Hymenobacter and most closely related to Hymenobacter marinus KJ035^T (96.2% similarity). The isolate was found to produce carotenoid pigment, but not flexirubin-type pigment. The predominant fatty acids of strain BRD72^T were summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c, 21.6%), iso-C_15:0 (17.9%), anteiso-C_15:0 (13.3%) and summed feature 4 (iso-C_17:1 I and/or anteiso-C_17:1 B, 11.3%). The major polar lipids were phosphatidylethanolamine, an unidentified amino lipid, and two unidentified aminophospholipids. The main respiratory quinone was menaquinone-7 (MK-7), and the main polyamine was homospermidine. The DNA G+C content was 59.8 mol%. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain BRD72^T represents a novel species, for which the name Hymenobacter baengnokdamensis sp. nov. is proposed. The type strain is BRD72^T (= KCTC 72649^T = JCM 33837^T).

Hymenobacter radiodurans sp. nov., isolated from soil in the Republic of Korea

A bacterial strain, designated 17J36-26^T, was isolated from the UV-irradiated soil from Jeju Island, South Korea. Cells are Gram negative, strictly aerobic, non-motile, non-spore forming, rod shaped, and catalase and oxidase positive. The major fatty acids of strain 17J36-26^T were summed feature 4 (17:1 iso I/17:1 anteiso B), summed feature 3 (16:1 ω6c/16:1 ω7c), C_16:1 ω5c and iso-C_15:0. The polar lipid profile contained phosphatidylethanolamine, unidentified aminophospholipid, phospholipids and four unidentified lipids. The G+C content of the strain 17J36-26^T was 62.6 mol%. The 16S rRNA gene sequence analysis showed that strain 17J36-26^T was phylogenetically related to Hymenobacter qilianensis DK6-37^T and Hymenobacter roseosalivarius AA718^T (97.5% and 96.8% sequence similarity, respectively). Strain 17J36-26^T showed resistance to UV radiation. Both average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strains 17J36-26^T and type strains of Hymenobacter species were lower than the cut-off (≥ 95-96% for ANI and ≥ 70% for isDDH) to define a bacterial new species. The polyphasic approach using genotypic, phenotypic and chemotaxonomic data showed that strain 17J36-26^T could be distinguished from its phylogenetically related species, and thus, the strain representative of a novel species within the genus Hymenobacter, for which the name Hymenobacter radiodurans sp. nov. (type strain 17J36-26^T = KCTC 62269^T = JCM 33185^T) is proposed.

Hymenobacter fodinae sp. nov. and Hymenobacter metallicola sp. nov., isolated from abandoned lead–zinc mine

Two novel strains, designated 92R-1T and 9PBR-1T, were isolated from abandoned lead–zinc ore collected in Meizhou, Guangdong Province, PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that they fell into the genus of Hymenobacte r and formed two distinct lineages. Strain 92R-1T was most closely related to Hymenobacter wooponensis JCM 19491T (98.7 %) and Hymenobacter gelipurpurascens LMG 21873T (98.5 %), while strain 9PBR-1T was most closely related to Hymenobacter chitinivorans LMG 21951T (99.0 %), Hymenobacter elongatus JCM 17223T (98.7 %) and Hymenobacter aquaticus JCM 31653T (98.1 %). Strain 92R-1Tshared average nucleotide identity values of 80.0–83.7 % and digital DNA–DNA hybridization values of 23.1–27.1 % with its closely related type strains, respectively, while strain 9PBR-1T shared corresponding values of 80.3–83.2 % and 23.6–26.7 % with its closely related type strains, respectively. The two novel strains could be clearly distinguished from their closely related type strains by enzyme activities and substrates assimilation, respectively. Both of them took iso-C15:0, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B) and C16:1 ω5c as major fatty acids, and showed clear differences from their closely relatives in the contents of several components. They contained menaquinone 7 as the major respiratory quinone and phosphatidylethanolamine as the dominant polar lipid. The G+C contents of strains 92R-1T and 9PBR-1T were 56.7 and 59.5 mol%, respectively. The results clearly supported that strains 92R-1T and 9PBR-1T represent two distinct novel species within the genus Hymenobacter , for which the names Hymenobacter fodinae sp. nov. (type strain 92R-1T=GDMCC 1.1493T=JCM 32697T) and Hymenobacter metallicola sp. nov. (type strain 9PBR-1T=GDMCC 1.1491T=JCM 32698T) are proposed.

Hymenobacter artigasi sp. nov., isolated from air sampling in maritime Antarctica

A rod-shaped and Gram-stain-negative bacterial strain, 1B^T, was isolated from an air sample collected at King George Island, maritime Antarctica. Strain 1B^T is strictly aerobic, psychrophilic, catalase-positive, oxidase-positive and non-motile. Growth of strain 1B^T is observed at 0-20 °C (optimum, 10 °C), pH 6.0-8.0 (optimum, pH 8.0) and in the presence of 0-1.0% NaCl (optimum, 0.5 % NaCl). Phylogenetic analysis based on 16S rRNA gene sequences places strain 1B^T within the genus Hymenobacter and shows the highest similarity to Hymenobacter antarcticus VUG-A42aa^T (97.5 %). The predominant menaquinone of strain 1B^T is MK-7 and the major fatty acids (>10 %) comprise summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c; 32.5 %), iso-C_15 : 0 (17.6 %) and anteiso C_15 : 0 (12.3 %). The polar lipid profile consists of the major compounds phosphatidylethanolamine, phosphatidylserine, two unidentified aminolipids and one unidentified phospholipid. The DNA G+C content based on the draft genome sequence is 61.2 mol%. Based on the data from the current polyphasic study, 1B^T represents a novel species of the genus Hymenobacter, for which the name Hymenobacter artigasi sp. nov. is suggested. The type strain is 1B^T (=CCM 8970^T=CGMCC 1.16843^T).

Hymenobacter polaris sp. nov., a psychrotolerant bacterium isolated from an Arctic station

A pink-pigmented, non-motile, Gram-stain-negative, rod-shaped bacterium, designated RP-2-7^T, was obtained from soil sampled at the Arctic station, Spitsbergen, Svalbard, Norway. Cells were strictly aerobic, psychrotolerant, grew optimally at 15-20 °C and hydrolysed CM-cellulose. Phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain RP-2-7^T formed a lineage within the family Hymenobacteraceae and clustered with members of the genus Hymenobacter. Its closest relative was Hymenobacter marinus KJ035^T (97.6 % sequence similarity). The sequence similarities to other strains were ≤96.9 %. The principal respiratory quinone was MK-7 and the major polar lipids were phosphatidylethanolamine and an unidentified aminophospholipid. The predominant cellular fatty acids were summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), anteiso-C_15 : 0, iso-C_15 : 0, C_16 : 1  ω5c and summed featured 4 (iso-C_17 : 1 I and/or anteiso-C_17 : 1 B). The DNA G+C content was 62.8 mol%. In addition, the average nucleotide identity and in silico DNA-DNA hybridization relatedness values between strain RP-2-7^T and closely related strains were lower than species demarcation thresholds. Based on the resuls of genomic, chemotaxonomic, phenotypic and phylogenetic analyses, strain RP-2-7^T represents novel species in the genus Hymenobacter, for which the name Hymenobacter polaris sp. nov. is proposed. The type strain is RP-2-7^T (=KACC 21670^T=NBRC 114391^T).

Hymenobacter ginkgonis sp. nov., isolated from bark of Ginkgo biloba

Strain HMF4947^T, isolated from the bark of a ginkgo tree, was a pale-pink coloured, Gram-stain-negative, non-motile, strictly aerobic and rod-shaped bacterium. The isolate grew optimally on Reasoner's 2A agar at 30 °C, pH 7.0 and with 0 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain HMF4947^T belonged to the genus Hymenobacter and was most closely related to Hymenobacter metalli A2-91^T (96.9 % sequence similarity) and Hymenobacter pomorum 9-2-1-1^T (96.5 %). The average nucleotide identity and estimated DNA-DNA hybridization values between strain HMF4947^T and Hymenobacter arizonensis DSM 17870^T were 74.3 and 20.5 %, respectively. The major fatty acids were summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), iso-C_15 : 0 and C_16 : 1  ω5c. The predominant isoprenoid quinone was menaquinone-7. The polar lipids comprised phosphatidylethanolamine, one unidentified aminoglycolipid, three unidentified aminophospholipids, one unidentified phospholipid, three unidentified aminolipids, two unidentified glycolipids and three unidentified polar lipids. The genomic DNA G+C content was 59.3 mol%. Thus, based on phylogenetic, phenotypic and chemotaxonomic data, strain HMF4947^T represents a novel species of the genus Hymenobacter, for which the name Hymenobacter ginkgonis sp. nov. is proposed. The type strain of the species is strain HMF4947^T (=KCTC 72780^T=NBRC 114271^T).

Comparative Genomic Study of Polar Lichen-Associated Hymenobacter sp. PAMC 26554 and Hymenobacter sp. PAMC 26628 Reveals the Presence of Polysaccharide-Degrading Ability Based on Habitat

The genus Hymenobacter is classified in the family Hymenobacteraceae under the phylum Bacteroidetes. They have been isolated from diverse environments, such as air, soil, and lichen, along with extreme polar environments, including the Arctic and Antarctic regions. The polar regions have attracted intense research interest for the discovery of novel microorganisms and their functions. Analysis of the polysaccharide utilization-related carbohydrate-active enzyme among the two lichen-associated polar organisms Hymenobacter sp. PAMC 26554 and Hymenobacter sp. PAMC 26628 was performed, along with its comparison with the complete genome of the same genus available in the NCBI database. The study was conducted relying on the AZCL screening data for the two polar lichen-associated species. While comparing with eight other complete genomes, differences in polysaccharide preferences based on the isolation environment and biosample source were discovered. All the species showed almost similar percentage of cellulose synthesis and degradation genes. However, the polar lichen-associated microorganism was found to have a high percentage of hemicellulose degradation genes, and less starch and laminarin degradation. The Hymenobacter species with higher number of hemicellulose degradation genes was found to have a lower number of starch and laminarin degradation genes and vice versa, highlighting the differences in polysaccharide utilization among the species.

Validating biochemical features at the genome level in the Antarctic bacterium Hymenobacter sp. strain UV11

We present experimental data that complement and validate some biochemical features at the genome level in the UVC-resistant Antarctic bacterium Hymenobacter sp. UV11 strain. The genome was sequenced, assembled and annotated. It has 6 096 246 bp, a GC content of 60.6% and 5155 predicted genes. The secretome analysis, by combining in silico predictions with shotgun proteomics data, showed that UV11 strain produces extracellular proteases and carbohydrases with potential biotechnological uses. We observed the formation of outer membrane vesicles, mesosomes and carbon-storage compounds by using transmission electron microscopy. The in silico analysis of the genome revealed the presence of genes involved in the metabolism of glycogen-like molecules and starch. By HPLC-UV-Vis analysis and 1H-NMR spectra, we verified that strain UV11 produces xanthophyll-like carotenoids such as 2'-hydroxyflexixanthin, and the in silico analysis showed that this bacterium has genes involved in the biosynthesis of cathaxanthin, zeaxanthin and astaxanthin. We also found genes involved in the repair of UV-damaged DNA such as a photolyase, the nucleotide excision repair system and the production of ATP-dependent proteases that are important cellular components involved in the endurance to physiological stresses. This information will help us to better understand the ecological role played by Hymenobacter strains in the extreme Antarctic environment.

Bacterial Diversity of a High-Altitude Permafrost Thaw Pond Located on Ojos del Salado (Dry Andes, Altiplano-Atacama Region)

Microbial ecology of permafrost, due to its ecological and astrobiological importance, has been in the focus of studies in past decades. Although permafrost is an ancient and stable environment, it is also subjected to current climate changes. Permafrost degradation often results in generation of thaw ponds, a phenomenon not only reported mainly from polar regions but also present in high-altitude permafrost environments. Our knowledge about microbial communities of thaw ponds in these unique, remote mountain habitats is sparse. This study presents the first culture collection and results of the next-generation DNA sequencing (NGS) analysis of bacterial communities inhabiting a high-altitude permafrost thaw pond. In February 2016, a permafrost thaw pond on the Ojos del Salado at 5900 m a.s.l. (meters above sea level) was sampled as part of the Hungarian Dry Andes Research Programme. A culture collection of 125 isolates was established, containing altogether 11 genera belonging to phyla Bacteroidetes, Actinobacteria, and Proteobacteria. Simplified bacterial communities with a high proportion of candidate and hitherto uncultured bacteria were revealed by Illumina MiSeq NGS. Water of the thaw pond was dominated by Bacteroidetes and Proteobacteria, while in the sediment of the lake and permafrost, members of Acidobacteria, Actinobacteria, Bacteroidetes, Patescibacteria, Proteobacteria, and Verrucomicrobia were abundant. This permafrost habitat can be interesting as a potential Mars analog.

Hymenobacter setariae sp. nov., isolated from the ubiquitous weedy grass Setaria viridis

A Gram-stain-negative, short-rod, aerobic, non-motile, red to pink-pigmented bacterium, designated Fur1T, was isolated from the dry spikelet clusters of a plant called Setaria viridis near Dongguk University. Phylogenetic analysis conducted based on 16S rRNA gene sequences indicated that strain Fur1T belonged to the genus Hymenobacter of the family Hymenobacteraceae . The 16S rRNA gene of Fur1T showed highest sequence similarity to those of Hymenobacter metalli KACC 17381T (97.5 %) and Hymenobacter marinus KACC 19042T (97.1 %). Growth occurred at 4–37 °C (optimum, 25–28 °C), up to 1.0 % NaCl (optimum, 0 %) and pH 5.5–9.0 (optimum, pH 6.0–7.5). The major fatty acids of strain Fur1T were identified as iso-C15 : 0, C16 : 1  ω5c, anteiso-C15 : 0, summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c) and summed feature 4 (comprising anteiso-C17 : 1B and/or iso-C17 : 1I) as the major cellular fatty acids. The predominant respiratory quinone was identified as MK-7. The polar lipids were phosphatidylethanolamine, five unidentified aminophospholipids, two unidentified phospholipids, one unidentified glycolipid and one unidentified polar lipid. The genomic DNA G+C content based on the draft genome sequence was 58.7 mol%. DNA–DNA relatedness between strain Fur1T and its closest relative was below 70 %. Characterization based on phylogenetic, chemotaxonomic and phenotypic analyses clearly indicated that strain Fur1T represents a novel species of the genus Hymenobacter , for which the name Hymenobacter setariae sp. nov. is proposed. The type strain is Fur1T (=KACC 19903T=NBRC=113691T).

Hymenobacter lutimineralis sp. nov., belonging to the family Hymenobacteraceae, isolated from zeolite

A red-pigmented bacterial strain, designated KIGAM108^T, within the family Hymenobacteraceae was isolated from zeolite in the Gampo-41 mine of the Gyeongju, Republic of Korea. This strain was a Gram-negative, strictly aerobic, non-spore forming, rod-shaped bacterium. Phylogenetic analysis of the 16S rRNA gene sequence of strain KIGAM108^T found that it was related to the genus Hymenobacter, with similarities of 96.6, 96.4, 95.5, and 95.0% to H. fastidiosus VUG-A124^T, H. algoricola VUG-A23a^T, H. crusticola MIMBbqt21^T, and H. daecheongensis DSM 21074^T, respectively. Strain KIGAM108^T grew in the presence of 0-0.5% (w/v) NaCl at 4-37 °C and pH 6.0-10.0. This isolate contained MK-7 as a respiratory quinone. The polar lipids of strain KIGAM108^T were identified as phosphatidylethanolamine, two unidentified aminophospholipids, one unidentified phospholipid and five unidentified lipids. The major fatty acids profile showed summed feature 3 (C_16:1ω6c and/or C_16:1ω7c) (22.3%), anteiso-C_15:0 (17.1%), C_16:1ω5c (13.3%), and iso-C_15:0 (11.0%). The genomic DNA G + C content was 60.0 mol%. Based on the polyphasic taxonomic data, strain KIGAM108^T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter lutimineralis sp. nov. is proposed. The type strain is KIGAM108^T (=KCTC 72263^T =JCM 33444^T).

Hymenobacter sediminis sp. nov., isolated from lake sediment

A Gram-stain-negative, facultatively aerobic, rod-shaped, motile by gliding and pink-pigmented bacterial strain, designated ELS1360^T, was isolated from a lake sediment sample collected in Inner Mongolia, PR China. Strain ELS1360^T grew optimally at 33 °C, at pH 6.5-7.0 and without NaCl. Strain ELS1360^T exhibited 97.3, 97.1 and 96.9 % 16S rRNA gene sequence similarities to Hymenobacter aquatilis HMF3095^T, Hymenobacter luteus JCM 30328^T and Hymenobacter latericoloratus JCM 30327^T, respectively, and 90.4-96.9 % to other members of the genus Hymenobacter. Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain ELS1360^T belonged to the genus Hymenobacter and clustered with H. luteus JCM 30328^T and H. latericoloratus JCM 30327^T. The predominant cellular fatty acids were iso-C_15:0, summed feature 3 and C_16:1ω5c. Strain ELS1360^T contained MK-7 as the sole menaquinone. The major polar lipids contained phosphatidylethanolamine and two unidentified lipids. The genomic DNA G+C content of strain ELS1360^T was 57.1 mol%. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain ELS1360^T represents a novel species within the genus Hymenobacter, for which the name Hymenobacter sediminis sp. nov. is proposed. The type strain is ELS1360^T (=KCTC 62449^T=MCCC 1H00319^T).

Characterization of black patina from the Tiber River embankments using Next-Generation Sequencing

Black patinas are very common biological deterioration phenomena on lapideous artworks in outdoor environments. These substrates, exposed to sunlight, and atmospheric and environmental agents (i.e. wind and temperature changes), represent extreme environments that can only be colonized by highly versatile and adaptable microorganisms. Black patinas comprise a wide variety of microorganisms, but the morphological plasticity of most of these microorganisms hinders their identification by optical microscopy. This study used Next-Generation Sequencing (NGS) (including shotgun and amplicon sequencing) to characterize the black patina of the travertine embankments (muraglioni) of the Tiber River in Rome (Italy). Overall, the sequencing highlighted the rich diversity of bacterial and fungal communities and allowed the identification of more than one hundred taxa. NGS confirmed the relevance of coccoid and filamentous cyanobacteria observed by optical microscopy and revealed an informative landscape of the fungal community underlining the presence of microcolonial fungi and phylloplane yeasts. For the first time high-throughput sequencing allowed the exploration of the expansive diversity of bacteria in black patina, which has so far been overlooked in routine analyses. Furthermore, the identification of euendolithic microorganisms and weathering agents underlines the biodegradative role of black patina, which has often been underestimated. Therefore, the use of NGS to characterize black patinas could be useful in choosing appropriate conservation treatments and in the monitoring of stone colonization after the restoration interventions.

Hymenobacter jejuensis sp. nov., a UV radiation-tolerant bacterium isolated from Jeju Island

A novel Gram-stain negative, aerobic, rod-shaped, non-motile and pink-coloured bacterium, designated strain 17J68-5^T, was isolated from soil in Jeju Island, Korea. The strain was found to grow at 18-37 °C (optimum 25 °C) in R2A medium at pH (6.0 to 7.5; optimum 6.5) in the presence of 0% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 17J68-5^T forms a distinct lineage within the family Hymenobacteraceae and is closely related to Hymenobacter daecheongensis DSM 21074^T (94.9% 16S rRNA gene sequence similarity), Hymenobacter rutilus K2-33028^T (94.6%) and Hymenobacter tibetensis XTM003^T (94.3%). The draft genome sequence of strain 17J68-5^Tis 5.1 Mb size. The calculated average nucleotide identity and the digital DNA-DNA hybridization between strain 17J68-5^T and closely related type strains were 81.3 to 84.1  % and 25.5 to 28.1%. The major cellular fatty acids (≥ 10%) of the strain 17J68-5^T were identified as summed feature 3 (C_16:1ω6c/C_16:1ω7c; 21.2%), iso-C_15:0 (19.1%), summed feature 4 (C_17:1 iso I/C_17:1 anteiso B; 17.9%) and C_16:1ω5c (13.1%). The predominant respiratory quinones were found to be menaquinone 7 and 6 (MK-7 and MK-6). The major polar lipid was found to be phosphatidylethanolamine. The genomic DNA G + C content based on the whole genome sequence is 59.6 mol %. The phenotypic, chemotaxonomic and genotypic properties clearly indicated that isolate 17J68-5^T represents a novel species within the genus Hymenobacter, for which the name Hymenobacter jejuensis sp. nov. is proposed. The type strain of Hymenobacter jejuensis is 17J68-5^T (= KCTC 62224^T = JCM 33182^T).

Biological Ice-Nucleating Particles Deposited Year-Round in Subtropical Precipitation

Airborne bacteria that nucleate ice at relatively warm temperatures (>-10°C) can interact with cloud water droplets, affecting the formation of ice in clouds and the residency time of the cells in the atmosphere. We sampled 65 precipitation events in southeastern Louisiana over 2 years to examine the effect of season, meteorological conditions, storm type, and ecoregion source on the concentration and type of ice-nucleating particles (INPs) deposited. INPs sensitive to heat treatment were inferred to be biological in origin, and the highest concentrations of biological INPs (∼16,000 INPs liter^-1 active at ≥-10°C) were observed in snow and sleet samples from wintertime nimbostratus clouds with cloud top temperatures as warm as -7°C. Statistical analysis revealed three temperature classes of biological INPs (INPs active from -5 to -10°C, -11 to -12°C, and -13 to -14°C) and one temperature class of INPs that were sensitive to lysozyme (i.e., bacterial INPs, active from -5 to -10°C). Significant correlations between the INP data and abundances of taxa in the Bacteroidetes, Firmicutes, and unclassified bacterial divisions implied that certain members of these phyla may possess the ice nucleation phenotype. The interrelation between the INP classes and fluorescent dissolved organic matter, major ion concentrations (Na⁺, Cl^-, SO₄ ^2-, and NO₃ ^-), and backward air mass trajectories indicated that the highest concentrations of INPs were sourced from high-latitude North American and Asian continental environments, whereas the lowest values were observed when air was sourced from marine ecoregions. The intra- and extracontinental regions identified as sources of biological INPs in precipitation deposited in the southeastern United States suggests that these bioaerosols can disperse and affect meteorological conditions thousands of kilometers from their terrestrial points of origin.IMPORTANCE The particles most effective at inducing the freezing of water in the atmosphere are microbiological in origin; however, information on the species harboring this phenotype, their environmental distribution, and ecological sources are very limited. Analysis of precipitation collected over 2 years in Louisiana showed that INPs active at the warmest temperatures were sourced from terrestrial ecosystems and displayed behaviors that implicated specific bacterial taxa as the source of the ice nucleation activity. The abundance of biological INPs was highest in precipitation from winter storms and implied that their in-cloud concentrations were sufficient to affect the formation of ice and precipitation in nimbostratus clouds.

Hymenobacter humicola sp. nov., isolated from soils in Antarctica

A set of three psychrotrophic bacterial strains was isolated from different soil samples collected at the deglaciated northern part of James Ross Island (Antarctica) in 2014. All isolates were rod-shaped, Gram-stain-negative, non-motile, catalase-positive and oxidase-negative, and produced moderately slimy red-pink pigmented colonies on Reasoner's 2A (R2A) agar. A polyphasic taxonomic approach based on 16S rRNA gene sequencing, whole-genome sequencing, automated ribotyping, MALDI-TOF MS, chemotaxonomy methods and extensive biotyping using conventional tests and commercial identification kits was applied to the isolates in order to clarify their taxonomic position. Phylogenetic analysis based on the 16S rRNA gene showed that all isolates belonged to the genus Hymenobacter with the closest relative being Hymenobacter aerophilus DSM 13606^T, exhibiting 98.5 % 16S rRNA gene pairwise similarity to the reference isolate P6312^T. Average nucleotide identity values calculated from the whole-genome sequencing data proved that P6312^T represents a distinct Hymenobacter species. The major components of the cellular fatty acid composition were summed feature 3 (C_16 : 1 ω7c/C_16 : 1 ω6c), C_16 : 1 ω5c, summed feature 4 (C_17 : 1 anteiso B/iso I), C_15 : 0 anteiso and C_15 : 0 iso. The menaquinone system of strain P6312^T contained MK-7 as the major respiratory quinone. The predominant polar lipids were phosphatidylethanolamine and an unidentified phospholipid. Moderate to minor amounts of three unidentified polar lipids, four unidentified aminophospholipids, one unidentified glycolipid and one unidentified phospholipid were also present. Based on the obtained results, we propose a novel species for which the name Hymenobacterhumicola sp. nov. is suggested, with the type strain P6312^T (=CCM 8763^T=LMG 30612^T).

Hymenobacter edaphi sp. nov., isolated from abandoned arsenic-contaminated farmland soil

A Gram-stain-negative, aerobic, rod-shaped, non-motile, pink-pigmented bacterium, designated NL^T, was isolated from arsenic-contaminated farmland soil. Strain NL^T showed the highest 16S rRNA gene sequence similarities with those of Hymenobacter jeollabukensis 1-3-3-8^T (98.9 %), Hymenobacter gummosus ANT-18^T (97.5 %), Hymenobacter paludis KBP-30^T (97.4 %), Hymenobacter ocellatus Myx2105^T (97.1 %) and Hymenobacter coalescens WW84^T (96.4 %). The values of genomic orthoANI and dDDH between strain NL^T and Hymenobacter jeollabukensis KCTC 52741^T was 90.5 and 41.2 %, respectively, and those between strain NL^T and Hymenobacter gummosus KCTC 52166^T was 84.4 and 28.4 %, respectively. Strain NL^T exhibited DNA-DNA hybridisation values of 41.3 and 44.1 % with Hymenobacter paludis KCTC 32237^T and Hymenobacter ocellatus DSM 11117^T, respectively. Strain NL^T had major fatty acids (>10 %) of summed feature 4 (iso-C_17 : 1 I and/or anteiso-C_17 : 1 B), iso-C_15 : 0 and anteiso-C_15 : 0 and the predominant polyamine of homospermidine. The only respiratory quinone was menaquinone-7. The polar lipids were phosphatidylethanolamine, phospholipid, three unidentified lipids and two amino lipids. Strain NL^T had a genome size of 6.04 Mb and the average G+C content of 65.6 %. Compared to the other Hymenobacter spp., strain NL^T is different in polar lipid profile (without aminophospholipid) and leucine arylamidase activity. Based on the data of the polyphasic analysis, it is considered that strain NL^T represented a novel species of genus Hymenobacter, for which the name Hymenobacter edaphisp. nov. is proposed. The type strain is NL^T (=KCTC 62521^T=CCTCC AB 2018028^T).

Hymenobacter oligotrophus sp. nov., isolated from a contaminated agar plate

A taxonomic study of a Gram-stain negative, rod-shaped, motile, asporogenous, catalase- and oxidase-positive bacterium, sh-6^T, forming pink-red colonies, isolated from a contaminated R2A plate in the laboratory was performed. Its optimum growth temperature was determined to be 28 °C in the absence of NaCl on R2A plates. On the basis of 16S rRNA gene sequence analysis, strain sh-6^T belongs to the genus Hymenobacter and is closely related to Hymenobacter deserti ZLB-3^T (95.05%), Hymenobacter paludis KBP-30^T (94.96%), Hymenobacter coalescens WW84^T (94.04%), Hymenobacter gummosus ANT-18^T (93.38%), Hymenobacter ocellatus Myx2105^T (93.70%), Hymenobacter jeollabukensis 1-3-3-8^T (93.48%) and Hymenobacter koreensis GYR3077^T (93.21%). Comparison of the genome of strain sh-6^T and that of H. gummosus ANT-18^T gave digital DNA-DNA hybridization and Average Nucleotide Identity values of 20.6% and 78.4%, respectively. The respiratory isoprenoid quinone and polyamine component were identified as MK-7 and sym-homospermidine, respectively. The major cellular fatty acids identified as iso-C_15:0, summed feature 4 (iso-C_17:1 I/anteiso B), iso-C_16:0, iso-C_17:0 3-OH and iso-C_17:0. The major polar lipid of strain sh-6^T determined to be phosphatidylethanolamine. The DNA G+C content was determined to be 60.5 mol%. On the basis of the evidence presented in this study, a novel species of the genus Hymenobacter, Hymenobacter oligotrophus sp. nov., is proposed, with the type strain sh-6^T (= CCTCC AB 2016064^T = KCTC 62345^T).

Hymenobacter metallilatus sp. nov., isolated from abandoned lead-zinc ore

An aerobic, non-motile, Gram-stain-negative, red-to-pinkish and rod-shaped bacterium, designated 9PBR-2^T, was isolated from an abandoned lead-zinc ore sample collected from Meizhou, Guangdong Province, PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 9PBR-2^T belongs to the genus Hymenobacter and was most closely related to Hymenobacter rigui KCTC 12533^T (98.0 %), Hymenobacter swuensis KCTC 32018^T (97.8 %) and Hymenobacter perfusus LMG 26000^T (97.6 %). The calculated average nucleotide identity values based on whole genome sequences between strain 9PBR-2^T and closely related type strains ranged from 81.3 to 84.1 %. Correspondingly, the digital DNA-DNA hybridization values ranged from 25.5 to 28.1 %. The major fatty acids of strain 9PBR-2^T were iso-C15:0, anteiso-C15:0, C16:1ω5c, summed feature 3 (C16:1ω6c and/or C16:1ω7c) and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). It contained menaquinone 7 (MK-7) as the major isoprenoid quinone and phosphatidylethanolamine as the major polar lipid. The genomic DNA G+C content based on whole genome sequence was 59.8 mol%. Characterization based on phylogenetic, chemotaxonomic and phenotypic analyses clearly indicated that strain 9PBR-2^T represents a novel species of the genus Hymenobacter, for which the name Hymenobactermetallilatus sp. nov. is proposed. The type strain is 9PBR-2^T (=GDMCC 1.1492^T=JCM 32699^T).

Hymenobacter persicinus sp. nov., a novel member of the family Hymenobacteraceae

A bacterial strain, 1-3-3-3^T, was isolated from a soil sample collected in Jeollabuk-do province, South Korea. Cells were observed to be Gram-stain negative, short rod-shaped and colonies to be red-pink in colour. Analysis of 16S rRNA gene sequences identified this strain as a member of the genus Hymenobacter in the family Hymenobacteraceae, with high levels of 16S rRNA sequence similarity with Hymenobacter algoricola VUG-A23a^T (98.0%), Hymenobacter knuensis 16F7C-2 (97.9%), Hymenobacter fastidiosus VUG-A124^T (97.1%), Hymenobacter elongatus VUG-A112^T (97.0%), Hymenobacter chitinivorans Txc1^T (97.0%) and Hymenobacter aquaticus 16F3P^T (96.7%). Growth of strain 1-3-3-3^T was observed at 10-30 °C, pH 6-8 and in the presence of 0-1.0% NaCl. The genomic G + C content was determined to be 61.6 mol %. The predominant respiratory quinone of the isolate was found to be MK-7; the major fatty acids were identified as iso-C_15:0 (19.9%), summed feature 3 (C_16:1ω7c/C_16:1ω6c, 19.7%), summed feature 4 (iso-C_17:1 I/anteiso-C_17:1 B, 17.8%), C_16:1ω5c (12.5%) and anteiso-C_15:0 (11.2%), and the major polar lipid was found to be phosphatidylethanolamine. The phenotypic and chemotaxonomic data support the affiliation of strain 1-3-3-3^T with the genus Hymenobacter. However, the DNA-DNA relatedness between the isolate and its closest phylogenetic neighbours was lower than 34%. The DNA-DNA hybridization result and the differentiating phenotypic properties clearly indicate that strain 1-3-3-3^T represents a novel species in the genus Hymenobacter, for which the name Hymenobacter persicinus sp. nov. is proposed. The type strain is 1-3-3-3^T (= KCTC 52742^T = JCM 32191^T).