Description of a new freshwater bacterium Aquirufa regiilacus sp. nov., classification of the genera Aquirufa, Arundinibacter, Sandaracinomonas, and Tellurirhabdus to the family Spirosomataceae, classification of the genus Chryseotalea to the family Fulvivirgaceae and Litoribacter to the family Cyclobacteriaceae, as well as classification of Litoribacter alkaliphilus as a later heterotypic synonym of Litoribacter ruber.

Strains LEOWEIH-7CT and LEPPI-3A were isolated from the Leopoldskroner Weiher, a lake located in the city of Salzburg, Austria. 16S rRNA gene similarities and phylogenetic reconstructions with 16S rRNA gene sequences as well as based on genome sequences revealed that the new strains belong to the A. antheringensis branch of the genus Aquirufa. Calculated whole-genome average nucleotide identity (gANI) and digital DNA-DNA hybridization (dDDH) values with the closely related type strains showed that the two strains represent a single new species. The strains grew aerobically and chemoorganotrophically, and the cells were rod shaped, on average 0.8 µm long and 0.3 µm wide, red pigmented and motile by gliding. The genome size of both strains was 2.6 Mbp and the G+C value was 41.9%. The genomes comprised genes predicted for the complete light-harvesting rhodopsin system and various carotenoids. We proposed to establish the name Aquirufa regiilacus sp. nov. for strain LEOWEIH-7CT (=DSM 116390T = JCM 36347T) as the type strain. Strain LEPPI-3A (=DSM 116391 = JCM 36348) also belongs to this new species. The calculated genome-based phylogenetic tree revealed that Aquirufa and some other genera currently allocated in the family Cytophagaceae need a reclassification. Aquirufa, Arundinibacter, Sandaracinomonas, and Tellurirhabdus should be designated to the family Spirosomataceae, the genus Chryseotalea to the family Fulvivirgaceae, and the genus Litoribacter to the family Cyclobacteriaceae. Furthermore, based on calculated gANI and dDDH values, Litoribacter alkaliphilus should be reclassified as a later heterotypic synonym of Litoribacter ruber.

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.

Pontibacter liquoris sp. nov. and Pontibacter vulgaris sp. nov., two novel bacteria isolated from the pit mud of Chinese liquor.

Two pink-pigmented bacterial strains, designated NBU2971T and NBU2972T, were isolated from the pit mud of a Chinese liquor. Phylogenetic analyses based on 16S rRNA gene sequences suggested that strains NBU2971T and NBU2972T formed a distinct lineage within the family Hymenobacteraceae and were closely related to members of the genus Pontibacter. 16S rRNA gene sequences revealed that strain NBU2971T showed highest similarity of 97.9 % to Pontibacter arcticus 2b14T, and strain NBU2972T showed the highest similarity of 96.9 % to Pontibacter deserti JC215T. The 16S rRNA gene sequence similarity, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two novel strains were 95.2, 73.8 and 19.6 %, respectively, suggesting that they represent different species. The ANI and dDDH values between two novel strains and related species of genus Pontibacter were well below the threshold limit for prokaryotic species delineation. The genomic DNA G+C contents of strains NBU2971T and NBU2972T were 51.3 and 44.5 mol%, respectively. The major cellular fatty acids of the two novel strains were iso-C15 : 0 and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B). The major polar lipid of both novel strains was phosphatidylethanolamine. The only respiratory quinone was MK-7. Combining results of phenotypic, chemotaxonomic and genotypic data, strains NBU2971T and NBU2972T are considered to be two representatives in the genus Pontibacter, which the name Pontibacter liquoris sp. nov. and Pontibacter vulgaris sp. nov. are proposed. The type strains of the new species are NBU2971T (=KCTC 82916T=MCCC 1K06395T) and NBU2972T (=KCTC 82917T=MCCC 1K06396T), respectively.

Characterization of radiation-resistance mechanism in Spirosoma montaniterrae DY10T in terms of transcriptional regulatory system.

To respond to the external environmental changes for survival, bacteria regulates expression of a number of genes including transcription factors (TFs). To characterize complex biological phenomena, a biological system-level approach is necessary. Here we utilized six computational biology methods to infer regulatory network and to characterize underlying biologically mechanisms relevant to radiation-resistance. In particular, we inferred gene regulatory network (GRN) and operons of radiation-resistance bacterium Spirosoma montaniterrae DY10[Formula: see text] and identified the major regulators for radiation-resistance. Our results showed that DNA repair and reactive oxygen species (ROS) scavenging mechanisms are key processes and Crp/Fnr family transcriptional regulator works as a master regulatory TF in early response to radiation.

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).

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

Two novel Gram-negative bacterial strains BT190T 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 BT190T 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 BT190T and BT190 was 99.5%. The strains BT190T and BT191 were closely related to Hymenobacter swuensis DY53T (97.0% 16S rRNA gene similarity), Hymenobacter metallilatus 9PBR-2 T (96.8%), Hymenobacter tibetensis XTM003T (96.8%) and Hymenobacter yonginensis HMD1010T (96.6%). The genome size of strain BT190T was 4,859,864 bp. The DNA G+C content of strain BT190T 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 BT190T and BT191 were raised, smooth, circular and red-pink colored. The sole respiratory quinone of strain BT190T was MK-7 and the predominant cellular fatty acids were iso-C15:0, C16:1 ω5c, summed feature 3 (C16:1 ω6c / C16:1 ω7c) and summed feature 4 (iso-C17:1 I / anteiso-C17:1 B). The major polar lipids of strain BT190T were aminophospholipid (APL) and phosphatidylethanolamine (PE). Based on the chemotaxonomic, biochemical, and phylogenetic analysis, strains BT190T 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 BT190T (= 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 TS19T, 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 WM78T (98.3% similarity). Strain TS19T 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 TS19T 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 TS19T were iso-C15:0, summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B), summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), and C16:1 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 TS19T represents a novel species, for which the name Hymenobacter taeanensis sp. nov. is proposed. The type strain is TS19T (= KCTC 72897T = JCM 34023T).

Hymenobacter guriensis sp. nov., and Hymenobacter duratus sp. nov., Radiation-Resistant Species Isolated from Soil in South Korea.

Two novel Gram-stain-negative, non-motile, aerobic, rod-shaped, circular, convex, red-colored and UV-tolerant strains BT594T and BT646T were isolated from soil collected in Guri city (37° 36' 0″ N, 127° 9' 0″ E) and Gwangju city (37° 22' 0″ N, 127° 17' 0″ E), respectively, South Korea. 16S rDNA sequence analysis indicated that strains BT594T and BT646T belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes, kingdom Bacteria). The 16S rDNA gene sequence similarity between the two strains BT594T and BT646T was 96.2%. The strain BT594T was closely related to Hymenobacter psychrotolerans Tibet-IIU11T (97.0% 16S rDNA gene similarity) and Hymenobacter tibetensis XTM003T (96.3%). The strain BT646T was closely related to Hymenobacter psychrotolerans Tibet-IIU11T (98.6%), Hymenobacter kanuolensis T-3 T (96.8%) and Hymenobacter perfusus LMG 26000 T (96.7%). The two strains were found to have the same quinone system, with MK-7 as the major respiratory quinone. The major polar lipids of strains BT594T and BT646T were phosphatidylethanolamine (PE) and aminophospholipids (APL). The major cellular fatty acids of strain BT594T were anteiso-C15:0 (17.9%), iso-C15:0 (16.1%) and summed feature 3 (C16:1 ω6c / C16:1 ω7c) (10.0%). The major cellular fatty acids of strain BT646T were summed feature 3 (C16:1 ω6c / C16:1 ω7c) (18.3%), C16:0 (17.2%) and summed feature 4 (iso-C17:1 I / anteiso-C17:1 B) (14.5%). Based on the polyphasic analysis, strains BT594T and BT646T can be suggested as two novel bacterial species within the genus Hymenobacter and the proposed names are Hymenobacter guriensis and Hymenobacter duratus, respectively. The type strain of Hymenobacter guriensis is BT594T (= KCTC 21863 T = NBRC 114853 T) and the type strain of Hymenobacter duratus is BT646T (= KCTC 21915 T = NBRC 114854 T).

Morphological change of coiled bacterium Spirosoma linguale with acquisition of ß-lactam resistance.

Spirosoma linguale is a gram-negative, coiled bacterium belonging to the family Cytophagaceae. Its coiled morphology is unique in contrast to closely related bacteria belonging to the genus Spirosoma, which have a short, rod-shaped morphology. The mechanisms that generate unique cell morphology are still enigmatic. In this study, using the Spirosoma linguale ATCC33905 strain, we isolated ß-lactam (cefoperazone and amoxicillin)-resistant clones. These clones showed two different cell morphological changes: relatively loosely curved cells or small, horseshoe-shaped cells. Whole-genome resequencing analysis revealed the genetic determinants of ß-lactam resistance and changes in cell morphology. The loose-curved clones commonly had mutations in Slin_5958 genes encoding glutamyl-tRNA amidotransferase B subunit, whereas the small, horseshoe-shaped clones commonly had mutations in either Slin_5165 or Slin_5509 encoding pyruvate dehydrogenase (PDH) components. Two clones, CFP1ESL11 and CFL5ESL4, which carried only one mutation in Slin_5958, showed almost perfectly straight, rod-shaped cells in the presence of amoxicillin. This result suggests that penicillin-binding proteins targeted by amoxicillin play an important role in the formation of a coiled morphology in this bacterium. In contrast, supplementation with acetate did not rescue the growth defect and abnormal cell size of the CFP5ESL9 strain, which carried only one mutation in Slin_5509. These results suggest that PDH is involved in cell-size maintenance in this bacterium.

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

Two novel Gram-negative bacterial strains BT442T 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 BT442T and BT584 both belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia). Strain BT442T was closely related to Hymenobacter soli PB17T (98.0% 16S rRNA gene similarity) and Hymenobacter terrae POA9T (97.6%). No other recognized bacterial species showed more than 97% 16S rRNA gene sequence similarity to strains BT442T. The genome size of strain BT442T 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 BT442T and BT584 were iso-C15:0, anteiso-C15:0 and summed feature 3 (C16:1 ω6c / C16:1 ω7c). In addition, their predominant respiratory quinone was MK-7. The major polar lipids of strains BT442T and BT584 were identified to be phosphatidylethanolamine, aminophospholipid, and aminolipid. Based on the biochemical, chemotaxonomic, and phylogenetic analyses, strains BT442T and BT584 are novel bacterial species within the genus Hymenobacter, and the proposed name is Hymenobacter negativus. The strain type of Hymenobacter negativus is BT442T (= KCTC 72902T = NBRC XXXXT).

Hymenobacter properus sp. nov., Hymenobacter ruricola sp. nov., and Hymenobacter jeongseonensis sp. nov., three new species isolated from mountain and beach soil in South Korea.

Three Gram-stain-negative, aerobic, circular, convex, red-colored and rod-shaped bacterial strains, designated BT439T, BT662T and BT683T were obtained from soil collected in South Korea. The phylogenetic analysis based on 16S rRNA gene sequences of the strains revealed a distinct lineage within the genus Hymenobacter. The complete genome sequence of strains BT439T, BT662T and BT683T is 5,542,738 bp, 5,964,541 bp, and 5,192,601 bp size, respectively. All three strains were found to have MK-7 as the major respiratory quinone. The major polar lipids of strains BT439T and BT662T were identified as phosphatidylethanolamine, aminophospholipids and amino lipids. Strain BT683T contained phosphatidylethanolamine. The major cellular fatty acids of strain BT439T were iso-C15:0, summed feature 3 (C16:1 ω6c/C16:1 ω7c) and anteiso-C15:0; strain BT662T possessed iso-C15:0 and summed feature 3 (C16:1 ω6c/C16:1 ω7c); strain BT683T were summed feature 3 (C16:1 ω6c/C16:1 ω7c), C16:1 ω5c, iso-C15:0 and anteiso-C15:0. Based on the polyphasic analysis, strains BT439T, BT662T and BT683T can be suggested as three novel bacterial species within the genus Hymenobacter and the proposed names are Hymenobacter properus sp. nov., Hymenobacter ruricola sp. nov. and Hymenobacter jeongseonensis sp. nov., respectively. The type strain of Hymenobacter properus is BT439T (= KCTC 72900T = NBRC 114849T), Hymenobacter ruricola is BT662T (= KACC 21966T = NBRC 114855T) and the type strain of Hymenobacter jeongseonensis is BT683T (= KACC 22013T = NBRC xxxxxT).

Spirosoma profusum sp. nov., and Spirosoma validum sp. nov., radiation-resistant bacteria isolated from soil in South Korea.

Two novel Gram-negative, rod-shaped bacterial strains BT702T and BT704T were isolated from soil collected in Jeongseon (37° 22' 45″ N, 128° 39' 53″ E), Gangwon province, South Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains BT702T and BT704T belong to distinct lineage within the genus Spirosoma (family Cytophagaceae, order Cytophagales, class Cytophagia and phylum Bacteroidetes). The strain BT702T was closely related to Spirosoma flavus 15J11-2T (96.7% 16S rRNA gene similarity) and Spirosoma metallilatum TX0405T (93.3%). The strain BT704T was closely related to Spirosoma koreense 15J8-5T (94.6%), Spirosoma endophyticum DSM 26130T (93.8%) and Spirosoma humi S7-4-1T (93.8%). The genome sizes of type strains BT702T and BT704T are 8,731,341 bp and 8,221,062 bp, respectively. The major cellular fatty acids of strains BT702T and BT704T were C16:1 ω5c and summed feature 3 (C16:1 ω6c/C16:1 ω7c). The strains were found to have the same quinone system, with MK-7 as the major respiratory quinone. The major polar lipids of strain BT702T was identified to be phosphatidylethanolamine (PE), aminophospholipid (APL) and aminolipid (AL), while that of strain BT704T consisted of phosphatidylethanolamine (PE) and aminophospholipid (APL). Based on the polyphasic analysis (phylogenetic, chemotaxonomic and biochemical), strains BT702T and BT704T can be suggested as two new bacterial species within the genus Spirosoma and the proposed names are Spirosoma profusum and Spirosoma validum, respectively. The type strain of Spirosoma profusum is BT702T (= KCTC 82115T = NBRC 114859T) and type strain of Spirosoma validum is BT704T (= KCTC 82114T = NBRC 114966T).

Assessing the efficacy of eDNA metabarcoding for measuring microbial biodiversity within forest ecosystems.

We investigated the nascent application and efficacy of sampling and sequencing environmental DNA (eDNA) in terrestrial environments using rainwater that filters through the forest canopy and understory vegetation (i.e., throughfall). We demonstrate the utility and potential of this method for measuring microbial communities and forest biodiversity. We collected pure rainwater (open sky) and throughfall, successfully extracted DNA, and generated over 5000 unique amplicon sequence variants. We found that several taxa including Mycoplasma sp., Spirosoma sp., Roseomonas sp., and Lactococcus sp. were present only in throughfall samples. Spiroplasma sp., Methylobacterium sp., Massilia sp., Pantoea sp., and Sphingomonas sp. were found in both types of samples, but more abundantly in throughfall than in rainwater. Throughfall samples contained Gammaproteobacteria that have been previously found to be plant-associated, and may contribute to important functional roles. We illustrate how this novel method can be used for measuring microbial biodiversity in forest ecosystems, foreshadowing the utility for quantifying both prokaryotic and eukaryotic lifeforms. Leveraging these methods will enhance our ability to detect extant species, describe new species, and improve our overall understanding of ecological community dynamics in forest ecosystems.

Pontibacter fetidus sp. nov. and Pontibacter burrus sp. nov., isolated from the soil.

Two novel strains, BT213T and BT327T, were isolated from the soil collected in Uijeongbu city, Korea. Cells of strains were Gram negative, aerobic, and non-motile. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains BT213T and BT327T formed two distinct lineages within the family Hymenobacteraceae (order Cytophagales, class Cytophagia). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BT213T and BT327T belonged to the genus Pontibacter. Strain BT213T showed the highest similarities of 97.8% with Pontibacter deserti JC215T. Strain BT327T showed the highest sequence similarity of 96.5% with Pontibacter mucosus PB3T. Optimal growth occurred at 25 °C, pH 7, and in the absence of NaCl. The major cellular fatty acid of strains BT213T and BT327T were iso-C15:0 and summed feature 4 (iso-C17:1 I/anteiso-C17:1 B). Strains BT213T and BT327T had MK-7 as major respiratory quinone and phosphatidylethanolamine as major polar lipids. The genome size of strains BT213T and BT327T were 4,072,018 bp and 4,314,171 bp, respectively. The genomic G + C mol% of strains BT213T and BT327T are 45.6% and 46.1%, respectively. Based on biochemical, chemotaxonomic, and phylogenetic analysis, two novel species Pontibacter fetidus BT213T (KCTC 72345T = NBRC 114379T) and Pontibacter burrus BT327T (KCTC 72412T = NBRC 114376T) are proposed as type strains.

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

A bacterial strain, designated 17J36-26T, 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 17J36-26T were summed feature 4 (17:1 iso I/17:1 anteiso B), summed feature 3 (16:1 ω6c/16:1 ω7c), C16:1 ω5c and iso-C15:0. The polar lipid profile contained phosphatidylethanolamine, unidentified aminophospholipid, phospholipids and four unidentified lipids. The G+C content of the strain 17J36-26T was 62.6 mol%. The 16S rRNA gene sequence analysis showed that strain 17J36-26T was phylogenetically related to Hymenobacter qilianensis DK6-37T and Hymenobacter roseosalivarius AA718T (97.5% and 96.8% sequence similarity, respectively). Strain 17J36-26T showed resistance to UV radiation. Both average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between strains 17J36-26T 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 17J36-26T 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 17J36-26T = KCTC 62269T = JCM 33185T) is proposed.

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

Two bacterial strains designated as MA3T 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 NLT, followed by Hymenobacter paludis KBP-30T (96.3%), Hymenobacter coalescens WW84T (96.3%) and Hymenobacter gummosus ANT-18T (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 MA3T 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-C15:0, iso-C15:0, summed feature 4 (iso-C17:1 I/anteiso-C17:1 B) and summed feature 3 (C16:1 ω6c/C16:1 ω7c), supporting the affiliation of these strains with the genus Hymenobacter. Based on the phylogenetic, genotypic, phenotypic and chemotaxonomic data, strains MA3T and BT182 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter busanensis is proposed. The type strain is MA3T (= KCTC 72631T = NBRC 114193T).

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 BT328T and Gram-stain-negative, aerobic, non-motile, red-colored strain BT18T were isolated from the soil collected in Korea. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain BT328T 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 15J9-4T (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 (C16:1 ω6c/C16:1 ω7c) and C16:1 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 BT18T 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-2T (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-C15:0 and anteiso-C15:0. The major menaquinone was MK-7. The major polar lipid was phosphatidylethanolamine. Biochemical, chemotaxonomic and phylogenetic analyses indicated that strains BT328T and BT18T 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 BT328T (=KCTC 72365T = NBRC 114506T) and the type strain of H. russus is BT18T (=KCTC 62610T = NBRC 114380T).

Rhodocytophaga rosea sp. nov. and Nibribacter ruber sp. nov., two radiation-resistant bacteria isolated from soil.

Two bacterial strains, 172606-1T and BT10T, were isolated from soil, Korea. Both strains were Gram-stain-negative and rod-shaped bacteria. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 172606-1T formed a distinct lineage within the family Cytophagaceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes). Strain 172606-1T was most closely related to a member of the genus Rhodocytophaga (93.8% 16S rRNA gene sequence similarity to Rhodocytophaga aerolata 5416T-29T). The complete genome sequence of strain 172606-1T is 8,983,451 bp size. Optimal growth occurred at 25 °C and pH 7.0 without NaCl. The major cellular fatty acids were identified as iso-C15:0 and C16:1 ω5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain BT10T belongs to the genus Nibribacter and is closely related to Nibribacter koreensis GSR 3061T (96.5%), Rufibacter glacialis MDT1-10-3T (95.7%), Rufibacter sediminis H-1T (95.1%) and Rufibacter quisquiliarum CAI-18bT (94.9%). The complete genome sequence of strain BT10T is 4,374,810 bp size. The predominant (> 10%) cellular fatty acids of strain BT10T were iso-C15:0 and summed feature 4 (anteiso-C17:1 B/iso-C17:1 I) and a predominant quinone was MK-7. In addition, strain BT10T has phosphatidylethanolamine (PE) as the major polar lipid. On the basis of biochemical, chemotaxonomic and phylogenetic analyses, strain 172606-1T represents a novel bacterial species of the genus Rhodocytophaga, for which the name Rhodocytophaga rosea is proposed and strain BT10T represents a novel species of the genus Nibribacter, for which the name Nibribacter ruber is proposed. The type strains of Rhodocytophaga rosea and Nibribacter ruber are 172606-1T (= KCTC 62096T = NBRC 114410T) and BT10T (= KCTC 62607T = NBRC 114383T), respectively.

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.

Larkinella punicea sp. nov., isolated from manganese mine soil.

Strain ZZJ9T is a Gram-stain-negative, rod-shaped, aerobic bacterium isolated from manganese mine soil. Strain ZZJ9T showed the highest 16S rRNA gene sequence similarities with Larkinella rosea 15J16-1T3AT (97.1%), Larkinella terrae 15J8-8T (97.0%), Larkinella knui 15J6-3T6T (96.8%), and Larkinella ripae 15J11-1T (95.3%). The genome size of strain ZZJ9T was 8.01 Mb and the DNA G+C content was 51.8 mol%. ANI values among strain ZZJ9T and Larkinella rosea 52004 T, Larkinella knui KCTC 42998T, and Larkinella terrae 52001T were 80.5%, 82.7%, and 80.5%, respectively. dDDH values among strain ZZJ9T and Larkinella rosea 52004T, Larkinella knui KCTC 42998T, and Larkinella terrae 52001T were 23.5%, 26.0%, and 23.6%, respectively. Furthermore, the genome of strain ZZJ9T contained 6302 predicted protein-coding genes and 3114 (49%) of them had classificatory functions. The major quinone of strain ZZJ9T was menaquinone-7 and the main cellular fatty acids were C16:1ω5c (39.5%), iso-C15:0 (25.6%), and iso-C17:0 3OH (11.5%). The polar lipids of strain ZZJ9T were phosphatidylethanolamine, unidentified lipid, and two unidentified aminolipids. Based on the results of phylogenetic, genome, phenotypic, and chemotaxonomic analytical, strain ZZJ9T represents a novel species of the genus Larkinella, for which the name Larkinella punicea sp. Nov. is proposed. The type strain is ZZJ9T (= KCTC 62876T = CCTCC AB 2018215T).