Deinococcus rhizophilus sp.nov., isolated from rhizosphere soil

A spherical, pink, aerobic, Gram-stain-positive bacterial strain (MIMF12T) was isolated from rhizosphere soil collected in the Inner Mongolia Autonomous Region, PR China. Cellular growth of the strain was observed at pH 6.0-8.0 (optimum, pH 7.0), at 20-37 °C (optimum, 28 °C) and with 0-1 % (w/v) NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain MIMF12T was most closely related to Deinococcus terrestris SDU3-2T with a similarity value of 96.0 %. The respiratory quinone was menaquinone 8, the major fatty acids were C15 : 1  ω6c and C17 : 1  ω8c, and the major polar lipids were composed of two aminophospholipids, one phospholipid and four unidentified lipids. The G+C content of the genomic DNA was 70.1 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain MIMF12T and the closest related type strain SDU3-2T were 88.1 and 52.1 %, respectively. The discovery that MIMF12T differs not only from validly named species in the genus Deinococcus, but also from currently unnamed species in the GDTB, gives us new insights into the genus. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, strain MIMF12T represents a novel species of the genus Deinococcus, for which the name Deinococcus rhizophilus sp. nov. is proposed. The type strain is MIMF12T (=CGMCC 1.61579T=KCTC 43572T).

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).

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.

Characterisation of Waterborne Psychrophilic Massilia Isolates with Violacein Production and Description of Massilia antarctica sp. nov

A group of seven bacterial strains producing blue-purple pigmented colonies on R2A agar was isolated from freshwater samples collected in a deglaciated part of James Ross Island and Eagle Island, Antarctica, from 2017–2019. The isolates were psychrophilic, oligotrophic, resistant to chloramphenicol, and exhibited strong hydrolytic activities. To clarify the taxonomic position of these isolates, a polyphasic taxonomic approach was applied based on sequencing of the 16S rRNA, gyrB and lepA genes, whole-genome sequencing, rep-PCR, MALDI-TOF MS, chemotaxonomy analyses and biotyping. Phylogenetic analysis of the 16S rRNA gene sequences revealed that the entire group are representatives of the genus Massilia. The closest relatives of the reference strain P8398T were Massilia atriviolacea, Massilia violaceinigra, Massilia rubra, Massilia mucilaginosa, Massilia aquatica, Massilia frigida, Massilia glaciei and Massilia eurypsychrophila with a pairwise similarity of 98.6–100% in the 16S rRNA. The subsequent gyrB and lepA sequencing results showed the novelty of the analysed group, and the average nucleotide identity and digital DNA–DNA hybridisation values clearly proved that P8398T represents a distinct Massilia species. After all these results, we nominate a new species with the proposed name Massilia antarctica sp. nov. The type strain is P8398T (= CCM 8941T = LMG 32108T).

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).

Classification of a Violacein-Producing Psychrophilic Group of Isolates Associated with Freshwater in Antarctica and Description of Rugamonas violacea sp. nov

A group of 11 bacterial strains was isolated from streams and lakes located in a deglaciated northern part of James Ross Island, Antarctica. They were rod-shaped, Gram-stain-negative, motile, and catalase-positive and produced blue-violet-pigmented colonies on R2A agar. A polyphasic taxonomic approach based on 16S rRNA gene sequencing, whole-genome sequencing, automated ribotyping, repetitive element sequence-based PCR (rep-PCR), MALDI-TOF MS, fatty acid profile, chemotaxonomy analyses, and extensive biotyping was applied in order to clarify the taxonomic position of these isolates. Phylogenetic analysis based on the 16S rRNA gene indicated that all the isolates constituted a coherent group belonging to the genus Rugamonas. The closest relatives to the representative isolate P5900T were Rugamonas rubra CCM 3730T, Rugamonas rivuli FT103WT, and Rugamonas aquatica FT29WT, exhibiting 99.2%, 99.1%, and 98.6% 16S rRNA pairwise similarity, respectively. The average nucleotide identity and digital DNA-DNA hybridization values calculated from the whole-genome sequencing data clearly proved that P5900T represents a distinct Rugamonas species. The G+C content of genomic DNAs was 66.1 mol%. The major components in fatty acid profiles were summed feature 3 (C16:1ω7c/C16:1ω6c), C 16:0, and C12:0. The cellular quinone content contained exclusively ubiquinone Q-8. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The polyamine pattern was composed of putrescine, 2-hydroxputrescine, and spermidine. IMPORTANCE Our polyphasic approach provides a new understanding of the taxonomy of novel pigmented Rugamonas species isolated from freshwater samples in Antarctica. The isolates showed considerable extracellular bactericidal secretions. The antagonistic activity of studied isolates against selected pathogens was proved by this study and implied the importance of such compounds' production among aquatic bacteria. The psychrophilic and violacein-producing species Roseomonas violacea may play a role in the diverse consortium among pigmented bacteria in the Antarctic water environment. Based on all the obtained results, we propose a novel species for which the name Rugamonas violacea sp. nov. is suggested, with the type strain P5900T (CCM 8940T; LMG 32105T). Isolates of R. violacea were obtained from different aquatic localities, and they represent the autochthonous part of the water microbiome in Antarctica.

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).

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.

Description of Massilia rubra sp. nov., Massilia aquatica sp. nov., Massilia mucilaginosa sp. nov., Massilia frigida sp. nov., and one Massilia genomospecies isolated from Antarctic streams, lakes and regoliths

Bacteria of the genus Massilia often colonize extreme ecosystems, however, a detailed study of the massilias from the Antarctic environment has not yet been performed. Here, sixty-four Gram-stain-negative, aerobic, motile rods isolated from different environmental samples on James Ross Island (Antarctica) were subjected to a polyphasic taxonomic study. The psychrophilic isolates exhibited slowly growing, moderately slimy colonies revealing bold pink-red pigmentation on R2A agar. The set of strains exhibited the highest 16S rRNA gene sequence similarities (99.5-99.9%) to Massilia violaceinigra B2^T and Massilia atriviolacea SOD^T and formed several phylogenetic groups based on the analysis of gyrB and lepA genes. Phenotypic characteristics allowed four of them to be distinguished from each other and from their closest relatives. Compared to the nearest phylogenetic neighbours the set of six genome-sequenced representatives exhibited considerable phylogenetic distance at the whole-genome level. Bioinformatic analysis of the genomic sequences revealed a high number of putative genes involved in oxidative stress response, heavy-metal resistance, bacteriocin production, the presence of putative genes involved in nitrogen metabolism and auxin biosynthesis. The identification of putative genes encoding aromatic dioxygenases suggests the biotechnology potential of the strains. Based on these results four novel species and one genomospecies of the genus Massilia are described and named Massilia rubra sp. nov. (P3094^T=CCM 8692^T=LMG 31213^T), Massilia aquatica sp. nov. (P3165^T=CCM 8693^T=LMG 31211^T), Massilia mucilaginosa sp. nov. (P5902^T=CCM 8733^T=LMG 31210^T), and Massilia frigida sp. nov. (P5534^T=CCM 8695^T=LMG 31212^T).

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).

Pseudomonas leptonychotis sp. nov., isolated from Weddell seals in Antarctica

A taxonomic study was carried out on four Gram-stain-negative strains P5773^T, P6169, P4708 and P6245, isolated from anus or mouth samples of Weddell seals at James Ross Island, Antarctica. The results of initial 16S rRNA gene sequence analysis showed that all four strains formed a group placed in the genus Pseudomonas and found Pseudomonas guineae and Pseudomonas peli to be their closest neighbours with 99.9 and 99.2 % sequence similarity, respectively. Sequence analysis of rpoD, rpoB and gyrB housekeeping genes confirmed the highest similarity of isolates to P. peli (rpoD) and to P. guineae (rpoB and gyrB). The average nucleotide identity value below 86 %, as calculated from the whole-genome sequence data, showed the low genomic relatedness of P5773^T to its phylogenetic neighbours. The complete genome of strain P5773^T was 4.4 Mb long and contained genes encoding proteins with biotechnological potential. The major fatty acids of the seal isolates were summed feature 8 (C_18 : 1 ω7c), summed feature 3 (C_16 : 1 ω 7 c/C_{16  : 1} ω6c) and C_16:0. The major respiratory quinone was Q9. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Putrescine and spermidine are predominant in the polyamine pattern. Further characterization performed using repetitive sequence-based PCR fingerprinting and MALDI-TOF MS analysis showed that the studied isolates formed a coherent cluster separated from the remaining Pseudomonas species and confirmed that they represent a novel species within the genus Pseudomonas, for which the name Pseudomonas leptonychotis sp. nov. is suggested. The type strain is P5773^T (=CCM 8849^T=LMG 30618^T).

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).

Antarctic heterotrophic bacterium Hymenobacter nivis P3T displays light-enhanced growth and expresses putative photoactive proteins

Hymenobacter nivis P3^T is a heterotrophic bacterium isolated from Antarctic red snow generated by algal blooms. Despite being non-photosynthetic, H. nivis was dominantly found in the red snow environment that is exposed to high light and UV irradiation, suggesting that this species can flourish under such harsh conditions. In order to further understand the adaptive strategies on the snow surface environment of Antarctica, the genome of H. nivis P3^T was sequenced and analyzed, which identified genes putatively encoding for light-reactive proteins such as proteorhodopsin, phytochrome, photolyase and several copies of cryptochromes. Culture-based experiments revealed that H. nivis P3^T growth was significantly enhanced under light conditions, while dark conditions had increased extracellular polymeric substances. Furthermore, the expression of several putative light-reactive proteins was determined by proteomic analysis. These results indicate that H. nivis P3^T is able to potentially utilize light, which may explain its dominance on the red snow surface environment of Antarctica. ORIGINALITY-SIGNIFICANCE STATEMENT: The role of proteorhodopsin in heterotrophic bacteria is not well-characterized, as only a handful of proteorhodopsin-harbouring isolates were shown to have a light-enhanced phenotype through culture-based experiments to date. This is the first study that demonstrates light-stimulated growth and protein expression evidence of photoactive proteins for a non-marine psychrophile and for a member of the genus Hymenobacter. It is also the first study that provides comprehensive proteome information for this genus. This study presents significant results in understanding the adaptive mechanism of a heterotrophic non-photosynthetic bacterium thriving on the snow surface environment of Antarctica as well as demonstrating the role of light-utilization in promoting growth, possibly through proteorhodopsin.

Hymenobacter crusticola sp. nov., isolated from biological soil crust

A Gram-stain-negative, aerobic, light-pink, short rod-shaped, non-spore-forming bacterial strain was isolated from biological soil crust sampled in the Hopq Desert, Inner Mongolia, China, designated MIMBbqt21^T. The G+C content of the genomic DNA was 55.1 mol%. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain MIMBbqt21^T belonged to the genus Hymenobacter and had the highest sequence similarity to Hymenobacter cavernaeK1E01-27^T (94.35 %). Cell growth could be observed at 4-29 °C (optimum, 24 °C), pH of 6.0-8.6 (optimum, 6.0) and in the presence of 1 % (w/v) NaCl (optimum, 0 %). The major fatty acids of strain MIMBbqt21^T were iso-C15 : 0, C16 : 1ω5c and summed feature 3 (C16 : 1ω7c/C16 : 1ω6c). The main polar lipids were phosphatidylethanolamine, five unidentified aminophospholipids, an unidentified glycolipid and four unidentified polar lipids. The sole respiratory quinone was menaquinone MK-7. Based on the results of the phylogenetic, chemotaxonomic and phenotypic studies, strain MIMBbqt21^T could be distinguished from all known Hymenobacter species and represents a novel species, for which the name Hymenobactercrusticola sp. nov. is proposed. The type strain is MIMBbqt21^T (=MCCC 1K01312^T=KCTC 42804^T).

Hymenobacter jeollabukensis sp. nov., isolated from soil

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterial strain, designated 1-3-3-8^T, was isolated from soil and characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain 1-3-3-8^T belongs to the family Cytophagaceae of phylum Bacteroidetes and is most closely related to Hymenobacter paludis KBP-30^T (96.8% similarity), Hymenobacter ocellatus Myx2105^T (96.8%), Hymenobacter coalescens WW84^T (95.6%), and Hymenobacter deserti ZLB-3^T (95.4%). The G + C content of the genomic DNA of strain 1-3-3-8^T was 63.6 mol%. The isolate contained C_15:0 iso (28.4%), summed feature 4 (C_17:1 anteiso B/C_17:1 iso I; 18.9%), and C_15:0 anteiso (17.6%) as major fatty acids, MK-7 as the predominant respiratory quinone, and sym-homospermidine as the predominant polyamine. The major polar lipids were phosphatidylethanolamine and an unidentified lipid. The phenotypic and chemotaxonomic data supported the affiliation of strain 1-3-3-8^T with the genus Hymenobacter. The DNA-DNA relatedness between strain 1-3-3-8^T and H. paludis KCTC 32237^T and H. ocellatus DSM 11117^T were 24.5 and 27.4% respectively, clearly showing that the isolate is not related to them at the species level. Overall, the novel strain could be differentiated from its phylogenetic neighbors on the basis of several phenotypic, genotypic, and chemotaxonomic features. Therefore, strain 1-3-3-8^T represents a novel species of the genus Hymenobacter, for which the name Hymenobacter jeollabukensis sp. nov. has been proposed. The type strain is 1-3-3-8^T (= KCTC 52741^T = JCM 32192^T).

Hymenobacter segetis sp. nov., isolated from soil

A polyphasic taxonomic study was performed on a novel strain designated as S7-3-11^T, which was isolated from soil of the Gyeongsangnam-do province in Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain S7-3-11^T belongs to the genus Hymenobacter and is most closely related to Hymenobacter ruber PB156^T (97.9%), Hymenobacter daeguensis 16F3Y-2^T (97.8%), Hymenobacter glaciei VUG-A130^T (97.7%), Hymenobacter soli PB17^T (97.5%), Hymenobacter terrae DG7A^T (97.5%), and Hymenobacter antarcticus VUG-A42aa^T (97.3%). However, DNA-DNA hybridization results showed less than 50% relatedness with respect to the type strains of the six most closely related species. The DNA G + C content of strain S7-3-11^T was 60.2 mol%. MK-7 was identified as the predominant respiratory quinone, and summed feature 3 (C_16:1 ω7c/C_16:1 ω6c; 21.5%), C_15:0 iso (16.8%), C_15:0 anteiso (16.2%), and C_15:1 iso G (10.8%) were the major fatty acids. Phosphatidylethanolamine, an unidentified aminolipid, and an unidentified aminophospholipid were detected as major polar lipids. On the basis of the polyphasic evidence presented, strain S7-3-11^T is considered to represent a novel species of the genus Hymenobacter, for which the name Hymenobacter segetis sp. nov. is proposed. The type strain is S7-3-11^T (= KCTC 52732^T = JCM 32197^T).

Hymenobacter pedocola sp. nov., a novel bacterium isolated from soil

Strain S12-2-1^T was isolated from a soil sample collected in the Gyeongsangnam-do province of the Republic of Korea. The isolate is a Gram-stain-negative, aerobic, short, rod-shaped bacterium, and its colonies are red to pink in colour. Analysis of the 16S rRNA gene identified strain S12-2-1^T as a member of the genus Hymenobacter in the family Cytophagaceae, with high levels of 16S rRNA gene sequence similarity to Hymenobacter arizonensis OR362-8^T (97.7 %), Hymenobacter sedentarius DG5B^T (97.4 %) and Hymenobacter humi DG31A^T (97.2 %). The isolate was positive for catalase and oxidase, but negative for acid production from glucose. The growth of strain S12-2-1^T was supported at 4-30 °C, pH 7-10 and in the presence of 0-0.5 % NaCl. Strain S12-2-1^T contained menaquinone-7 as the predominant respiratory quinone, sym-homospermidine as the major polyamine and iso-C15 : 0, anteiso-C15 : 0 and summed feature 3 (C16 : 1ω7c/C16 : 1ω6c) as the major fatty acids. Phosphatidylethanolamine was the major polar lipid. The genomic DNA G+C content was 58.7 mol%. Phenotypic and chemotaxonomic data supported the assignment of the isolate to the genus Hymenobacter. However, strain S12-2-1^T exhibited a relatively low level of DNA-DNA relatedness with H. humi (31.7 %), H. arizonensis (24.4 %) and H. sedentarius (21.3 %). Based on its phenotypic and genotypic properties, along with its phylogenetic distinctiveness, strain S12-2-1^T should be considered a novel species in the genus Hymenobacter, for which the name Hymenobacter pedocola sp. nov. is proposed. The type strain is S12-2-1^T (=KCTC 52730^T=JCM 32198^T).

Hymenobacter profundi sp. nov., isolated from deep-sea water

A Gram-stain-negative, rod-shaped, red-pigmented, aerobic bacterium, strain M2^T, was isolated from a seawater sample collected from the western Pacific Ocean at a depth of 1000 m and characterized using polyphasic taxonomy. Strain M2^T was catalase-positive and oxidase-negative. Cells grew at 4-33 °C (optimum, 25 °C), at pH 6-9 (optimum, 7) and with 0-4 % (w/v) (optimum, 1 %) NaCl. Phylogenetic trees based on 16S rRNA gene sequences showed that strain M2^T was associated with the genus Hymenobacter. Strain M2^T showed the highest 16S rRNA gene sequence similarities to Hymenobacter actinosclerus CCUG 39621^T (95.7 %), Hymenobacter tibetensis XTM003^T (95.6 %) and Hymenobacter psychrotolerans Tibet-IIU11^T (95.2 %). The DNA G+C content was 59.98 mol%. Strain M2^T contained C_16 : 1ω5c (25.0 %), iso-C_15 : 0 (23.9 %) and summed feature 3 (C_16 : 1ω6c and/or C_16 : 1ω7c, 20.4 %) as major cellular fatty acids. The major quinone of strain M2^T was menaquinone 7 and the major polar lipid was phosphatidylethanolamine. The major polyamine of strain M2^T was sym-homospermidine. The phylogenetic analysis and physiological and biochemical data showed that strain M2^T should be classified as representing a novel species of the genus Hymenobacter, for which the name Hymenobacter profundi sp. nov. is proposed. The type strain is M2^T (=CCTCC AB 2017185^T=KCTC 62120^T).