Life under the snow: A year-round transcriptome analysis of Antarctic mosses in natural habitats provides insight into the molecular adaptation of plants under extreme environment.

Mosses are vital components of ecosystems, exhibiting remarkable adaptability across diverse habitats from deserts to polar ice caps. Sanionia uncinata (Hedw.) Loeske, a dominant Antarctic moss survives extreme environmental condition through perennial lifecycles involving growth and dormancy alternation. This study explores genetic controls and molecular mechanisms enabling S. uncinata to cope with seasonality of the Antarctic environment. We analysed the seasonal transcriptome dynamics of S. uncinata collected monthly from February 2015 to January 2016 in King George Island, Antarctica. Findings indicate that genes involved in plant growth were predominantly upregulated in Antarctic summer, while those associated with protein synthesis and cell cycle showed marked expression during the winter-to-summer transition. Genes implicated in cellular stress and abscisic acid signalling were highly expressed in winter. Further, validation included a comparison of the Antarctic field transcriptome data with controlled environment simulation of Antarctic summer and winter temperatures, which revealed consistent gene expression patterns in both datasets. This proposes a seasonal gene regulatory model of S. uncinate to understand moss adaptation to extreme environments. Additionally, this data set is a valuable resource for predicting genetic responses to climatic fluctuations, enhancing our knowledge of Antarctic flora's resilience to global climate change.

Temperature sensitivity of Antarctic soil-humic substance degradation by cold-adapted bacteria.

Heteropolymer humic substances (HS) are the largest constituents of soil organic matter and are key components that affect plant and microbial growth in maritime Antarctic tundra. We investigated HS decomposition in Antarctic tundra soils from distinct sites by incubating samples at 5°C or 8°C (within a natural soil thawing temperature range of -3.8°C to 9.6°C) for 90 days (average Antarctic summer period). This continuous 3-month artificial incubation maintained a higher total soil temperature than that in natural conditions. The long-term warming effects rapidly decreased HS content during the initial incubation, with no significant difference between 5°C and 8°C. In the presence of Antarctic tundra soil heterogeneity, the relative abundance of Proteobacteria (one of the major bacterial phyla in cold soil environments) increased during HS decomposition, which was more significant at 8°C than at 5°C. Contrasting this, the relative abundance of Actinobacteria (another major group) did not exhibit any significant variation. This microcosm study indicates that higher temperatures or prolonged thawing periods affect the relative abundance of cold-adapted bacterial communities, thereby promoting the rate of microbial HS decomposition. The resulting increase in HS-derived small metabolites will possibly accelerate warming-induced changes in the Antarctic tundra ecosystem.

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.

Lichenicola cladoniae gen. nov., sp. nov., a member of the family Acetobacteraceae isolated from an Antarctic lichen.

Two Gram-stain-negative, facultative anaerobic, chemoheterotrophic, pink-coloured, rod-shaped and non-motile bacterial strains, PAMC 26568 and PAMC 26569T, were isolated from an Antarctic lichen. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains PAMC 26568 and PAMC 26569T belong to the family Acetobacteraceae and the most closely related species are Gluconacetobacter takamatsuzukensis (96.1 %), Gluconacetobacter tumulisoli (95.9 %) and Gluconacetobacter sacchari (95.7 %). Phylogenomic and genomic relatedness analyses showed that strains PAMC 26568 and PAMC 26569T are clearly distinguished from other genera in the family Acetobacteraceae by average nucleotide identity values (<72.8 %) and the genome-to-genome distance values (<22.5 %). Genomic analysis revealed that strains PAMC 26568 and PAMC 26569T do not contain genes involved in atmospheric nitrogen fixation and utilization of sole carbon compounds such as methane and methanol. Instead, strains PAMC 26568 and PAMC 26569T possess genes to utilize nitrate and nitrite and certain monosaccharides and disaccharides. The major fatty acids (>10 %) are summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c; 40.3-40.4 %), C18 : 1 2OH (22.7-23.7 %) and summed feature 2 (C14 : 0 3OH and/or C16 : 1 iso I; 12.0 % in PAMC 26568). The major respiratory quinone is Q-10. The genomic DNA G+C content of PAMC 26568 and PAMC 26569T is 64.6 %. Their distinct phylogenetic position and some physiological characteristics distinguish strains PAMC 26568 and PAMC 26569T from other genera in the family Acetobacteraceae supporting the proposal of Lichenicola gen. nov., with the type species Lichenicola cladoniae sp. nov. (type strain, PAMC 26569T=KCCM 43315T=JCM 33604T).

Lichenihabitans psoromatis gen. nov., sp. nov., a member of a novel lineage (Lichenihabitantaceae fam. nov.) within the order of Rhizobiales isolated from Antarctic lichen.

Two Gram-stain-negative, facultative anaerobic chemoheterotrophic, pink-coloured, rod-shaped and non-motile bacterial strains, PAMC 29128 and PAMC 29148T, were isolated from lichen. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strains PAMC 29128 and PAMC 29148T belong to lichen-associated Rhizobiales-1 (LAR1), an uncultured phylogenetic lineage of the order Rhizobiales and the most closely related genera were Methylocapsa (<93.9 %) and Methylosinus (<93.8 %). The results of phylogenomic and genomic relatedness analyses also showed that strains PAMC 29128 and PAMC 29148T were clearly distinguished from other species in the order Rhizobiales with average nucleotide identity values of <71.4 % and genome-to-genome distance values of <22.7 %. Genomic analysis revealed that strains PAMC 29128 and PAMC 29148T did not contain genes involved in atmospheric nitrogen fixation or utilization of carbon compounds such as methane and methanol. Strains PAMC 29128 and PAMC 29148T were able to utilize certain monosaccharides, disaccharides, sugar alcohols and other organic compounds as a sole carbon source. The major fatty acids (>10 %) were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c; 33.7-39.7 %), summed feature 3 (C16 : 1 ω7c and/or C 16:1 ω6c; 25.2-25.4 %) and C19 :0 cyclo ω8c (11.9-15.4 %). The major respiratory quinone was Q-10. The genomic DNA G+C contents of PAMC 29128 and PAMC 29148T were 63.0 and 63.1 mol%, respectively. Their distinct phylogenetic position and some physiological characteristics support the proposal of Lichenihabitans gen. nov., with the type species Lichenihabitans psoromatis sp. nov. (type strain, PAMC 29148T=KCCM 43293T=JCM 33311T). Lichenihabitantaceae fam. nov. is also proposed.

Passive warming effect on soil microbial community and humic substance degradation in maritime Antarctic region.

Although the maritime Antarctic has undergone rapid warming, the effects on indigenous soil-inhabiting microorganisms are not well known. Passive warming experiments using open-top chamber (OTC) have been performed on the Fildes Peninsula in the maritime Antarctic since 2008. When the soil temperature was measured at a depth of 2-5 cm during the 2013-2015 summer seasons, the mean temperature inside OTC (OTC-In) increased by approximately 0.8 °C compared with outside OTC (OTC-Out), while soil chemical and physical characteristics did not change. Soils (2015 summer) from OTC-In and OTC-Out were subjected to analysis for change in microbial community and degradation rate of humic substances (HS, the largest pool of recalcitrant organic carbon in soil). Archaeal and bacterial communities in OTC-In were minimally affected by warming compared with those in OTC-Out, with archaeal methanogenic Thermoplasmata slightly increased in abundance. The abundance of heterotrophic fungi Ascomycota was significantly altered in OTC-In. Total bacterial and fungal biomass in OTC-In increased by 20% compared to OTC-Out, indicating that this may be due to increased microbial degradation activity for soil organic matter (SOM) including HS, which would result in the release of more low-molecular-weight growth substrates from SOM. Despite the effects of warming on the microbial community over the 8-years-experiments warming did not induce any detectable change in content or structure of polymeric HS. These results suggest that increased temperature may have significant and direct effects on soil microbial communities inhabiting maritime Antarctic and that soil microbes would subsequently provide more available carbon sources for other indigenous microbes.

Geographical structure of endosymbiotic bacteria hosted by Bathymodiolus mussels at eastern Pacific hydrothermal vents.

BACKGROUND: Chemolithoautotrophic primary production sustains dense invertebrate communities at deep-sea hydrothermal vents and hydrocarbon seeps. Symbiotic bacteria that oxidize dissolved sulfur, methane, and hydrogen gases nourish bathymodiolin mussels that thrive in these environments worldwide. The mussel symbionts are newly acquired in each generation via infection by free-living forms. This study examined geographical subdivision of the thiotrophic endosymbionts hosted by Bathymodiolus mussels living along the eastern Pacific hydrothermal vents. High-throughput sequencing data of 16S ribosomal RNA encoding gene and fragments of six protein-coding genes of symbionts were examined in the samples collected from nine vent localities at the East Pacific Rise, Galápagos Rift, and Pacific-Antarctic Ridge. RESULTS: Both of the parapatric sister-species, B. thermophilus and B. antarcticus, hosted the same numerically dominant phylotype of thiotrophic Gammaproteobacteria. However, sequences from six protein-coding genes revealed highly divergent symbiont lineages living north and south of the Easter Microplate and hosted by these two Bathymodiolus mussel species. High heterogeneity of symbiont haplotypes among host individuals sampled from the same location suggested that stochasticity associated with initial infections was amplified as symbionts proliferated within the host individuals. The mussel species presently contact one another and hybridize along the Easter Microplate, but the northern and southern symbionts appear to be completely isolated. Vicariance associated with orogeny of the Easter Microplate region, 2.5-5.3 million years ago, may have initiated isolation of the symbiont and host populations. Estimates of synonymous substitution rates for the protein-coding bacterial genes examined in this study were 0.77-1.62%/nucleotide/million years. CONCLUSIONS: Our present study reports the most comprehensive population genetic analyses of the chemosynthetic endosymbiotic bacteria based on high-throughput genetic data and extensive geographical sampling to date, and demonstrates the role of the geographical features, the Easter Microplate and geographical distance, in the intraspecific divergence of this bacterial species along the mid-ocean ridge axes in the eastern Pacific. Altogether, our results provide insights into extrinsic and intrinsic factors affecting the dispersal and evolution of chemosynthetic symbiotic partners in the hydrothermal vents along the eastern Pacific Ocean.

Niche specialization of bacteria in permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica.

Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, are chemically stratified with depth and have distinct biological gradients. Despite long-term research on these unique environments, data on the structure of the microbial communities in the water columns of these lakes are scarce. Here, we examined bacterial diversity in five ice-covered Antarctic lakes by 16S rRNA gene-based pyrosequencing. Distinct communities were present in each lake, reflecting the unique biogeochemical characteristics of these environments. Further, certain bacterial lineages were confined exclusively to specific depths within each lake. For example, candidate division WM88 occurred solely at a depth of 15 m in Lake Fryxell, whereas unknown lineages of Chlorobi were found only at a depth of 18 m in Lake Miers, and two distinct classes of Firmicutes inhabited East and West Lobe Bonney at depths of 30 m. Redundancy analysis revealed that community variation of bacterioplankton could be explained by the distinct conditions of each lake and depth; in particular, assemblages from layers beneath the chemocline had biogeochemical associations that differed from those in the upper layers. These patterns of community composition may represent bacterial adaptations to the extreme and unique biogeochemical gradients of ice-covered lakes in the McMurdo Dry Valleys.

Influence of Soil Characteristics and Proximity to Antarctic Research Stations on Abundance of Antibiotic Resistance Genes in Soils.

Soil is an important environmental reservoir of antibiotic resistance genes (ARGs), which are increasingly recognized as environmental contaminants. Methods to assess the risks associated with the acquisition or transfer of resistance mechanisms are still underdeveloped. Quantification of background levels of antibiotic resistance genes and what alters those is a first step in understanding our environmental resistome. Toward this goal, 62 samples were collected over 3 years from soils near the 30-year old Gondwana Research Station and for 4 years before and during development of the new Jang Bogo Research Station, both at Terra Nova Bay in Antarctica. These sites reflect limited and more extensive human impact, respectively. A qPCR array with 384 primer sets targeting antibiotic resistance genes and mobile genetic elements (MGEs) was used to detect and quantify these genes. A total of 73 ARGs and MGEs encompassing eight major antibiotic resistance gene categories were detected, but most at very low levels. Antarctic soil appeared to be a common reservoir for seven ARGs since they were present in most samples (42%-88%). If the seven widespread genes were removed, there was a correlation between the relative abundance of MGEs and ARGs, more typical of contaminated sites. There was a relationship between ARG content and distance from both research stations, with a significant effect at the Jang Bogo Station especially when excluding the seven widespread genes; however, the relative abundance of ARGs did not increase over the 4 year period. Silt, clay, total organic carbon, and SiO2 were the top edaphic factors that correlated with ARG abundance. Overall, this study identifies that human activity and certain soil characteristics correlate with antibiotic resistance genes in these oligotrophic Antarctic soils and provides a baseline of ARGs and MGEs for future comparisons.

Halocynthiibacter arcticus sp. nov., isolated from Arctic marine sediment.

A Gram-staining-negative, oxidase- and catalase-positive, non-motile, aerobic and rod-shaped bacterium producing white colonies, PAMC 20958T, was isolated from a marine sediment of the Arctic. PAMC 20958T grew at 10-27 °C (optimally at 21 °C), at pH 5.5-9.5 (optimally at pH 7.0-7.5) and in the presence of 0.5-7.5 % (w/v) (optimally at 2.0 %) NaCl. PAMC 20958T showed 97.5 % 16S rRNA gene sequence similarity with Halocynthiibacter namhaensis KCTC 32362T and formed a robust phylogenetic clade with this species. The average nucleotide identity value between strain PAMC 20958T and H. namhaensis KCTC 32362T was 79.7 % and the genome-to-genome distance was 13.0 % on average. The genomic DNA G+C content calculated from the genome sequence was 53.2 mol%. The major fatty acids were C18 : 1ω7c and/or C18 : 1ω6c. The major respiratory isoprenoid quinone was ubiquinone-10 (Q-10) and major polar lipids were phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid and two unidentified lipids. On the basis of phylogenetic analysis and genotypic and phenotypic data obtained in this study, it is concluded that strain PAMC 20958T ( = KCTC 42129T = JCM 30530T) represents the type strain of a novel species of the genus Halocynthiibacter, for which the name Halocynthiibacter arcticus sp. nov. is proposed.

Algibacter psychrophilus sp. nov., a psychrophilic bacterium isolated from marine sediment.

A Gram-stain-negative, aerobic, yellow-pigmented, flexirubin-negative, rod-shaped, non-motile and psychrophilic bacterial strain, PAMC 27237T, was isolated from marine sediment of the Ross Sea, Antarctica. Strain PAMC 27237T grew at 0-20 °C (optimally at 17 °C), at pH 5.0-9.5 (optimally at pH 7.0) and in the presence of 0-3.5 % (w/v) NaCl (optimally at 1.5-2.5 %). The major fatty acids (≥5 %) were iso-C17 : 0 3-OH, C17 : 0 2-OH, anteiso-C15 : 0, summed feature 3 (C16 : 1ω6c/C16 : 1ω7c), iso-C15 : 0 3-OH, anteiso-C17 : 1ω9c, anteiso-C15 : 1 A, iso-C16 : 0 3-OH and iso-C15 : 1 G. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids, four unidentified lipids and a glycolipid. The major respiratory quinone was MK-6. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain PAMC 27237T belongs to the genus Algibacter, showing high similarities with the type strains of Algibacter agarivorans (97.2 %), Algibacter agarilyticus (97.0 %) and Algibacter mikhailovii (96.4 %). Average nucleotide identity values between strain PAMC 27237T and the type strains of A. agarivorans and A. agarilyticuswere 83.1 and 84.2 %, respectively, and mean genome-to-genome distances were 22.4-24.2 %, indicating that strain PAMC 27237T is clearly distinguished from the most closely related species of the genus Algibacter. The genomic DNA G+C content calculated from genome sequences was 33.5 mol%. Based on the phenotypic, chemotaxonomic and phylogenetic data presented, strain PAMC 27237T is considered to represent a novel species of the genus Algibacter, for which the name Algibacter psychrophilus sp. nov. is proposed. The type strain is PAMC 27237T ( = KCTC 42130T = JCM 30370T).

Psychroserpens jangbogonensis sp. nov., a psychrophilic bacterium isolated from Antarctic marine sediment.

A Gram-staining-negative, yellow-pigmented, aerobic, rod-shaped and non-motile bacterium, PAMC 27130(T), was isolated from the marine sediment of the Ross Sea, Antarctica. The temperature, pH and NaCl tolerance ranges for growth were 4-20 °C, pH 6.0-9.0 and 0.5-5.0 % (w/v) NaCl, respectively. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain PAMC 27130(T) belonged to the genus Psychroserpens and was closely related to Psychroserpens mesophilus, Psychroserpens damuponensis and Psychroserpens burtonensis with 97.2, 94.7 and 94.2 % sequence similarities, respectively. Genomic relatedness analyses based on average nucleotide identity and genome-to-genome distance showed that strain PAMC 27130(T) could be clearly distinguished from other species of the genus Psychroserpens . The genomic DNA G+C content was 32.7 mol%. The major fatty acids (>10 %) were C20 : 4ω6c (13.2 %), iso-C15 : 0 (12.3 %), iso-C15 : 1 G (11.7 %) and iso-C15 : 0 3-OH (10.0 %). The major respiratory isoprenoid quinone was menaquinone-6 (MK-6) and the polar lipids were phosphatidylethanolamine, two unidentified aminolipids, an unidentified phospholipid, an unidentified aminophospholipid and three unidentified lipids. On the basis of genotypic and phenotypic data collected in this study, it is proposed that strain PAMC 27130(T) represents a novel species of the genus Psychroserpens, for which the name Psychroserpens jangbogonensis sp. nov. is proposed. The type strain is PAMC 27130(T) ( = KCTC 42128(T) = JCM 30228(T)).

Algal and fungal diversity in Antarctic lichens.

The composition of lichen ecosystems except mycobiont and photobiont has not been evaluated intensively. In addition, recent studies to identify algal genotypes have raised questions about the specific relationship between mycobiont and photobiont. In the current study, we analyzed algal and fungal community structures in lichen species from King George Island, Antarctica, by pyrosequencing of eukaryotic large subunit (LSU) and algal internal transcribed spacer (ITS) domains of the nuclear rRNA gene. The sequencing results of LSU and ITS regions indicated that each lichen thallus contained diverse algal species. The major algal operational taxonomic unit (OTU) defined at a 99% similarity cutoff of LSU sequences accounted for 78.7-100% of the total algal community in each sample. In several cases, the major OTUs defined by LSU sequences were represented by two closely related OTUs defined by 98% sequence similarity of ITS domain. The results of LSU sequences indicated that lichen-associated fungi belonged to the Arthoniomycetes, Eurotiomycetes, Lecanoromycetes, Leotiomycetes, and Sordariomycetes of the Ascomycota, and Tremellomycetes and Cystobasidiomycetes of the Basidiomycota. The composition of major photobiont species and lichen-associated fungal community were mostly related to the mycobiont species. The contribution of growth forms or substrates on composition of photobiont and lichen-associated fungi was not evident.

Anthranilate degradation by a cold-adapted Pseudomonas sp.

An alpine soil bacterium Pseudomonas sp. strain PAMC 25931 was characterized as eurypsychrophilic (both psychrophilic and mesotolerant) with a broad temperature range of 5-30 °C both for anthranilate (2-aminobenzoate) degradation and concomitant cell growth. Two degradative gene clusters (antABC and catBCA) were detected from a fosmid clone in the PAMC 25931 genomic library; each cluster was confirmed to be specifically induced by anthranilate. When expressed in Escherichia coli, the recombinant AntABC (anthranilate 1,2-dioxygenase, AntDO) converted anthranilate into catechol, exhibiting strict specificity toward anthranilate. Recombinant CatA (catechol 1,2-dioxygenase, C12O) from the organism was active over a broad temperature range (5-37 °C). However, CatA rapidly lost the enzyme activity when incubated at above 25 °C. For example, 1 h-preincubation at 37 °C resulted in 100% loss of enzyme activity, while a counterpart from mesophilic Pseudomonas putida mt-2 did not show any negative effect on the initial enzyme activity. These results suggest that CatA is a new cold-adapted thermolabile enzyme, which might be a product through the adaptation process of PAMC 25931 to naturally cold environments and contribute to its ability to grow on anthranilate there.

Effect of temperature on biofilm formation by Antarctic marine bacteria in a microfluidic device.

Polar biofilms have become an increasingly popular biological issue because new materials and phenotypes have been discovered in microorganisms in the polar region. Various environmental factors affect the functionality and adaptation of microorganisms. Because the polar region represents an extremely cold environment, polar microorganisms have a functionality different from that of normal microorganisms. Thus, determining the effective temperature for the development of polar biofilms is crucial. Here, we present a simple, novel one-pot assay for analysis of the effect of temperature on formation of Antarctic bacterial biofilm using a microfluidic system where continuous temperature gradients are generated. We find that a specific range of temperature is required for the growth of biofilms. Thus, this microfluidic approach provides precise information regarding the effective temperature for polar biofilm development with a new high-throughput screening format.

Lacinutrix jangbogonensis sp. nov., a psychrophilic bacterium isolated from Antarctic marine sediment and emended description of the genus Lacinutrix.

A Gram-negative, strictly aerobic, non-motile, rod-shaped and psychrophilic bacterial strain, PAMC 27137(T), was isolated from the marine sediment of the Ross Sea, Antarctica. Strain PAMC 27137(T) was observed to grow at 4-10 °C, at pH 6.5-7.5 and in the presence of 2.5-4.0 % (w/v) sea salts. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain PAMC 27137(T) belongs to the genus Lacinutrix showing the high similarities with Lacinutrix mariniflava JCM 13824(T) (97.6 %) and Lacinutrix algicola JCM 13825(T) (97.1 %). Genomic relatedness analyses based on the average nucleotide identity and the genome-to-genome distance showed that strain PAMC 27137(T) is clearly distinguished from the most closely related Lacinutrix species. The major fatty acids (>5 %) were identified as iso-C15:1 G (19.9 %), iso-C15:0 (19.3 %), iso-C17:0 3-OH (11.3 %), summed feature 9 (C16:0 10-methyl and/or iso-C17:1 ω9c as defined by MIDI, 9.1 %), iso-C15:0 3-OH (7.5 %), and anteiso-C15:1 A (5.8 %). The polar lipids were found to consist of phosphatidylethanolamine, an unidentified aminolipid, an unidentified aminophospholipid, and five unidentified phospholipids. The major respiratory quinone was identified as MK-6. The genomic DNA G+C content was determined to be 32.1 mol%. Based on the data from this polyphasic taxonomic study, strain PAMC 27137(T) is considered to represent a novel species of the genus Lacinutrix, for which the name Lacinutrix jangbogonensis sp. nov. is proposed. The type strain is PAMC 27137(T) (=KCTC 32573(T)=JCM 19883(T)).

Biodiversity and physiological characteristics of Antarctic and Arctic lichens-associated bacteria.

The diversity and physiological characteristics of culturable bacteria associated with lichens from different habitats of the Arctic and Antarctica were investigated. The 68 retrieved isolates could be grouped on the basis of their 16S rRNA gene sequences into 26 phylotypes affiliated with the phyla Actinobacteria, Bacteroidetes, Deinococcus-Thermus, and Firmicutes and with the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. Isolates belonging to the Alphaproteobacteria were the most abundant, followed by those belonging to Actinobacteria, Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, and Deinococcus-Thermus. Phylogenetic analysis showed that approximately 21 % of the total isolates represented a potentially novel species or genus (≤97 % sequence similarity). Strains belonging to the genera Sphingomonas, Frondihabitans, Hymenobacter, and Burkholderia were recovered from lichen samples from both geographic locations, implying common and important bacterial functions within lichens. Extracellular protease activities were detected in six isolates, affiliated with Burkholderia, Frondihabitans, Hymenobacter, Pseudomonas, and Rhodanobacter. Extracellular lipase activities were detected in 37 isolates of the genera Burkholderia, Deinococcus, Frondihabitans, Pseudomonas, Rhodanobacter, Sphingomonas, and Subtercola. This is the first report on the culturable bacterial diversity present within lichens from Arctic and Antarctica and the isolates described herein are valuable resources to decode the functional and ecological roles of bacteria within lichens. In addition, the low similarity (≤97 %) of the recovered isolates to known species and their production of cold-active enzymes together suggest that lichens are noteworthy sources of novel bacterial strains for use in biotechnological applications.

Polaribacter sejongensis sp. nov., isolated from Antarctic soil, and emended descriptions of the genus Polaribacter, Polaribacter butkevichii and Polaribacter irgensii.

A Gram-staining-negative, catalase- and oxidase-positive, non-motile bacterium, designated strain KOPRI 21160(T), was isolated from Antarctic soil. Based on 16S rRNA gene sequence analysis, strain KOPRI 21160(T) was found to belong to the genus Polaribacter. Sequence similarity between strain KOPRI 21160(T) and the type strains of species of the genus Polaribacter was 94.2-98.3 %. The nearest phylogenetic neighbours of strain KOPRI 21160(T) were Polaribacter butkevichii KCTC 12100(T) (98.3 % similarity) and Polaribacter irgensii KCTC 23136(T) (97.5 %). DNA-DNA relatedness was 50.6 %, between strain KOPRI 21160(T) and P. butkevichii KCTC 12100(T), and 45.2 % between strain KOPRI 21160(T) and P. irgensii KCTC 23136(T). Strain KOPRI 21160(T) grew at 4-37 °C and at pH 7.0-8.5. It could hydrolyse DNA, starch and Tweens 20, 40, 60 and 80. Menaquinone-6 (MK-6) was the only respiratory quinone, and iso-C15 : 0, iso-C15 : 0 3-OH and C15 : 1ω6c were the major cellular fatty acids. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and one unidentified lipid. The DNA G+C content was 30.0 mol%. Based on data from our polyphasic study, the organism is considered to represent a novel species of the genus Polaribacter, for which we propose the name Polaribacter sejongensis sp. nov. The type strain is KOPRI 21160(T) ( = KCTC 23670(T) = JCM 18092(T)). Emended descriptions of the genus Polaribacter, Polaribacter butkevichii Nedashkovskaya et al. 2005 and Polaribacter irgensii Gosink et al. 1998 are also proposed.

The Revision of Lichen Flora Around Maxwell Bay, King George Island, Maritime Antarctic.

Since the floristic study of lichens at the Barton and Weaver Peninsulas of King George Island in 2006, there have been intense investigations of the lichen flora of the two peninsulas as well as that of Fildes Peninsula and Ardley Island in Maxwell Bay, King George Island, South Shetland Islands, maritime Antarctic. In this study, a total of 104 species belonging to 53 genera, are identified from investigations of lichens that were collected in austral summer seasons from 2008 to 2016. Phenotypic and molecular analyses were incorporated for taxonomic identification. In particular, 31 species are found to be endemic to the Antarctic and 22 species are newly recorded to the Maxwell Bay region. Lepra dactylina, Stereocaulon caespitosum, and Wahlenbergiella striatula are newly recorded in the Antarctic, and the previously reported taxon Cladonia furcata is excluded from the formerly recorded list due to misidentification. We also provide ecological and geographical information about lichen associations and habitat preferences.

Genome sequence of Pseudomonas sp. strain PAMC 25886, isolated from alpine glacial cryoconite.

Pseudomonas spp. have shown characteristics of efficiently metabolizing environmental pollutants and also producing exopolysaccharides known as biofilms. Here we present the draft genome sequence of Pseudomonas sp. strain PAMC 25886, which was isolated from glacier cryoconite in the Alps mountain permafrost region and which may provide further insight into biodegradative and/or biofilm-producing mechanisms in a cold environment.