The OsICS1 is directly regulated by OsWRKY6 and increases resistance against Xanthomonas oryzae pv. oryzae.

KEY MESSAGE: OsICS1 but not OsICS1-L mediates the rice response to Xoo inoculation, with its overexpression increasing resistance against this pathogen. OsICS1 but not OsICS-L is directly upregulated by OsWRKY6. Rice (Oryza sativa) is a staple crop for about half of the global population and is particularly important in the diets of people living in Asia, Latin America, and Africa. This crop is continually threatened by bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo), which drastically reduces yields; therefore, it is needed to elucidate the plant's resistance mechanisms against Xoo. Isochorismate synthase (ICS1) generates salicylic acid (SA) and increases resistance against bacterial disease. The OsICS1 is differently annotated in rice genome databases and has not yet been functionally characterized in the context of Xoo infection. Here, we report that the expression of the OsICS1 is directly regulated by OsWRKY6 and increases plant resistance against Xoo. Inoculation with Xoo increased the expression of OsICS1 but not that of the long variant of OsICS1 (OsICS1-L). OsWRKY6 directly activated the OsICS1 promoter but not the OsICS1-L promoter. OsICS1 overexpression in rice increased resistance against Xoo through the induction of SA-dependent bacterial defense genes. These data show that OsICS1 promotes resistance against Xoo infection.

Granulicatella seriolae sp. nov., a Novel Facultative Anaerobe Isolated from Yellowtail Marine Fish.

A bacterial strain, designated as S8T, was isolated from the gut contents of Seriola quinqueradiata from the coastal sea area of Jeju Island, South Korea. The strain is a Gram-staining positive, non-motile, non-spore-forming, facultative anaerobic coccus. Optimal growth was observed at 30 °C, pH 8.0-9.0, and 0-0.5% w/v NaCl, under anaerobic conditions. The predominant fatty acids were C18:1 ω9c, C16:0, C18:0, and C16:1 ω9c, while quinone was not detected. The genome was 2,224,566 bp long, with a GC content of 38.2%. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain S8T had 96.2% similarity with Granulicatella adiacens ATCC 49175T, its closest known species according to nomenclature. The DNA-DNA hybridization (dDDH), average nucleotide identity, and average amino acid identity values between strain S8T and G. adiacens ATCC 49175T were 25.7%, 85.5%, and 77.2%, respectively, all of which fall below the recommended threshold for species differentiation. Based on genomic, phenotypic, and phylogenetic evidence, we propose that strain S8T should be a novel species within the genus Granulicatella, for with the name Granulicatella seriolae sp. nov. is proposed. The type strain is S8T (KCTC 43438T = JCM 35604T).

Plant growth-promoting archaea trigger induced systemic resistance in Arabidopsis thaliana against Pectobacterium carotovorum and Pseudomonas syringae.

Archaea have inhabited the earth for a long period of time and are ubiquitously distributed in diverse environments. However, few studies have focused on the interactions of archaea with other organisms, including eukaryotes such as plants, since it is difficult to cultivate sufficient numbers of archaeal cells for analysis. In this study, we investigated the interaction between soil archaea and Arabidopsis thaliana. We demonstrate for the first time that soil archaea promote plant growth and trigger induced systemic resistance (ISR) against the necrotrophic bacterium Pectobacterium carotovorum subsp. carotovorum SCC1 and biotrophic bacterium Pseudomonas syringae pv. tomato DC3000. Ammonia-oxidizing archaeon Nitrosocosmicus oleophilus MY3 cells clearly colonized the root surface of Arabidopsis plants, and increased resistance against both pathogenic species via the salicylic acid-independent signalling pathway. This mechanism of bacterial resistance resembles that underlying soil bacteria- and fungi-mediated ISR signalling. Additionally, volatile emissions from N. oleophilus MY3 were identified as major archaeal determinants that elicit ISR. Our results lay a foundation for archaea-plant interactions as a new field of research.

Hydrogen peroxide detoxification is a key mechanism for growth of ammonia-oxidizing archaea.

Ammonia-oxidizing archaea (AOA), that is, members of the Thaumarchaeota phylum, occur ubiquitously in the environment and are of major significance for global nitrogen cycling. However, controls on cell growth and organic carbon assimilation by AOA are poorly understood. We isolated an ammonia-oxidizing archaeon (designated strain DDS1) from seawater and used this organism to study the physiology of ammonia oxidation. These findings were confirmed using four additional Thaumarchaeota strains from both marine and terrestrial habitats. Ammonia oxidation by strain DDS1 was enhanced in coculture with other bacteria, as well as in artificial seawater media supplemented with α-keto acids (e.g., pyruvate, oxaloacetate). α-Keto acid-enhanced activity of AOA has previously been interpreted as evidence of mixotrophy. However, assays for heterotrophic growth indicated that incorporation of pyruvate into archaeal membrane lipids was negligible. Lipid carbon atoms were, instead, derived from dissolved inorganic carbon, indicating strict autotrophic growth. α-Keto acids spontaneously detoxify H2O2 via a nonenzymatic decarboxylation reaction, suggesting a role of α-keto acids as H2O2 scavengers. Indeed, agents that also scavenge H2O2, such as dimethylthiourea and catalase, replaced the α-keto acid requirement, enhancing growth of strain DDS1. In fact, in the absence of α-keto acids, strain DDS1 and other AOA isolates were shown to endogenously produce H2O2 (up to ∼4.5 µM), which was inhibitory to growth. Genomic analyses indicated catalase genes are largely absent in the AOA. Our results indicate that AOA broadly feature strict autotrophic nutrition and implicate H2O2 as an important factor determining the activity, evolution, and community ecology of AOA ecotypes.

Nitrosarchaeum koreense gen. nov., sp. nov., an aerobic and mesophilic, ammonia-oxidizing archaeon member of the phylum Thaumarchaeota isolated from agricultural soil.

A mesophilic, chemolithoautotrophic, neutrophilic and aerobic ammonia-oxidizing archaeon, designated strain MY1T, was isolated from agricultural soil. Microscopic observation revealed short, rod-shaped cells with a diameter of 0.3-0.5 µm and length of 0.6-1.0 µm. The isolate had no flagella and pili, and possessed no genes associated with archaeal flagella synthesis. The major membrane lipids consisted mainly of the glycerol dibiphytanyl glycerol tetraether (GDGT) lipids GDGT-0 to GDGT-4 and crenarchaeol. The major intact polar lipids (IPLs) were determined as hexose plus phosphohexose IPL and dihexose IPL. Strain MY1T obtains energy by aerobically oxidizing ammonia and carbon by fixing CO2. An optimal growth was observed at 25 °C, at pH 7 and with 0.2-0.4 % (w/v) salinity that corresponds with its terrestrial habitat. The addition of α-keto acids was necessary to stimulate growth. The strain tolerated ammonium and nitrite concentrations up to 10 and 5 mM, respectively. The MY1T genome has a DNA G+C content of 32.7 mol%. Phylogenetic analysis based on the 16S rRNA gene showed that strain MY1T belongs to the family Nitrosopumilaceaeof the phylum Thaumarchaeota, sharing the highest 16S rRNA gene sequence similarity (96.6-97.1 %) with marine isolates of the genus Nitrosopumilus. The average nucleotide identity was 78 % between strain MY1T and Nitrosopumilus maritimus SCM1T, indicating distant relatedness. Based on the phenotypic, phylogenetic and genomic analyses, it was concluded that strain MY1T belongs to the novel genus Nitrosarchaeum, under which the name Nitrosarchaeum koreense sp. nov. is proposed as the type species. The type strain is MY1T (=JCM 31640T=KCTC 4249T).

Ketobacter alkanivorans gen. nov., sp. nov., an n-alkane-degrading bacterium isolated from seawater.

Strain GI5T was isolated from a surface seawater sample collected from Garorim Bay (West Sea, Republic of Korea). The isolated strain was aerobic, Gram-stain-negative, rod-shaped, motile by means of a polar flagellum, negative for catalase and weakly positive for oxidase. The optimum growth pH, salinity and temperature were determined to be pH 7.5-8.0, 3 % NaCl (w/v) and 25 °C, respectively; the growth ranges were pH 6.0-9.0, 1-7 % NaCl (w/v) and 18-40 °C. The results of phylogenetic analysis of 16S rRNA gene sequences indicated that GI5T clustered within the family Alcanivoracaceae, and most closely with Alcanivorax dieseloleiB-5T and Alcanivorax marinusR8-12T (91.9 % and 91.6 % similarity, respectively). The major cellular fatty acids in GI5T were C18 : 1ω7c/C18 : 1ω6c (44.45 %), C16 : 1ω6c/C16 : 1ω7c (14.17 %) and C16 : 0 (10.19 %); this profile was distinct from those of the closely related species. The major respiratory quinone of GI5T was Q-8. The main polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Two putative alkane hydroxylase (alkB) genes were identified in GI5T. The G+C content of the genomic DNA of GI5T was determined to be 51.2 mol%. On the basis of the results of phenotypic, chemotaxonomic and phylogenetic studies, strain GI5T represents a novel species of a novel genus of the family Alcanivoracaceae, for which we propose the name Ketobacter alkanivorans gen. nov., sp. nov.; the type strain is GI5T (=KCTC 52659T=JCM 31835T).

Ammonia-oxidising archaea living at low pH: Insights from comparative genomics.

Obligate acidophilic members of the thaumarchaeotal genus Candidatus Nitrosotalea play an important role in nitrification in acidic soils, but their evolutionary and physiological adaptations to acidic environments are still poorly understood, with only a single member of this genus (Ca. N. devanaterra) having its genome sequenced. In this study, we sequenced the genomes of two additional cultured Ca. Nitrosotalea strains, extracted an almost complete Ca. Nitrosotalea metagenome-assembled genome from an acidic fen, and performed comparative genomics of the four Ca. Nitrosotalea genomes with 19 other archaeal ammonia oxidiser genomes. Average nucleotide and amino acid identities revealed that the four Ca. Nitrosotalea strains represent separate species within the genus. The four Ca. Nitrosotalea genomes contained a core set of 103 orthologous gene families absent from all other ammonia-oxidizing archaea and, for most of these gene families, expression could be demonstrated in laboratory culture or the environment via proteomic or metatranscriptomic analyses respectively. Phylogenetic analyses indicated that four of these core gene families were acquired by the Ca. Nitrosotalea common ancestor via horizontal gene transfer from acidophilic representatives of Euryarchaeota. We hypothesize that gene exchange with these acidophiles contributed to the competitive success of the Ca. Nitrosotalea lineage in acidic environments.

Kiloniella antarctica sp. nov., isolated from a polynya of Amundsen Sea in Western Antarctic Sea.

A taxonomic study was conducted on strain soj2014T, which was isolated from the surface water of a polynya in the Antarctic Sea. Comparative 16S rRNA gene sequence analysis showed that strain soj2014T belongs to the family Kiloniellaceae and is closely related to Kiloniella spongiae MEBiC09566T, 'Kiloniella litopenaei' P1-1T and Kiloniella laminariae LD81T (98.0 %, 97.8 % and 96.2 % 16S rRNA gene sequence similarity, respectively). The DNA-DNA hybridization values between strain soj2014T and closely related strains were below 28.6 %. The G+C content of the genomic DNA of strain soj2014T was 45.5 mol%. The predominant cellular fatty acids were summed feature 8 (composed of C18 : 1ω6c/C18 : 1ω7c, 57.0 %) and summed feature 3 (composed of C16 : 1ω6c/C16 : 1ω7c, 23.5 %). Strain soj2014T was Gram-stain-negative, slightly curved, spiral-shaped, and motile with a single polar flagellum. The strain grew at 0-30 °C (optimum, 25 °C), in 1.5-5.1 % (w/v) NaCl (optimum, 2.1-2.4 %) and at pH 5.5-9.5 (optimum, 7.5-8.0). It also had differential carbohydrate utilization traits and enzyme activities compared with closely related strains. Based on these phylogenetic, phenotypic and chemotaxonomic analyses, strain soj2014T represents a distinct species, separable from the reference strains, and is, therefore, proposed as a novel species, Kiloniella antarctica sp. nov. The type strain is soj2014T (=KCTC 42186T=JCM 30386T).

Leeuwenhoekiella polynyae sp. nov., isolated from a polynya in western Antarctica.

A Gram-stain-negative, motile by gliding, rod-shaped bacterial strain, designated SOJ2014-1(T) was isolated from surface water of a polynya in the Antarctic Ocean. A comparative 16S rRNA gene sequence analysis showed that strain SOJ2014-1(T) belongs to the genus Leeuwenhoekiella and is most closely related to Leeuwenhoekiella marinoflava DSM 3653(T) (97.5% 16S rRNA gene sequence similarity). The G+C content of the genomic DNA of strain SOJ2014-1(T) was 38.8 mol%. Its predominant cellular fatty acids were summed feature 3 (composed of C16 : 1ω6c and/or C16 : 1ω7c), iso-C17 : 0 3-OH, iso-C15 : 0, iso-C15 : 1 G and summed feature 9 (composed of iso-C17 : 1ω9c and/or 10-methyl C16 : 0). DNA-DNA relatedness between strain SOJ2014-1(T) and close relatives, L. marinoflava DSM 3653(T) and Leeuwenhoekiella aequorea LMG 22550(T), was below 49%. The respiratory quinone was MK-6. The major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and two unidentified lipids. The strain grew at 0-35 °C (optimum, 25 °C) with 0-14.0% (w/v) NaCl (optimum, 1.0-5.0%). It was strictly aerobic and had different carbohydrate utilization traits compared with L. marinoflava DSM 3653(T). Based on the phenotypic, chemotaxonomic and phylogenetic analyses, strain SOJ2014-1(T) is proposed as a representative of a novel species, Leeuwenhoekiella polynyae. The type strain is SOJ2014-1(T) ( =KCTC 42185(T) =JCM 30387(T)).

Geosporobacter ferrireducens sp. nov., an anaerobic iron-reducing bacterium isolated from an oil-contaminated site.

In this study, an alkaliphilic and heterotrophic iron-reducing bacterial strain, IRF9(T), was isolated from an oil-contaminated soil in the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain IRF9(T) belongs to the genus Geosporobacter in the family Clostridiaceae and is most closely related to Geosporobacter subterraneus VNs68(T) (96.9 % sequence similarity). Cells of strain IRF9(T) were observed to be straight or curved rod-shaped, motile and Gram-negative. Optimal growth of strain IRF9(T) was observed at pH 9.0-9.5 and 40 °C. The strain was found to grow within pH and temperature ranges of 6.5-10.0 and 25-45 °C, respectively. NaCl was not required for growth. Fe(III), but not sulfate, thiosulfate or elemental sulfur can be used by strain IRF9(T) as an electron acceptor. A limited number of carbohydrates and amino acids, including D-glucose, D-fructose, D-mannitol, D-ribose and L-arginine, support growth of strain IRF9(T). The main fatty acids (>10 %) of strain IRF9(T) were identified as C14:0 (18.4 %), C16:1 cis9 (13.6 %), C16:0 (12.4 %) and C16:0 dimethyl acetal (17.7 %). Major respiratory quinone was identified as menaquinone MK-5 (V-H2). The main polar lipids were found to be phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The DNA G+C content of strain IRF9(T) was determined to be 37.2 mol%, which is lower than that of G. subterraneus VNs68(T) (42.2 mol%). Based on phenotypic, chemotaxonomic, and phylogenetic studies, we conclude that strain IRF9(T) (=JCM 19987(T) = KCTC 15395(T)) represents a new species of the genus Geosporobacter, for which we propose the name Geosporobacter ferrireducens sp. nov.

Draconibacterium filum sp. nov., a new species of the genus of Draconibacterium from sediment of the east coast of the Korean Peninsula.

A Gram-stain negative, long rod shaped, facultatively anaerobic bacterium, designated strain F2(T), was isolated from coastal sediment of the Korean Peninsula. Strain F2(T) was found to grow at 10-40 °C (optimum 30 °C), at pH 6.0-8.5 (optimum pH 7.5) and at 0.0-8.0 % (w/v) NaCl (optimum 3.0 %). Phylogenetic analysis of the 16S rRNA gene sequence showed that strain F2(T) is closely related to Draconibacterium orientale FH5(T) (with 97.9 % 16S rRNA gene similarity) of the family Prolixibacteraceae of the phylum Bacteroidetes. The major isoprenoid quinone was identified as MK-7 and the main fatty acids as iso-C15:0 (24.1 %), anteiso-C15:0 (15.4 %), C16:0 (10.7 %), iso-C17:0 3-OH (7.6 %) and iso-C16:0 3-OH (5.9 %). The major polar lipids were identified as phosphatidylethanolamine, phosphatidylinositol and four unidentified polar lipids. The genomic DNA G+C content of strain F2(T) was determined to be 44.7 mol% and the DNA-DNA relatedness of strain F2(T) with D. orientale DSM 25947(T) was 34.6 ± 4.3 %. Nitrate reduction capability and cell morphology of strain F2(T) are distinct from those of the closest relative, D. orientale DSM 25947(T). Based on these properties, we propose strain F2(T) represents a novel species within the genus Draconibacterium, with the name Draconibacterium filum sp. nov. The type strain of D. filum is F2(T) (=KCTC 32486(T) = JCM 19986(T)).

Unveiling abundance and distribution of planktonic Bacteria and Archaea in a polynya in Amundsen Sea, Antarctica.

Polynyas, areas of open water surrounded by sea ice, are sites of intense primary production and ecological hotspots in the Antarctic Ocean. This study determined the spatial variation in communities of prokaryotes in a polynya in the Amundsen Sea using 454 pyrosequencing technology, and the results were compared with biotic and abiotic environmental factors. The bacterial abundance was correlated with that of phytoplankton, Phaeocystis spp. and diatoms. A cluster analysis indicated that the bacterial communities in the surface waters of the polynya were distinct from those under the sea ice. Overall, two bacterial clades, Polaribacter (20-64%) and uncultivated Oceanospirillaceae (7-34%), dominated the surface water in the polynya while the Pelagibacter clade was abundant at all depths (7-42%). The archaeal communities were not as diverse as the bacterial communities in the polynya, and marine group I was dominant (> 80%). Canonical correspondence analysis indicated that the oceanographic properties facilitated the development of distinct prokaryotic assemblages in the polynya. This analysis of the diversity and composition of the psychrophilic prokaryotes associated with high phytoplankton production provides new insights into the roles of prokaryotes in biogeochemical cycles in high-latitude polynyas.

An uncultivated nitrate-reducing member of the genus Herminiimonas degrades toluene.

Stable isotope probing (SIP) is a cultivation-free methodology that provides information about the identity of microorganisms participating in assimilatory processes in complex communities. In this study, a Herminiimonas-related bacterium was identified as the dominant member of a denitrifying microcosm fed [(13)C]toluene. The genome of the uncultivated toluene-degrading bacterium was obtained by applying pyrosequencing to the heavy DNA fraction. The draft genome comprised ~3.8 Mb, in 131 assembled contigs. Metabolic reconstruction of aromatic hydrocarbon (toluene, benzoate, p-cresol, 4-hydroxybenzoate, phenylacetate, and cyclohexane carboxylate) degradation indicated that the bacterium might specialize in anaerobic hydrocarbon degradation. This characteristic is novel for the order Burkholderiales within the class Betaproteobacteria. Under aerobic conditions, the benzoate oxidation gene cluster (BOX) system is likely involved in the degradation of benzoate via benzoyl coenzyme A. Many putative genes for aromatic hydrocarbon degradation were closely related to those in the Rhodocyclaceae (particularly Aromatoleum aromaticum EbN1) with respect to organization and sequence similarity. Putative mobile genetic elements associated with these catabolic genes were highly abundant, suggesting gene acquisition by Herminiimonas via horizontal gene transfer.

A mesophilic, autotrophic, ammonia-oxidizing archaeon of thaumarchaeal group I.1a cultivated from a deep oligotrophic soil horizon.

Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e., Nitrosopumilus maritimus and "Candidatus Nitrosoarchaeum koreensis," is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of N. maritimus and "Ca. Nitrosoarchaeum koreensis," and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name "Candidatus Nitrosotenuis chungbukensis" for the ammonia-oxidizing archaeal strain MY2.

Nitrous oxide respiration in acidophilic methanotrophs.

Aerobic methanotrophic bacteria are considered strict aerobes but are often highly abundant in hypoxic and even anoxic environments. Despite possessing denitrification genes, it remains to be verified whether denitrification contributes to their growth. Here, we show that acidophilic methanotrophs can respire nitrous oxide (N2O) and grow anaerobically on diverse non-methane substrates, including methanol, C-C substrates, and hydrogen. We study two strains that possess N2O reductase genes: Methylocella tundrae T4 and Methylacidiphilum caldifontis IT6. We show that N2O respiration supports growth of Methylacidiphilum caldifontis at an extremely acidic pH of 2.0, exceeding the known physiological pH limits for microbial N2O consumption. Methylocella tundrae simultaneously consumes N2O and CH4 in suboxic conditions, indicating robustness of its N2O reductase activity in the presence of O2. Furthermore, in O2-limiting conditions, the amount of CH4 oxidized per O2 reduced increases when N2O is added, indicating that Methylocella tundrae can direct more O2 towards methane monooxygenase. Thus, our results demonstrate that some methanotrophs can respire N2O independently or simultaneously with O2, which may facilitate their growth and survival in dynamic environments. Such metabolic capability enables these bacteria to simultaneously reduce the release of the key greenhouse gases CO2, CH4, and N2O.

Adaptive traits of Nitrosocosmicus clade ammonia-oxidizing archaea.

Nitrification is a core process in the global nitrogen (N) cycle mediated by ammonia-oxidizing microorganisms, including ammonia-oxidizing archaea (AOA) as a key player. Although much is known about AOA abundance and diversity across environments, the genetic drivers of the ecophysiological adaptations of the AOA are often less clearly defined. This is especially true for AOA within the genus Nitrosocosmicus, which have several unique physiological traits (e.g., high substrate tolerance, low substrate affinity, and large cell size). To better understand what separates the physiology of Nitrosocosmicus AOA, we performed comparative genomics with genomes from 39 cultured AOA, including five Nitrosocosmicus AOA. The absence of a canonical high-affinity type ammonium transporter and typical S-layer structural genes was found to be conserved across all Nitrosocosmicus AOA. In agreement, cryo-electron tomography confirmed the absence of a visible outermost S-layer structure, which has been observed in other AOA. In contrast to other AOA, the cryo-electron tomography highlighted the possibility that Nitrosocosmicus AOA may possess a glycoprotein or glycolipid-based glycocalyx cell covering outer layer. Together, the genomic, physiological, and metabolic properties revealed in this study provide insight into niche adaptation mechanisms and the overall ecophysiology of members of the Nitrosocosmicus clade in various terrestrial ecosystems. IMPORTANCE: Nitrification is a vital process within the global biogeochemical nitrogen cycle but plays a significant role in the eutrophication of aquatic ecosystems and the production of the greenhouse gas nitrous oxide (N2O) from industrial agriculture ecosystems. While various types of ammonia-oxidizing microorganisms play a critical role in the N cycle, ammonia-oxidizing archaea (AOA) are often the most abundant nitrifiers in natural environments. Members of the genus Nitrosocosmicus are one of the prevalent AOA groups detected in undisturbed terrestrial ecosystems and have previously been reported to possess a range of physiological characteristics that set their physiology apart from other AOA species. This study provides significant progress in understanding these unique physiological traits and their genetic drivers. Our results highlight how physiological studies based on comparative genomics-driven hypotheses can contribute to understanding the unique niche of Nitrosocosmicus AOA.

Marinoscillum luteum sp. nov., isolated from marine sediment.

A novel strain, designated SJP7(T), was isolated from sediment of the Tofua Arc of the Tonga Trench. The 16S rRNA gene sequence of the isolate showed the highest similarity to that of Marinoscillum pacificum KCCM 42325(T) (95.9%). Phylogenetic analysis revealed that the isolate formed a distinct phyletic line with Marinoscillum pacificum KCCM 42325(T) and Marinoscillum furvescens LMG 13023(T) within the family Cytophagaceae. Cells of strain SJP7(T) were Gram-stain-negative and appeared as long rods that were motile by gliding. Growth was observed at 15-40 °C (optimum, 30 °C), at pH 5.5-9.0 (optimum, pH 7.5-8.0) and in the presence of 0.5-7.0% (w/v) NaCl (optimum, 2.5-3%). The major respiratory quinone was MK-7. The dominant fatty acids were summed feature 3 (comprising C(16:1)ω7c and/or C(16:1)ω6c), iso-C(15:0) and C(16:1)ω5c. The DNA G+C content was 43.5 mol%. These properties support the affiliation of strain SJP7(T) with the genus Marinoscillum. Further phenotypic differentiation of strain SJP7(T) from other species of the genus Marinoscillum was indicated by the results of physiological and biochemical tests. On the basis of evidence from our polyphasic taxonomic study, strain SJP7(T) represents a novel species of the genus Marinoscillum, for which the name Marinoscillum luteum sp. nov. is proposed. The type strain of Marinoscillum luteum is SJP7(T) ( =KCTC 23939(T) =NCAIM B02491(T)).

Natronomonas gomsonensis sp. nov., isolated from a solar saltern.

A halophilic archaeal strain, SA3(T), was isolated from sediment of a solar saltern in Gomso Bay, Republic of Korea. Cells of strain SA3(T) were observed to be coccoid-shaped, to lyse in distilled water, Gram stain-negative and to form red-pigmented colonies. Strain SA3(T) was found to require at least 18 % (w/v) NaCl for growth. Optimal growth was observed at 24 % (w/v) NaCl and 6 % (w/v) MgCl2. The optimum pH and temperature for growth were determined to be pH 7.0 and 40 °C, respectively, while the strain was found to grow within pH and temperature ranges of 5.5-8.0 and 20-45 °C, respectively. The polar lipids were determined to consist of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, unidentified phosphoglycolipids and unidentified phospholipids. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SA3(T) was most closely related to the members of the genus Natronomonas, Natronomonas moolapensis JCM 14361(T) (95.2 %) and Natronomonas pharaonis JCM 8858(T) (95.1 %). The genomic DNA G+C content (61.8 mol%) determined for strain SA3(T) was slightly lower than those of N. moolapensis JCM 14361(T) (63.4 mol%) and N. pharaonis JCM 8858(T) (64.3 mol%). DNA-DNA hybridization values between N. moolapensis JCM 14361(T) and N. pharaonis JCM 8858(T) and strain SA3(T) were <20 %. Based on phenotypic, chemotaxonomic and phylogenetic properties, we describe a new species of the genus Natronomonas, represented by strain SA3(T) (=JCM 17867(T) = KCTC 4088(T)), for which we propose the name Natronomonas gomsonensis sp. nov.

Hoeflea halophila sp. nov., a novel bacterium isolated from marine sediment of the East Sea, Korea.

A Gram-negative, aerobic, motile, straight or curved rod-shaped marine bacterium was isolated from marine sediment of the East Sea, Korea. The isolated strain, JG120-1(T), grows with 0-5 % (w/v) NaCl and at 15-30 °C and pH 6-9. α-galactosidase activity test was positive. Comparative 16S rRNA gene sequence studies showed that this strain belonged to the Alphaproteobacteria and was the most closely related to Hoeflea alexandrii AM1 V30(T), Hoeflea phototrophica DFL-43(T) and Hoeflea marina LMG 128(T) (98.9, 97.9 and 97.0 % 16S rRNA gene sequence similarities, respectively). Strain JG120-1(T) was found to possess summed feature 8 (C18:1ω7c/C18:1ω6c, 71.11 %) as the major cellular fatty acid. The major ubiquinone was determined to be Q-10. Polar lipids include phosphatidylglycerol, phosphatidylethanolamine, sulfoquinovosyl diacylglycerol, phosphatidylcholine and phosphatidylmonomethylethanolamine. The G+C content of the genomic DNA of strain JG120-1(T) was determined to be 57.8 mol %. DNA-DNA relatedness data indicated that strain JG120-1(T) represents a distinct species that is separate from H. phototrophica DFL-43(T), H. marina LMG128(T) and H. alexandrii AM1 V30(T). On the basis of polyphasic evidences, it is proposed that strain JG120-1(T) (= KCTC 23107(T) = JCM 16715(T)) represents the type strain of a novel species, Hoeflea halophila sp. nov.

Draft Genome Sequence of Granulicatella sp. Strain S8, Isolated from a Marine Fish, Seriola quinqueradiata.

In this study, Granulicatella sp. strain S8 was isolated from the gut of a marine fish, Seriola quinqueradiata, and the draft genome was sequenced. Various genes responsible for pathogenesis, metabolite biosynthesis, defense, and lactic acid production were predicted. The genome sequence of this facultative anaerobe provides insights into its distinctive features.