Heme auxotrophy in abundant aquatic microbial lineages.

Heme, a porphyrin ring complexed with iron, is a metalloprosthetic group of numerous proteins involved in diverse metabolic and respiratory processes across all domains of life, and is thus considered essential for respiring organisms. Several microbial groups are known to lack the de novo heme biosynthetic pathway and therefore require exogenous heme from the environment. These heme auxotroph groups are largely limited to pathogens, symbionts, or microorganisms living in nutrient-replete conditions, whereas the complete absence of heme biosynthesis is extremely rare in free-living organisms. Here, we show that the acI lineage, a predominant and ubiquitous free-living bacterial group in freshwater habitats, is auxotrophic for heme, based on the experimental or genomic evidence. We found that two recently cultivated acI isolates require exogenous heme for their growth. One of the cultured acI isolates also exhibited auxotrophy for riboflavin. According to whole-genome analyses, all (n = 20) isolated acI strains lacked essential enzymes necessary for heme biosynthesis, indicating that heme auxotrophy is a conserved trait in this lineage. Analyses of >24,000 representative genomes for species clusters of the Genome Taxonomy Database revealed that heme auxotrophy is widespread across abundant but not-yet-cultivated microbial groups, including Patescibacteria, Marinisomatota (SAR406), Actinomarinales (OM1), and Marine groups IIb and III of Euryarchaeota Our findings indicate that heme auxotrophy is a more common phenomenon than previously thought, and may lead to use of heme as a growth factor to increase the cultured microbial diversity.

Discovery of Terminal Oxazole-Bearing Natural Products by a Targeted Metabologenomic Approach.

A targeted metabologenomic method was developed to selectively discover terminal oxazole-bearing natural products from bacteria. For this, genes encoding oxazole cyclase, a key enzyme in terminal oxazole biosynthesis, were chosen as the genomic signature to screen bacterial strains that may produce oxazole-bearing compounds. Sixteen strains were identified from the screening of a bacterial DNA library (1,000 strains) using oxazole cyclase gene-targeting polymerase chain reaction (PCR) primers. The PCR amplicon sequences were subjected to phylogenetic analysis and classified into nine clades. 1H-13C coupled-HSQC NMR spectra obtained from the culture extracts of the hit strains enabled the unequivocal detection of the target compounds, including five new oxazole compounds, based on the unique 1JCH values and chemical shifts of oxazole: lenzioxazole (1) possessing an unprecedented cyclopentane, permafroxazole (2) bearing a tetraene conjugated with carboxylic acid, tenebriazine (3) incorporating two modified amino acids, and methyl-oxazolomycins A and B (4 and 5). Tenebriazine displayed inhibitory activity against pathogenic fungi, whereas methyl-oxazolomycins A and B (4 and 5) selectively showed anti-proliferative activity against estrogen receptor-positive breast cancer cells. This metabologenomic method enables the logical and efficient discovery of new microbial natural products with a target structural motif without the need for isotopic labeling.

Targeted and Logical Discovery of Piperazic Acid-Bearing Natural Products Based on Genomic and Spectroscopic Signatures.

A targeted and logical discovery method was devised for natural products containing piperazic acid (Piz), which is biosynthesized from ornithine by l-ornithine N-hydroxylase (KtzI) and N-N bond formation enzyme (KtzT). Genomic signature-based screening of a bacterial DNA library (2020 strains) using polymerase chain reaction (PCR) primers targeting ktzT identified 62 strains (3.1%). The PCR amplicons of KtzT-encoding genes were phylogenetically analyzed to classify the 23 clades into two monophyletic groups, I and II. Cultivating hit strains in media supplemented with 15NH4Cl and applying 1H-15N heteronuclear multiple bond correlation (HMBC) along with 1H-15N heteronuclear single quantum coherence (HSQC) and 1H-15N HSQC-total correlation spectroscopy (HSQC-TOCSY) NMR experiments detected the spectroscopic signatures of Piz and modified Piz. Chemical investigation of the hit strains prioritized by genomic and spectroscopic signatures led to the identification of a new azinothricin congener, polyoxyperuin B seco acid (1), previously reported chloptosin (2) in group I, depsidomycin D (3) incorporating two dehydropiperazic acids (Dpz), and lenziamides A and B (4 and 5), structurally novel 31-membered cyclic decapeptides in group II. By consolidating the phylogenetic and chemical analyses, clade-structure relationships were elucidated for 19 of the 23 clades. Lenziamide A (4) inhibited STAT3 activation and induced G2/M cell cycle arrest, apoptotic cell death, and tumor growth suppression in human colorectal cancer cells. Moreover, lenziamide A (4) resensitized 5-fluorouracil (5-FU) activity in both in vitro cell cultures and the in vivo 5-FU-resistant tumor xenograft mouse model. This work demonstrates that the genomic and spectroscopic signature-based searches provide an efficient and general strategy for new bioactive natural products containing specific structural motifs.

Genomic and Spectroscopic Signature-Based Discovery of Natural Macrolactams.

The logical and effective discovery of macrolactams, structurally unique natural molecules with diverse biological activities, has been limited by a lack of targeted search methods. Herein, a targeted discovery method for natural macrolactams was devised by coupling genomic signature-based PCR screening of a bacterial DNA library with spectroscopic signature-based early identification of macrolactams. DNA library screening facilitated the efficient selection of 43 potential macrolactam-producing strains (3.6% of 1,188 strains screened). The PCR amplicons of the amine-deprotecting enzyme-coding genes were analyzed to predict the macrolactam type (α-methyl, α-alkyl, or ß-methyl) produced by the hit strains. 1H-15N HSQC-TOCSY NMR analysis of 15N-labeled culture extracts enabled macrolactam detection and structural type assignment without any purification steps. This method identified a high-titer Micromonospora strain producing salinilactam (1), a previously reported α-methyl macrolactam, and two Streptomyces strains producing new α-alkyl and ß-methyl macrolactams. Subsequent purification and spectroscopic analysis led to the structural revision of 1 and the discovery of muanlactam (2), an α-alkyl macrolactam with diene amide and tetraene chromophores, and concolactam (3), a ß-methyl macrolactam with a [16,6,6]-tricyclic skeleton. Detailed genomic analysis of the strains producing 1-3 identified putative biosynthetic gene clusters and pathways. Compound 2 displayed significant cytotoxicity against various cancer cell lines (IC50 = 1.58 µM against HCT116), whereas 3 showed inhibitory activity against Staphylococcus aureus sortase A. This genomic and spectroscopic signature-based method provides an efficient search strategy for new natural macrolactams and will be generally applicable for the discovery of nitrogen-bearing natural products.

Thermomonas paludicola sp. nov., isolated from a lotus wetland.

A Gram-stain-negative, aerobic, rod-shaped and motile bacterium, designated IMCC34681T, was isolated from a lotus wetland in the Republic of Korea. Cellular growth occurred at 10-37 °C (optimum, 30 °C), pH 6-9 (optimum, pH 7) and with 0-2 % (w/v) NaCl (optimum, 0.5 % NaCl). The results of 16S rRNA gene sequence analysis indicated that IMCC34681T represented a member of the genus Thermomonas, sharing 95.3-96.9 % similarities with type strains of species of the genus. The whole-genome sequence of IMCC34681T was 2.72 Mbp in size with 66.2 % DNA G+C content. The IMCC34681T genome shared the highest average nucleotide identity (ANI) value, 82.8 %, with that of Thermomonas brevis KACC 16975T among species of the genus Thermomonas, indicating that the strain represents a novel genomic species. The major respiratory quinone of the strain was ubiquinone-8 (Q-8) and the predominant cellular fatty acids were iso-C15 : 0 (25.7 %) and iso-C14 : 0 (20.8 %). The strain harboured diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified lipid as major fatty polar lipids. On the basis of the phylogenetic, phenotypic, chemotaxonomic and genomic characteristics, IMCC34681T was assigned to the genus Thermomonas as the type strain of a novel species, for which the name Thermomonas paludicola sp. nov. is proposed. The type strain is IMCC34681T (=KACC 21793T=NBRC 114635T).

Epoxinnamide: An Epoxy Cinnamoyl-Containing Nonribosomal Peptide from an Intertidal Mudflat-Derived Streptomyces sp.

Cinnamoyl-containing nonribosomal peptides (CCNPs) form a unique family of actinobacterial secondary metabolites and display various biological activities. A new CCNP named epoxinnamide (1) was discovered from intertidal mudflat-derived Streptomyces sp. OID44. The structure of 1 was determined by the analysis of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) data along with a mass spectrum. The absolute configuration of 1 was assigned by the combination of advanced Marfey's method, 3JHH and rotating-frame overhauser effect spectroscopy (ROESY) analysis, DP4 calculation, and genomic analysis. The putative biosynthetic pathway of epoxinnamide (1) was identified through the whole-genome sequencing of Streptomyces sp. OID44. In particular, the thioesterase domain in the nonribosomal peptide synthetase (NRPS) biosynthetic gene cluster was proposed as a bifunctional enzyme, which catalyzes both epimerization and macrocyclization. Epoxinnamide (1) induced quinone reductase (QR) activity in murine Hepa-1c1c7 cells by 1.6-fold at 5 µM. It also exhibited effective antiangiogenesis activity in human umbilical vein endothelial cells (IC50 = 13.4 µM).

Taeanamides A and B, Nonribosomal Lipo-Decapeptides Isolated from an Intertidal-Mudflat-Derived Streptomyces sp.

Two new lipo-decapeptides, namely taeanamides A and B (1 and 2), were discovered from the Gram-positive bacterium Streptomyces sp. AMD43, which was isolated from a mudflat sample from Anmyeondo, Korea. The exact molecular masses of 1 and 2 were revealed by high-resolution mass spectrometry, and the planar structures of 1 and 2 were elucidated using NMR spectroscopy. The absolute configurations of 1 and 2 were determined using a combined analysis of 1H-1H coupling constants and ROESY correlations, the advanced Marfey's method, and bioinformatics. The putative nonribosomal peptide synthetase pathway for the taeanamides was identified by analyzing the full genome sequence data of Streptomyces sp. AMD43. We also found that taeanamide A exhibited mild anti-tuberculosis bioactivity, whereas taeanamide B showed significant bioactivity against several cancer cell lines.

Permianibacter fluminis sp. nov., isolated from a freshwater stream.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated as IMCC34836T, was isolated from a freshwater stream. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain IMCC34836T was most closely related to Permianibacter aggregans HW001T (of the family Pseudomonadaceae) with 95.6 % sequence similarity and formed a robust clade with P. aggregans HW001T. The draft genome sequence of strain IMCC34836T was 4.4 Mbp in size with 59.1 mol% DNA G+C content. Average nucleotide identity and digital DNA-DNA hybridization values between strain IMCC34836T and P. aggregans HW001T were 71.2 and 22.0 %, respectively, indicating that the new strain represents a novel species. The strain contained iso-C15 : 0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and summed feature 9 (iso-C17 : 1 ω9c and/or C16 : 1 10-methyl) as the major fatty acids and harboured phosphatidylethanolamine, two unidentified aminophospholipids and three unidentified lipids as major polar lipids. The isoprenoid quinone detected in the strain was ubiquinone-8. Based on the phylogenetic and phenotypic characteristics, strain IMCC34836T is considered to represent a novel species of the genus Permianibacter, for which the name Permianibacter fluminis sp. nov. is proposed. The type strain is IMCC34836T (=KACC 21755T=NBRC 114416T).

Uliginosibacterium aquaticum sp. nov., Isolated from a Freshwater Lake.

A Gram-stain-negative, aerobic, chemoheterotrophic, rod-shaped bacterium motile by a polar flagellum, designated IMCC34675T, was isolated from Chungju Lake, an artificial freshwater reservoir in Republic of Korea. The 16S rRNA gene sequence analysis indicated that strain IMCC34675T belongs to the genus Uliginosibacterium, sharing ≤ 97.1% sequence similarities with the type strains of the genus. Whole genome sequencing of strain IMCC34675T revealed a 4.1 Mbp of genome size with 62.4% of the DNA G + C content. The IMCC34675T genome shared 73.3% of average nucleotide identity and 19.9% of digital DNA-DNA hybridization values to the genome of Uliginosibacterium gangwonense DSM 18521T, the type species of the genus. The major fatty acids of strain IMCC34675T were summed feature 3 (comprising C16:1ω6c and/or C16:1ω7c) and C16:0. The respiratory quinone detected in the strains was ubiquinone-8 (Q-8). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified aminophospholipid, one aminolipid, and five unidentified lipids. Based on the phylogenetic and phenotypic characterization, strain IMCC34675T was considered to represent a novel species within the genus Uliginosibacterium, for which the name Uliginosibacterium aquaticum sp. nov. is proposed with IMCC34675T (= KACC 21758T = NBRC 114418T) as the type strain.

Halioglobus maricola sp. nov., isolated from coastal seawater.

A Gram-stain-negative, rod-shaped, aerobic, non-flagellated, chemoheterotrophic bacterium, designated IMCC14385T, was isolated from surface seawater of the East Sea, Republic of Korea. The 16S rRNA gene sequence analysis indicated that IMCC14385T represented a member of the genus Halioglobus sharing 94.6-97.8 % similarities with species of the genus. Whole-genome sequencing of IMCC14385T revealed a genome size of 4.3 Mbp and DNA G+C content of 56.7 mol%. The genome of IMCC14385T shared an average nucleotide identity of 76.6 % and digital DNA-DNA hybridization value of 21.6 % with the genome of Halioglobus japonicus KCTC 23429T. The genome encoded the complete poly-ß-hydroxybutyrate biosynthesis pathway. The strain contained summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and C17 : 1 ω8c as the predominant cellular fatty acids as well as ubiquinone-8 (Q-8) as the respiratory quinone. The polar lipids detected in the strain were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, five unidentified phospholipids, an unidentified aminolipid, an unidentified aminophospholipid and four unidentified lipids. On the basis of taxonomic data obtained in this study, it is suggested that IMCC14385T represents a novel species of the genus Halioglobus, for which the name Halioglobus maricola sp. nov. is proposed. The type strain is IMCC14385T (=KCTC 72520T=NBRC 114072T).

Genome characteristics and environmental distribution of the first phage that infects the LD28 clade, a freshwater methylotrophic bacterial group.

Bacteriophages infecting major groups of freshwater heterotrophic bacteria have been rarely isolated, hampering analyses of freshwater viromes. Here, we report the isolation and genomic characterization of P19250A, the first phage that infects the LD28 clade, an abundant freshwater methylotrophic bacterial group. P19250A was isolated from Lake Soyang, an oligotrophic reservoir, using an LD28 strain as a host. Morphological and genomic analyses revealed that P19250A is a lytic siphovirus with a ∼38.6-kb genome. To analyze the distribution of P19250A genome within its habitat, six seasonal viral metagenome (virome) samples were prepared from Lake Soyang. Through binning analysis of freshwater viromes, P19250A was shown to be the most highly assigned freshwater phage that infects heterotrophic bacteria (up to 8.21%) in five viromes. Furthermore, when freshwater virome data collected worldwide were analyzed, P19250A genome also showed high abundance, especially in Lough Neagh, UK, where P19250A genome was recorded as the most abundant bacteriophage. From metagenome analysis, the proportion of P19250A-assigned reads showed seasonal fluctuation following the abundance of the LD28 clade in Lake Soyang. These results showed that P19250A would be an essential resource for analyses of freshwater viromes, and also suggest that phages of other abundant freshwater bacteria need to be isolated for better understanding of freshwater viruses.

Expansion of Cultured Bacterial Diversity by Large-Scale Dilution-to-Extinction Culturing from a Single Seawater Sample.

High-throughput cultivation (HTC) based on a dilution-to-extinction method has been applied broadly to the cultivation of marine bacterial groups, which has often led to the repeated isolation of abundant lineages such as SAR11 and oligotrophic marine gammaproteobacteria (OMG). In this study, to expand the phylogenetic diversity of HTC isolates, we performed a large-scale HTC with a single surface seawater sample collected from the East Sea, the Western Pacific Ocean. Phylogenetic analyses of the 16S rRNA genes from 847 putative pure cultures demonstrated that some isolates were affiliated with not-yet-cultured clades, including the OPB35 and Puniceicoccaceae marine group of Verrucomicrobia and PS1 of Alphaproteobacteria. In addition, numerous strains were obtained from abundant clades, such as SAR11, marine Roseobacter clade, OMG (e.g., SAR92 and OM60), OM43, and SAR116, thereby increasing the size of available culture resources for representative marine bacterial groups. Comparison between the composition of HTC isolates and the bacterial community structure of the seawater sample used for HTC showed that diverse marine bacterial groups exhibited various growth capabilities under our HTC conditions. The growth response of many bacterial groups, however, was clearly different from that observed with conventional plating methods, as exemplified by numerous isolates of the SAR11 clade and Verrucomicrobia. This study showed that a large number of novel bacterial strains could be obtained by an extensive HTC from even a small number of samples.

Genome of a SAR116 bacteriophage shows the prevalence of this phage type in the oceans.

The abundance, genetic diversity, and crucial ecological and evolutionary roles of marine phages have prompted a large number of metagenomic studies. However, obtaining a thorough understanding of marine phages has been hampered by the low number of phage isolates infecting major bacterial groups other than cyanophages and pelagiphages. Therefore, there is an urgent requirement for the isolation of phages that infect abundant marine bacterial groups. In this study, we isolated and characterized HMO-2011, a phage infecting a bacterium of the SAR116 clade, one of the most abundant marine bacterial lineages. HMO-2011, which infects "Candidatus Puniceispirillum marinum" strain IMCC1322, has an ~55-kb dsDNA genome that harbors many genes with novel features rarely found in cultured organisms, including genes encoding a DNA polymerase with a partial DnaJ central domain and an atypical methanesulfonate monooxygenase. Furthermore, homologs of nearly all HMO-2011 genes were predominantly found in marine metagenomes rather than cultured organisms, suggesting the novelty of HMO-2011 and the prevalence of this phage type in the oceans. A significant number of the viral metagenome sequences obtained from the ocean surface were best assigned to the HMO-2011 genome. The number of reads assigned to HMO-2011 accounted for 10.3%-25.3% of the total reads assigned to viruses in seven viromes from the Pacific and Indian Oceans, making the HMO-2011 genome the most or second-most frequently assigned viral genome. Given its ability to infect the abundant SAR116 clade and its widespread distribution, Puniceispirillum phage HMO-2011 could be an important resource for marine virus research.

MdsABC-Mediated Pathway for Pathogenicity in Salmonella enterica Serovar Typhimurium.

MdsABC is a Salmonella-specific tripartite efflux pump that has been implicated in the virulence of Salmonella enterica serovar Typhimurium; however, little is known about the virulence factors associated with this pump. We observed MdsABC expression-dependent alterations in the degree of resistance to extracellular oxidative stress and macrophage-mediated killing. Thin-layer chromatography and tandem mass spectrometry analyses revealed that overexpression of MdsABC led to increased secretion of 1-palmitoyl-2-stearoyl-phosphatidylserine (PSPS), affecting the ability of the bacteria to invade and survive in host cells. Overexpression of MdsABC and external addition of PSPS similarly rendered the mdsABC deletion strain resistant to diamide. Diagonal gel analysis showed that PSPS treatment reduced the diamide-mediated formation of disulfide bonds, particularly in the membrane fraction of the bacteria. Salmonella infection of macrophages induced the upregulation of MdsABC expression and led to an increase of intracellular bacterial number and host cell death, similar to the effects of MdsABC overexpression and PSPS pretreatment on the mdsABC deletion strain. Our study shows that MdsABC mediates a previously uncharacterized pathway that involves PSPS as a key factor for the survival and virulence of S. Typhimurium in phagocytic cells.

Celeribacter marinus sp. nov., isolated from coastal seawater.

A Gram-staining-negative, non-motile, non-pigmented and rod-shaped bacterial strain, designated IMCC12053(T), was isolated from coastal surface seawater of the Yellow Sea, Korea. Optimal growth of strain IMCC12053(T) was observed at 30 °C, pH 7.0 and in the presence of 2 % (w/v) NaCl. 16S rRNA gene sequence comparisons showed that strain IMCC12053(T) was most closely related to Celeribacter baekdonensis L-6(T) (97.5 % similarity) and Celeribacter neptunius H 14(T) (96.0 %). Strain IMCC12053(T) formed a robust phylogenetic clade with members of the genus Celeribacter. The DNA-DNA relatedness value between IMCC12053(T) and C. baekdonensis was far lower than 70 % (35.7-42.5 %), which indicated that strain IMCC12053(T) is a novel genomic species of the genus Celeribacter. The major respiratory isoprenoid quinone was ubiquinone-10 (Q-10) and major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and aminolipids. The DNA G+C content was 61.0 mol%. On the basis of genotypic and phenotypic data collected in this study, it is proposed that strain IMCC12053(T) represents a novel species of the genus Celeribacter, for which the name Celeribacter marinus sp. nov. is proposed. The type strain is IMCC12053(T) ( = KACC 17482(T) = NBRC 109702(T)).

Granulosicoccus marinus sp. nov., isolated from Antarctic seawater, and emended description of the genus Granulosicoccus.

A Gram-staining-negative, motile by flagella, non-pigmented, poly-ß-hydroxybutyrate-producing, strictly aerobic and sphere-shaped bacterium, IMCC3490(T), was isolated from a coastal seawater sample from the Antarctic Peninsula. Optimal growth of strain IMCC3490(T) was observed at 20 °C, pH 8.0 and in the presence of 2 % (w/v) NaCl. Phylogenetic analysis using 16S rRNA gene sequences indicated that strain IMCC3490(T) belonged to the genus Granulosicoccus in the family Granulosicoccaceae. The strain was closely related to Granulosicoccus antarcticus IMCC3135(T) (98.8 % 16S rRNA gene sequence similarity) and Granulosicoccus coccoides Z 271(T) (98.5 %). The DNA-DNA relatedness values between IMCC3490(T) and type strains of the two species of the genus were far lower than 70 %, which indicated strain IMCC3490(T) is a novel genomic species of the genus Granulosicoccus. The major fatty acids of strain IMCC3490(T) were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The isoprenoid quinone detected was ubiquinone-8 (Q-8) and predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content was 61.0 mol%. On the basis of phylogenetic analyses, DNA-DNA relatedness values and phenotypic data, it is suggested that strain IMCC3490(T) represents a novel species of the genus Granulosicoccus, for which the name Granulosicoccus marinus sp. nov. is proposed. The type strain is IMCC3490(T) ( = KACC 17483(T) = NBRC 109704(T)). An emended description of the genus Granulosicoccus is also provided.

Ulvibacter marinus sp. nov., isolated from coastal seawater.

A Gram-stain-negative, aerobic, chemoheterotrophic, yellow, non-motile and flexirubin-positive bacterium, designated strain IMCC12008(T), was isolated from coastal seawater of the Yellow Sea and subjected to polyphasic taxonomy. Optimal growth was observed at 25 °C, pH 7.0 and in the presence of 2% (w/v) NaCl. Based on 16S rRNA gene sequence analysis and subsequent phylogenetic analyses, strain IMCC12008(T) belonged to the genus Ulvibacter of the family Flavobacteriaceae, with Ulvibacter antarcticus IMCC3101(T) (96.0%) and Ulvibacter litoralis KMM 3912(T) (95.8%) having the highest sequence similaries. The major fatty acids were iso-C(15 : 0) (26.2%) and iso-C(15 : 1) G (10.5%). The DNA G+C content was 38.1 mol%. Strain IMCC12008(T) contained menaquinone-6 (MK-6) as the respiratory quinone, and polar lipids comprising phosphatidylethanolamine, two unidentified aminolipids and an unknown aminophospholipid. On the basis of data collected from this study, strain IMCC12008(T) ( = NBRC 109484(T) = KCTC 32322(T)) represents a novel species of the genus Ulvibacter, for which the name Ulvibacter marinus sp. nov. is proposed.

Formosa arctica sp. nov., isolated from Arctic seawater.

A Gram-staining-negative, chemoheterotrophic, yellow-pigmented, gliding, catalase- and oxidase-positive, flexirubin-negative, strictly aerobic bacterium, designated strain IMCC9485(T), was isolated from a seawater sample collected from the Arctic Ocean. Optimal growth of strain IMCC9485(T) was observed at 25 °C, pH 7-8 and in the presence of 1.5-2.5 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain IMCC9485(T) belonged to the genus Formosa and was closely related to Formosa algae KCTC 12364(T) (98.2 %) and Formosa agariphila KCTC 12365(T) (98.0 %). DNA-DNA relatedness between the new isolate and F. algae and F. agariphila was far lower than 70 %, which indicated that strain IMCC9485(T) is a novel genomic species of the genus Formosa. The major fatty acids (>10 %) were iso-C15 : 1G (13.7 %), C16 : 1ω7c and/or C16 : 1ω6c (13.4 %) and iso-C15 : 0 (12.3 %). The G+C content of the genomic DNA was 37.6 mol%. Strain IMCC9485(T) contained menaquinone-6 (MK-6) as the respiratory quinone and phosphatidylethanolamine, unknown aminophospholipids and unknown polar lipids as polar lipid constituents. On the basis of phylogenetic analyses and differential phenotypic characteristics, it is suggested that strain IMCC9485(T) ( = KACC 17484(T) = KCCM 42937(T) = NBRC 106080(T)) be assigned to the genus Formosa as the type strain of a novel species, for which the name Formosa arctica sp. nov. is proposed.

Complete genome sequences of two Persicivirga bacteriophages, P12024S and P12024L.

The phylum Bacteroidetes is one of the major bacterial phyla in marine environments, where bacteriophages are highly abundant. Bacteriophages infecting members of the phylum Bacteroidetes, however, have not been well represented in public genome databases. Here we announce the genome sequences of two bacteriophages, P12024S and P12024L, that were isolated from coastal seawater and lytically infect Persicivirga sp. IMCC12024, a marine Bacteroidetes bacterium.

Complete genome sequence of Croceibacter bacteriophage P2559S.

Croceibacter atlanticus HTCC2559(T), a marine bacterium isolated from the Sargasso Sea, is a phylogenetically unique member of the family Flavobacteriaceae. Strain HTCC2559(T) possesses genes related to interaction with primary producers, which makes studies on bacteriophages infecting the strain interesting. Here we report the genome sequence of bacteriophage P2559S, which was isolated off the coast of the Republic of Korea and lytically infects HTCC2559(T). Many genes predicted in the P2559S genome had their homologs in Bacteroides phages.