Byung Cheol Cho

Arcobacter marinus sp. nov.

A slightly curved, rod-shaped marine bacterium, designated strain CL-S1(T), was isolated from near Dokdo, an island in the East Sea, Korea. Cells were Gram-negative and grew well under either aerobic or microaerobic conditions. Analyses of the 16S rRNA and gyrA gene sequences of strain CL-S1(T) revealed an affiliation with the genus Arcobacter within the class Epsilonproteobacteria. Phylogenetic analyses based on 16S rRNA and gyrA gene sequences showed that strain CL-S1(T) formed a robust clade with Arcobacter halophilus LA31B(T), with sequence similarities of 96.1 and 88.2 %, respectively. DNA-DNA relatedness between strain CL-S1(T) and A. halophilus DSM 18005(T) was 44 %, indicating that they represent genomically distinct species. Strain CL-S1(T) grew optimally at 30-37 degrees C, at pH 7 and in the presence of 3-5 % NaCl. The dominant cellular fatty acids were iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c (28.4 %), C(16 : 0) (26.2 %) and C(18 : 1)omega7c (22.3 %). The DNA G+C content of strain CL-S1(T) was 28 mol%. Strain CL-S1(T) differed phenotypically from A. halophilus LA31B(T) based on its ability to grow aerobically at 10 degrees C and inability to grow under anaerobic conditions. Based on the data presented, strain CL-S1(T) is considered to represent a novel species of the genus Arcobacter, for which the name Arcobacter marinus sp. nov. is proposed. The type strain is CL-S1(T) (=KCCM 90072(T) =JCM 15502(T)).

Prokaryotic abundance and 16S rRNA gene sequences detected in marine aerosols on the East Sea (Korea).

Modern studies on marine airborne prokaryotes over open seas have been rare. Here, to understand their distribution and composition, aerosol as well as surface seawater samples were collected at three sites in the East Sea. The abundance of airborne prokaryotes was 0.7-1.2 × 10(5) cells m(-3) . Partial sequences of the 16S rRNA gene from the aerosols were dominated by Gammaproteobacteria and Bacteroidetes. Interestingly, the numbers of phylotypes of airborne bacteria were comparable to those of seawater bacteria in coastal and remote offshore sites. Over half of the bacterial operational taxonomic units (OTUs) detected in these aerosols (12 out of 20) were of marine origin. Eight of the 19 bacterial OTUs found in the surface waters occurred in the aerosols. Thus, surface seawater seems to be a main source of marine airborne bacteria. However, in the intermediate offshore site, airborne bacterial OTUs (n=4) were all terrestrial, indicating that variations of dominant airborne bacterial phylotypes occurred over the sites (each ∼160 km apart) sampled at 1-4-day intervals. Euryarchaeota sequences belonging to the MSP8 clade reported from geographically distant regions were detected in marine aerosols. Long-distance aerial transport of the marine prokaryotes seems to be quite possible.

Halocafeteria seosinensis gen. et sp. nov. (Bicosoecida), a halophilic bacterivorous nanoflagellate isolated from a solar saltern.

Recently, heterotrophic nanoflagellates (HNF) have been reported to actively ingest prokaryotes in high salinity waters. We report the isolation and culture of an HNF from a Korean saltern pond of 300‰ salinity. The organism is biflagellated with an acronematic anterior flagellum and never glides on surfaces. The mitochondria have tubular cristae. Neither transitional helix nor spiral fiber were observed in the transition zones of the flagella. The cell has a cytostome supported by an arc of eight microtubules, suggesting that our isolate is a bicosoecid. Our isolate had neither mastigonemes, lorica, body scales, nor cytopharynx and thus could not be placed in any of the presently described bicosoecid genera. Phylogenetic analysis of 18S rRNA gene sequences from stramenopiles confirmed the bicosoecid affinities of our isolate, but did not place it within any established genus or family. Its closest relatives include Caecitellus and Cafeteria. The optimal range of growth temperature was 30–35°C. The isolated HNF grew optimally at 150‰ salinity and tolerated up to 363‰ salinity, but it failed to grow below 75‰ salinity, indicating that it could be a borderline extreme halophile. On the basis of its morphological features and position in 18S rRNA trees we propose a novel genus for our isolate; Halocafeteria, n. gen. The species name Halocafeteria seosinensis sp. nov. is proposed.

Thalassobaculum litoreum gen. nov., sp. nov., a member of the family Rhodospirillaceae isolated from coastal seawater.

A Gram-negative, facultatively anaerobic strain with slightly curved and straight rod-shaped cells, strain CL-GR58(T), was isolated from coastal seawater (near Gori, Korea). Analyses of the 16S rRNA gene sequence revealed that strain CL-GR58(T) belonged to the family Rhodospirillaceae with Azospirillum lipoferum as its closest relative (gene sequence similarity of 90.9 %). Phylogenetic analyses of the 16S rRNA gene sequences showed that strain CL-GR58(T) was not associated with any known genera in the family Rhodospirillaceae. The novel strain grew in the presence of 1-10 % sea salts, optimally at 30-35 degrees C and pH 8. The major cellular fatty acids consisted of C(18 : 1)omega7c (48.5 %), C(16 : 0) (14.8 %), C(17 : 0) (12.2 %), C(19 : 0) cyclo omega8c (6.3 %) and summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH, 6.0 %). Among the phylogenetically related genera, the fatty acid C(17 : 0) was found only in strain CL-GR58(T). The DNA G+C content of the novel strain was 68.0 mol%. According to phylogenetic analyses of the 16S rRNA gene sequence, fatty acid content and the physiological data, strain CL-GR58(T) represents a novel species in a new genus of the family Rhodospirillaceae, for which the name Thalassobaculum litoreum gen. nov., sp. nov. is proposed. The type strain of the type species is CL-GR58(T) (=KCCM 42674(T)=DSM 18839(T)).

Marivita cryptomonadis gen. nov., sp. nov. and Marivita litorea sp. nov., of the family Rhodobacteraceae, isolated from marine habitats.

Two strictly aerobic, Gram-negative, rod-shaped bacteria containing photosynthesis-related genes, designated strains CL-SK44(T) and CL-JM1(T), were isolated from a culture of the marine phytoplankton Cryptomonas sp. and coastal seawater from Korea, respectively. Phylogenetic analysis of 16S rRNA gene sequences revealed that the two strains were related to members of the genera Thalassobius (95.3-96.7 % similarity), Pelagibaca (95.3-96.0 %) and Donghicola (95.6 %) in the family Rhodobacteraceae. However, the two novel strains did not form a robust clade with any species of the Roseobacter clade, forming a distinct clade. The major polar lipids of the strains were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unidentified aminolipid and an unidentified lipid, profiles that were distinguishable from those of the related genera examined. Although the level of 16S rRNA gene sequence similarity between strains CL-SK44(T) and CL-JM1(T) was very high (99.1 %), DNA-DNA relatedness between the strains was 13 %, suggesting that they represent genomically distinct species. In addition, the two strains could be differentiated based on the presence of a minor polar lipid, on the hydrolysis of gelatin and the utilization of carbon sources. Based on the data from the present study, strains CL-SK44(T) and CL-JM1(T) are considered to represent separate novel species of a new genus of the family Rhodobacteraceae, for which the names Marivita cryptomonadis gen. nov., sp. nov. (type species) and Marivita litorea sp. nov. are proposed. The type strains of Marivita cryptomonadis and Marivita litorea are CL-SK44(T) (=KCCM 90070(T)=JCM 15447(T)) and CL-JM1(T) (=KCCM 90071(T)=JCM 15446(T)), respectively.

Muricauda olearia sp. nov., isolated from crude-oil-contaminated seawater, and emended description of the genus Muricauda.

A Gram-staining-negative, rod-shaped and non-motile bacterium, designated CL-SS4T, was isolated from crude-oil-contaminated seawater from the west coast of Korea and was investigated by means of a polyphasic taxonomic approach. Strain CL-SS4T grew optimally at 25-30 degrees C, at pH 6.8-7.7 and in the presence of 2-3% sea salts. The major fatty acids were iso-C17:0 3-OH, iso-C15:0 and iso-C15:1 G. The major isoprenoid quinone was MK-6. The DNA G+C content was 50.7 mol%. Analysis of the 16S rRNA gene sequence of strain CL-SS4T revealed that it was a member of the genus Muricauda, sharing 95.7-96.9% sequence similarity with the type strains of Muricauda species and being most closely related to Muricauda aquimarina SW-63T. Phylogenetic analyses based on 16S rRNA gene sequences confirmed that strain CL-SS4T formed a deep lineage related to the genus Muricauda. Strain CL-SS4T was distinguishable from recognized Muricauda species on the basis of differential phenotypic characteristics and DNA G+C content. Based on these results, it is proposed that strain CL-SS4T represents a novel species of the genus Muricauda, for which the name Muricauda olearia sp. nov. is proposed. An emended description of the genus Muricauda is also proposed. The type strain is CL-SS4T (=KCCM 90075T=JCM 15563T).

Ponticoccus litoralis gen. nov., sp. nov., a marine bacterium in the family Rhodobacteraceae.

A Gram-negative, coccoid to rod-shaped, strictly aerobic bacterium, strain CL-GR66(T), was isolated from coastal seawater collected off Korea. The strain grew optimally in the presence of 3-5 % sea salts, at a temperature of 30 degrees C and at pH 7. The polar lipid profile of strain CL-GR66(T) comprised phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminolipids, an unidentified glycolipid and an unidentified lipid. The major fatty acids were C(18 : 1)omega7c (71.4 %), 11-methyl C(18 : 1)omega7c (11.3 %), C(16 : 0) (6.4 %)(,) C(18 : 0) (4.6 %) and C(12 : 1) 3-OH (3.0 %). Ubiquinone 10 was the major quinone. The DNA G+C content was 67.9 mol%. 16S rRNA gene sequence analysis revealed that strain CL-GR66(T) belonged to the Roseobacter clade within the family Rhodobacteraceae. Strain CL-GR66(T) was related most closely to the type strain of Marinovum algicola (95.5 % 16S rRNA gene sequence similarity), and sequence similarities between strain CL-GR66(T) and other type species of the Roseobacter clade ranged from 91.8 to 95.4 %. Phylogenetic analyses of 16S rRNA gene sequences showed that strain CL-GR66(T) was not associated with any known genus in the family Rhodobacteraceae. The distinct phylogenetic position of strain CL-GR66(T), its phylogenetic distance from genera of the family Rhodobacteraceae, together with phenotypic data, suggest that the organism represents a novel species of a new genus, for which the name Ponticoccus litoralis gen. nov., sp. nov. is proposed. The type strain of Ponticoccus litoralis is CL-GR66(T) (=KCCM 90028(T) =DSM 18986(T)).

Maribacter antarcticus sp. nov., a psychrophilic bacterium isolated from a culture of the Antarctic green alga Pyramimonas gelidicola

A psychrophilic, Gram-negative, dark orange-pigmented bacterium, designated CL-AP4(T), was isolated from a culture of the green alga Pyramimonas gelidicola obtained from the Southern Ocean. Strain CL-AP4(T) grew optimally at 10 degrees C, in the presence of 3-4 % sea salts and at pH 8. 16S rRNA gene sequence analysis revealed that strain CL-AP4(T) belonged to the family Flavobacteriaceae, with Maribacter arcticus KOPRI 20941(T) as its closest relative (97.2 % similarity). A number of chemotaxonomic characteristics supported affiliation of strain CL-AP4(T) with the genus Maribacter, i.e. iso-C(15 : 0) (17.2 %), iso-C(15 : 1) (16.8 %) and iso-C(17 : 0) 3-OH (14.9 %) were the dominant fatty acids, MK-6 was the major menaquinone and the DNA G+C content was 37.1 mol%. DNA-DNA relatedness between CL-AP4(T) and M. arcticus KOPRI 20941(T) was only 10 %, suggesting that they are genomically distinct species. In addition, strain CL-AP4(T) differed phenotypically from M. arcticus in its optimum growth temperature, its ability to hydrolyse starch, Tween 40 and Tween 80, and production of certain enzymes. On the basis of the results of the polyphasic analysis, strain CL-AP4(T) was classified in the genus Maribacter as belonging to a novel species, for which the name Maribacter antarcticus sp. nov. is proposed; the type strain is CL-AP4(T) (=KCCM 90069(T)=JCM 15445(T)).

Morphology and Molecular Phylogeny of Trimyema koreanum n. sp., a Ciliate from the Hypersaline Water of a Solar Saltern

ABSTRACT. A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293‰) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing. Trimyema koreanum is about 30 × 13 μm in vivo, has usually 23 longitudinal ciliary rows forming two distinct ciliary girdles visible both in vivo and in protargol impregnation. A third indistinct ciliary girdle as well as a girdle of mucocysts is distinguishable only in impregnated cells. We suggest T. koreanum as a new species, differing from the most similar species, T. marinum, by the presence of two distinct ciliary girdles (T. marinum usually has six ciliary girdles clearly visible in living cells and three anterior spirals that encircle the cell completely). Although the number of known 18S rRNA sequences in the genus Trimyema was limited, the Trimyema group including T. koreanum forms a strong clade. The phylogenetic position confirms that the isolate belongs to the genus Trimyema and is different from previously sequenced species. Trimyema koreanum is able to consume both prokaryotes and small eukaryotes (specifically, the alga Dunaliella sp.).

Nocardioides salarius sp. nov., isolated from seawater enriched with zooplankton

A rod-shaped marine bacterium, designated CL-Z59(T), was isolated from seawater enriched with zooplankton. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain CL-Z59(T) belongs to the genus Nocardioides, the highest level of sequence similarity (99.2%) being found with respect to Nocardioides marinisabuli KCCM 42681(T). However, DNA-DNA hybridization experiments between strain CL-Z59(T) and N. marinisabuli KCCM 42681(T) revealed a mean relatedness value of 33%. Cells were Gram-positive, strictly aerobic and non-motile. Strain CL-Z59(T) grew optimally at pH 6-7 and 25-30 degrees C and at a NaCl concentration of 3%. The isolate was characterized chemotaxonomically as having LL-diaminopimelic acid in the cell wall. The major isoprenoid quinone was MK-8(H(4)) and the predominant cellular fatty acid was iso-C(16:0). The DNA G+C content was 73.3 mol%. On the basis of phylogenetic, genotypic and phenotypic data, strain CL-Z59(T) represents a novel species of the genus Nocardioides, for which the name Nocardioides salarius sp. nov. is proposed. The type strain is CL-Z59(T) (=KCCM 42320(T)=DSM 18239(T)).