Maribrevibacterium harenarium gen. nov., sp. nov., represented by a marine strain of the family Oceanospirillaceae.

A Gram-stain-negative, non-motile, facultatively anaerobic, short rod-shaped bacterium, designated HB171799T, was isolated from seacoast sandy soil collected at Qishui Bay, Hainan, PR China. The chemotaxonomic analysis revealed that the respiratory quinones were Q-8 and Q-7, and the major cellular fatty acids were summed feature 8 (comprising C18 : 1 ω7c and/or C18 : 1 ω6c), C16 : 0 and C18 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid and an unidentified lipid. The size of the draft genome was 3.68 Mb with a DNA G+C content of 48.0 mol%. Results of phylogenetic analyses based on 16S rRNA gene and genome sequences showed that the novel isolate belonged to the family Oceanospirillaceae and formed a distinct subcluster at the base of the radiation of the genus Marinomonas. The highest sequence similarity (96.0 %) of the novel isolate was found to the type strains of Marinomonas fungiae JCM 18476T and Marinomonas ostreistagni DSM23425T. The whole genome-based phylogeny and differences in cellular fatty acids and polar lipids readily distinguished strain HB171799T from all the closely related validly published type strains. Strain HB171799T is therefore suggested to represent a novel species of a new genus in the family Oceanospirillaceae, for which the name Maribrevibacterium harenarium gen. nov., sp. nov. is proposed. The type strain is HB171799T (=CGMCC 1.16727T=JCM 33332T).

Neptunomonas marina sp. nov., isolated from seawater.

Strain HPM-16T, isolated from seawater, was characterized using a polyphasic taxonomy approach. Phylogenetic analyses based on 16S rRNA gene sequences and coding sequences of an up-to-date bacterial core gene set (92 protein clusters) indicated that strain HPM-16T formed a phylogenetic lineage in the genus Neptunomonas. Strain HPM-16T was most closely related to Neptunomonas concharum LHW37T with 16S rRNA gene sequence similarity of 96.7%. Cells were Gram-stain negative, facultatively anaerobic, motile by means of a single polar flagellum, rod-shaped and formed white colonies. Optimal growth occurred at 30-35 °C, pH 6.5-8, and in the presence of 2-5% NaCl. C18:1ω7c and summed feature 3 (C16:1ω7c and/or C16:1ω6c) were the predominant fatty acids. The only isoprenoid quinone was Q-8. The polar lipid profile revealed the presence of phosphatidylethanolamine, phosphatidylglycerol and several uncharacterized lipids. The major polyamines were putrescine and spermidine. The draft genome was approximately 3.68 Mb in size with a G + C content of 50.5 mol%. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain HPM-16T should be classified as a novel species of the genus Neptunomonas, for which the name Neptunomonas marina sp. nov. is presented. The type strain is HPM-16T (= BCRC 80980T = LMG 29560T = KCTC 52235T).

Metagenomic and metatranscriptomic responses of natural oil degrading bacteria in the presence of dispersants.

Oil biodegradation has been extensively studied in the wake of the deepwater horizon spill, but the application of dispersant to oil spills in marine environments remains controversial. Here, we report metagenomic (MG) and metatranscriptomic (MT) data mining from microcosm experiments investigating the oil degrading potential of Canadian west and east coasts to estimate the gene abundance and activity of oil degrading bacteria in the presence of dispersant. We found that the addition of dispersant to crude oil mainly favours the abundance of Thalassolituus in the summer and Oleispira in the winter, two key natural oil degrading bacteria. We found a high abundance of genes related not only to n-alkane and aromatics degradation but also associated with transporters, two-component systems, bacterial motility, secretion systems and bacterial chemotaxis.

Marinobacterium aestuarii sp. nov., a benzene-degrading marine bacterium isolated from estuary sediment.

A Gram-stain-negative, aerobic, motile, flagellated rod-shaped bacterium, designated ST58-10T, was isolated from an estuarine sediment in the Republic of Korea. The strain was able to degrade benzene. Growth of strain ST58-10T was observed at 4-35 °C (optimum, 20-25 °C), pH 5-9 (optimum, pH 7-8) and 1-8 % NaCl (optimum, 3 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain ST58-10T formed a phyletic lineage within the genus Marinobacterium of the family Oceanospirillaceae. Strain ST58-10T was most closely related to Marinobacterium profundum PAMC 27536T (99.6 %) and Marinobacterium rhizophilum CL-YJ9T (98.3 %), and to other members of the genus Marinobacterium(94.5-91.5 %). However, the mean value estimated by using the Genome-to-Genome Distance Calculator was 50.6±7.4 % with M. profundum PAMC 27536T and 30.9±2.8 with M. rhizophilum CL-YJ9T, respectively. An average nucleotide identity value was 89.0 % with M. profundum PAMC 27536T and 85.6 % with M. rhizophilum CL-YJ9T, respectively. The major fatty acids of strain ST58-10T were summed feature 3 (comprising C16 : 1ω7c/C16 : 1ω6c), summed feature 8 (comprising C18 : 1 ω7c/C18 : 1ω6c), C16 : 0 and C10 : 0 3-OH, and contained ubiquinone (Q-8) as the sole isoprenoid quinone. Phosphatidylethanolamine, phosphatidylglycerol, three unidentified aminolipids, an unidentified glycolipid and an unidentified lipid were detected as polar lipids. The DNA G+C content of strain ST58-10T was 58.78 mol%. On the basis of the phenotypic, chemotaxonomic and molecular properties, strain ST58-10T represents a novel species of the genus Marinobacterium, for which the name Marinobacterium aestuarii sp. nov. is proposed. The type strain is ST58-10T (=KCTC 52193T=NBRC 112103T).

Litoribrevibacter euphylliae sp. nov., isolated from the torch coral Euphyllia glabrescens.

Strain Eup a-2T, isolated from the torch coral Euphyllia glabrescens, was characterized using a polyphasic taxonomy approach. Cells of strain Eup a-2T were Gram-negative, aerobic and motile by three polar flagella and formed translucent colonies. Optimal growth occurred at 25 °C, pH 6-8 and in the presence of 2-4 % NaCl. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Eup a-2T belonged to the genus Litoribrevibacter and showed the highest levels of sequence similarity with respect to Litoribrevibacter albus Y32T (97.8 %). Strain Eup a-2T contained summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0 as the predominant fatty acids. The predominant isoprenoid quinone was Q-8. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphophatidylglycerol. Genomic DNA G+C content of strain Eup a-2T was 49.1 mol%. The DNA-DNA hybridization value for strain Eup a-2T with L. albus Y32T was less than 30 %. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain Eup a-2T should be classified as a novel species of the genus Litoribrevibacter, for which the name Litoribrevibactereuphylliae sp. nov. is presented. The type strain is Eup a-2T (=BCRC 81004T=LMG 29725T=KCTC 52438T).

Neptuniibacter pectenicola sp. nov. and Neptuniibacter marinus sp. nov., two novel species isolated from a Great scallop (Pecten maximus) hatchery in Norway and emended description of the genus Neptuniibacter.

Nine isolates obtained from a great scallop hatchery in Norway were characterized using a polyphasic approach. Strains were Gram-negative, aerobic and motile rods with oxidative metabolism. Phylogenetic analysis based on the sequences of 16S rRNA and rpoB genes showed that these strains formed two different groups associated with members of the genus Neptuniibacter. DNA-DNA hybridization (DDH) and Average Nucleotide Identity (ANI) demonstrated that the isolates constituted two novel species of this genus, which can be phenotypically differentiated from their closest relatives. The names Neptuniibacter marinus sp. nov. and Neptuniibacter pectenicola sp. nov are proposed, with ATR 1.1T (=CECT 8938T=DSM 100783T) and LFT 1.8T (=CECT 8936T=DSM 100781T) as respective type strains.

Bacterioplanoides pacificum gen. nov., sp. nov., isolated from seawater of South Pacific Gyre.

A Gram-staining-negative, strictly aerobic, transparent and smooth, curved-rod-shaped motile bacterium with a single polar flagellum, designated strain sw100T, was isolated from surface seawater of South Pacific Gyre during Integrated Ocean Drilling Program Expedition 329. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain sw100T was most closely related to the member of the family Oceanospirillaceae and was distinct from the most closely related genera Bacterioplanes, Thalassolituus and Oceanobacter (95.8, 94.5-95.3 and 94.4 % 16S rRNA gene sequence similarities, respectively). Growth occurred in the presence of 0-11 % NaCl (w/v, optimum 7 %), at 10-37 °C (optimum 28 °C) and pH 6.0-9.0 (optimum pH 7.0). The major fatty acids (>10 % of total fatty acids) are C16 : 0, C16 : 0 N alcohol and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c). The major polar lipids were phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and two unidentified polar lipids. The DNA G+C content of strain sw100T was 55.3 mol%. The major respiratory quinone was ubiquinone-10 (Q-10). On the basis of polyphasic analyses, strain sw100T is considered to represent a novel species in a novel genus of the family Oceanospirillaceae, for which the name Bacterioplanoides pacificum gen. nov., sp. nov. is proposed. The type strain is sw100T (=JCM 30597T=MCCC 1K00501T=KCTC 42424T).

Description of Endozoicomonas ascidiicola sp. nov., isolated from Scandinavian ascidians.

Two gram-negative, facultative anaerobic, chemoorganoheterotrophic, motile and rod-shaped bacteria, strains AVMART05(T) and KASP37, were isolated from ascidians (Tunicata, Ascidiaceae) of the genus Ascidiella collected at Gullmarsfjord, Sweden. The strains are the first cultured representatives of an ascidian-specific lineage within the genus Endozoicomonas (Gammaproteobacteria, Oceanospirillales, Hahellaceae). Both strains feature three distinct 16S rRNA gene paralogs, with identities of 98.9-99.1% (AVMART05(T)) and 97.7-98.8% (KASP37) between paralogs. The strains are closely related to Endozoicomonas atrinae and Endozoicomonas elysicola, with which they share 97.3-98.0% 16S rRNA gene sequence identity. Digital DNA-DNA hybridization, average nucleotide identity, and tetra-nucleotide correlation analysis indicate that both strains belong to a single species distinct from their closest relatives. Both strains feature similar DNA G+C contents of 46.70mol% (AVMART05(T)) and 44.64mol% (KASP37). The fatty acid patterns of AVMART05(T) and KASP37 are most similar to those of Endozoicomonas euniceicola and Endozoicomonas gorgoniicola. Based on the polyphasic approach, we propose the species Endozoicomonas ascidiicola sp. nov. to accommodate the newly isolated strains. E. ascidiicola sp. nov. is represented by the type strain AVMART05(T) (=DSM 100913(T)=LMG 29095(T)) and strain KASP37 (=DSM 100914=LMG 29096).

Nitrincola nitratireducens sp. nov. isolated from a haloalkaline crater lake.

The novel, cream coloured, Gram-negative-staining, rod-shaped, motile bacteria, designated strains AK23(T) and AK28, were isolated from sediment samples collected from Lonar Lake, Buldhana district, India. The predominant fatty acids were C18:1ω7c, C16:0, C10:0 3OH and C16:1ω7c and/or iso-C15:0 2OH (summed feature 3). Polar lipid content of strains AK23(T) and AK28 were found to be phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphotidylserine (PS), one unidentified phospholipid (PL) and two unidentified lipids (L1 and L2). The 16S rRNA gene sequence analysis indicated strains AK23(T) and AK28 as the members of the genus Nitrincola and closely related to the type strain Nitrincola lacisaponensis with pair-wise sequence similarity of 97.67% and 97.62% respectively. DNA-DNA hybridization between strain AK23(T) and AK28 showed a relatedness of 91%. Genome of strains AK23(T) and N. lacisaponensis DSM 16316(T) were sequenced. A comparative genomics approach was used to study strains AK23(T), N. lacisaponensis DSM 16316(T) and five other phylogenetic neighbours. The genome size of N. lacisaponensis DSM 16316(T) was found to be 614,784bp smaller than that of the strain AK23(T). This variation could be due to multiple reasons, gene uptake, evolution, mutation, genome reduction phenomenon and draft nature of sequencing. Based on data from the current polyphasic study, strains AK23(T) and AK28 are proposed as novel species of the genus Nitrincola, for which the name Nitrincola nitratireducens sp. nov. is proposed. The type strain of N. nitratireducens is AK23(T) (=JCM 18788(T)=MTCC 11628(T)).

Amphritea spongicola sp. nov., isolated from a marine sponge, and emended description of the genus Amphritea.

A Gram-stain-negative, rod-shaped (1.2-2.1 µm × 0.8-0.9 µm), flagellated and motile marine bacterium, designated MEBiC05461T, was isolated from a marine sponge inhabiting Micronesia. Strain MEBiC05461T was oxidase-negative and catalase-positive. Growth was observed at 8.0-35.6 °C (optimum 30.0 °C), at pH 5.0-9.0 (optimum pH 7.0) and with 1.5-6.0 % (w/v, optimum 2.0-2.5 %) NaCl. 16S rRNA gene sequence analysis revealed that strain MEBiC05461T showed high similarity to members of the genus Amphritea (96.4-96.6 %). The predominant cellular fatty acids were C16:0 (23.9 %), summed feature 3 (C16:1ω7c and/or C16:1ω6c; 39.7 %) and summed feature 8 (C18:1ω7c and/or C18:1ω6c; 22.0 %). The DNA G+C content was 48.5 mol%. The major respiratory quinone was Q-8.Phosphatidylethanolamine, phosphatidylglycerol, one unidentified glycolipid, one unidentified aminolipid, one unidentified glycophospholipid and two unidentified lipids were detected as the major polar lipids. On the basis of the data from this polyphasic taxonomic study, strain MEBiC05461T should be classified as a representative of a novel species in the genus Amphritea, and the name proposed is Amphritea spongicola sp. nov. The type strain is MEBiC05461T ( = KCCM 42943T = JCM 16668T). Emendations of the genus Amphritea and species Amphritea atlanticaGärtner et al. 2008 and Amphritea balenaeMiyazaki et al. 2008 are were also given.

Neptunomonas phycophila sp. nov. isolated from a culture of Symbiodinium sp., a dinoflagellate symbiont of the sea anemone Aiptasia tagetes.

A Gram-stain-negative, facultatively anaerobic, oxidase- and catalase-positive, rod-shaped bacterium, strain SYM1(T), was isolated from a culture of Symbiodinium sp., an algal symbiont of the sea anemone Aiptasia tagetes collected in Puerto Rico. Growth was observed at 4-40 °C (optimum 30 °C), at pH 5.0-11.0 (optimum pH 8.0) and with 0.5-8 % (optimum 2 %) (w/v) NaCl. Phylogenetic analyses of 16S rRNA gene sequences showed that strain SYM1(T) was a member of the genus Neptunomonas with the type strain of Neptunomonas naphthovorans as the closest phylogenetic relative with a pairwise sequence similarity of 98.15 %. However, DNA-DNA relatedness between strain SYM1(T) and N. naphthovorans CIP 106451(T) was 24 %. Moreover, strain SYM1(T) could be distinguished from its closest relative by several phenotypic characteristics such as NaCl, pH and temperature tolerance, nitrate reduction and utilization of carbon substrates. The major cellular fatty acids were C16 : 0, C18 : 1ω7c and summed feature 3 (comprising C16 : 1ω7c and/or iso-C15 : 0 2-OH). The genomic DNA G+C content of strain SYM1(T) was 45 mol%. Ubiquinone-8 (Q-8) was the only respiratory quinone detected. Based on a polyphasic taxonomic characterization, strain SYM1(T) represents a novel species of the genus Neptunomonas, for which the name Neptunomonas phycophila sp. nov. is proposed. The type strain is SYM1(T) ( = LMG 28329(T) = CECT 8716(T)).

Pelagitalea pacifica gen. nov., sp. nov., a new marine bacterium isolated from seawater.

A strictly aerobic, Gram-negative, beige-pigmented, short-rod-shaped, non-motile and chemoheterotrophic bacteria, designated K2-48(T) was isolated from seawater collected in the Western North Pacific Ocean near Japan. Preliminary analysis based on the 16S rRNA gene sequence revealed that the novel isolate was affiliated with the family Oceanospirillaceae within the class Gammaproteobacteria and that it showed the highest sequence similarity (93.7 %) to Neptunomonas qingdaonensis P10-2-4(T). The strain could be differentiated phenotypically from recognized members of the family Oceanospirillaceae. The major fatty acids of strain K2-48(T) were identified as summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH) and C16:0 as defined by the MIDI system. The DNA G+C content was determined to be 43.2 mol%, the major respiratory quinone was identified as ubiquinone 9 and a polar lipid profile was present consisting of phosphatidylethanolamine, a phosphatidylglycerol and an unidentified phospolipid. On the basis of polyphasic taxonomic studies, it was concluded that strain K2-48(T) represents a novel genus sp. We propose the name Pelagitalea pacifica gen. nov., sp. nov. for this strain; its type strain is K2-48(T) (=KCCM 90119(T)).

Neptunomonas acidivorans sp. nov., isolated from sediment, and emended description of the genus Neptunomonas.

A Gram-reaction-negative, aerobic, rod-shaped (1.2-1.6 µm×0.6-0.8 µm), flagellated and motile marine bacterium, designated MEBiC06243(T), was isolated from a sediment collected at Daebu Island in the Yellow Sea (37° 20' N 126° 41' E), Korea. The 16S rRNA gene sequence analysis revealed that strain MEBiC06243(T) showed high similarity with Neptunomonas naphthovorans NAG-2N-126(T) (96.3%). Growth was observed at 10-39 °C (optimum 29 °C), at pH 6.0-9.0 (optimum pH 7) and with 0-7% (optimum 2.5%) NaCl. The predominant cellular fatty acids were C(10:0) 3-OH (6.1%), C(12:0) (5.8%), C(16:0) (30.5%), C(18:1)ω7c (21.6%) and summed feature 3 (comprising C(15:0) 2-OH and/or C(16:1)ω7c; 30.7%). The DNA G+C content was 41.4 mol%. The major respiratory quinone was Q-8. Phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified lipids, one unidentified aminophospholipid and three unidentified aminolipids were detected as major polar lipids. On the basis of this polyphasic taxonomic data, strain MEBiC06243(T) should be classified as a novel species of the genus Neptunomonas proposed as Neptunomonas acidivorans sp. nov. The type strain is MEBiC06243(T) ( =KCCM 42975(T) =JCM 18291(T)). An emended description of the genus Neptunomonas is also given.

Metagenome, metatranscriptome and single-cell sequencing reveal microbial response to Deepwater Horizon oil spill.

The Deepwater Horizon oil spill in the Gulf of Mexico resulted in a deep-sea hydrocarbon plume that caused a shift in the indigenous microbial community composition with unknown ecological consequences. Early in the spill history, a bloom of uncultured, thus uncharacterized, members of the Oceanospirillales was previously detected, but their role in oil disposition was unknown. Here our aim was to determine the functional role of the Oceanospirillales and other active members of the indigenous microbial community using deep sequencing of community DNA and RNA, as well as single-cell genomics. Shotgun metagenomic and metatranscriptomic sequencing revealed that genes for motility, chemotaxis and aliphatic hydrocarbon degradation were significantly enriched and expressed in the hydrocarbon plume samples compared with uncontaminated seawater collected from plume depth. In contrast, although genes coding for degradation of more recalcitrant compounds, such as benzene, toluene, ethylbenzene, total xylenes and polycyclic aromatic hydrocarbons, were identified in the metagenomes, they were expressed at low levels, or not at all based on analysis of the metatranscriptomes. Isolation and sequencing of two Oceanospirillales single cells revealed that both cells possessed genes coding for n-alkane and cycloalkane degradation. Specifically, the near-complete pathway for cyclohexane oxidation in the Oceanospirillales single cells was elucidated and supported by both metagenome and metatranscriptome data. The draft genome also included genes for chemotaxis, motility and nutrient acquisition strategies that were also identified in the metagenomes and metatranscriptomes. These data point towards a rapid response of members of the Oceanospirillales to aliphatic hydrocarbons in the deep sea.

Neptuniibacter halophilus sp. nov., isolated from a salt pan, and emended description of the genus Neptuniibacter.

A bacterial strain designated antisso-13(T) was isolated from a salt pan in southern Taiwan and characterized using a polyphasic taxonomic approach. Strain antisso-13(T) was gram-negative, aerobic, creamy white in colour, rod-shaped and motile by single monopolar flagellum. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain antisso-13(T) belonged to the genus Neptuniibacter and its closest neighbour was Neptuniibacter caesariensis MED92(T), with 96.7 % sequence similarity. Phylogenetic analyses based on rpoB and recA gene sequences and deduced amino acid sequences also revealed that the novel strain and N. caesariensis MED92(T) formed a distinct phylogenetic cluster. Strain antisso-13(T) exhibited optimal growth at 25-30 °C, with 2.0-4.0 % NaCl and at pH 7.0. Cellular fatty acids were C(16 : 1)ω7c (39.8 %), C(18 : 1)ω7c (29.4 %), C(16 : 0) (15.5 %), C(10 : 0) 3-OH (7.5 %), anteiso-C(11 : 0) (1.8 %), C(18 : 0) (1.8 %), C(11 : 0) 2-OH (1.6 %), iso-C(10 : 0) (1.2 %) and C(14 : 0) (1.1 %). The major respiratory quinone was ubiquinone Q-8. The polar lipid profile consisted of a mixture of phosphatidylglycerol, phosphatidylethanolamine and several uncharacterized polar lipids and the DNA G+C content was 54.2 mol%. The results of physiological and biochemical tests allowed clear phenotypic differentiation of this isolate from previously described members of the genus Neptuniibacter. It is evident from the genotypic and phenotypic data that strain antisso-13(T) should be classified as a representative of a novel species in the genus Neptuniibacter. The name proposed for this taxon is Neptuniibacter halophilus sp. nov.; the type strain is antisso-13(T) ( = LMG 25378(T) = BCRC 80079(T)). An emended description of the genus Neptuniibacter is provided.

Deep-sea oil plume enriches indigenous oil-degrading bacteria.

The biological effects and expected fate of the vast amount of oil in the Gulf of Mexico from the Deepwater Horizon blowout are unknown owing to the depth and magnitude of this event. Here, we report that the dispersed hydrocarbon plume stimulated deep-sea indigenous γ-Proteobacteria that are closely related to known petroleum degraders. Hydrocarbon-degrading genes coincided with the concentration of various oil contaminants. Changes in hydrocarbon composition with distance from the source and incubation experiments with environmental isolates demonstrated faster-than-expected hydrocarbon biodegradation rates at 5°C. Based on these results, the potential exists for intrinsic bioremediation of the oil plume in the deep-water column without substantial oxygen drawdown.

Neptunomonas antarctica sp. nov., isolated from marine sediment.

A Gram-negative, motile, oxidase- and catalase-positive and facultatively aerobic bacterium, designated S3-22T, was isolated from marine sediment of the Nella Fjord, Antarctica. Strain S3-22T reduced nitrate to nitrite and grew at pH 6.0-8.0, at 4-25 degrees C and with 0.5-5% (w/v) NaCl. It contained Q-8 as the only respiratory quinone and summed feature 3 (C16:1omega7c and/or iso-C15:0 2-OH), C16:0 and C18:1omega7c as the major cellular fatty acids. The genomic DNA G+C content was 45.6 mol%. Phylogenetic analyses of 16S rRNA gene sequences showed that strain S3-22T was affiliated with the genus Neptunomonas, with 97.1% sequence similarity to Neptunomonas japonica JAMM 0745T and 94.8% to Neptunomonas naphthovorans NAG-2N-126T, the type strains of the only two recognized Neptunomonas species. DNA-DNA relatedness between strain S3-22T and N. japonica JCM 14595T was 20.4%. Strain S3-22T could be distinguished from the type strains of Neptunomonas species by several phenotypic properties. Based on the evidence from our polyphasic study, strain S3-22T represents a novel Neptunomonas species, for which the name Neptunomonas antarctica sp. nov. is proposed. The type strain is S3-22T (=CCTCC AB 209086T =KACC 14056T).

Marinomonas polaris sp. nov., a psychrohalotolerant strain isolated from coastal sea water off the subantarctic Kerguelen islands.

Two aerobic, psychrohalotolerant, motile bacterial isolates, CK13T and CK16, isolated from sea-water samples collected off the subantarctic Kerguelen island, were characterized by using a polyphasic taxonomic approach. On the basis of 16S rRNA gene sequence data, the strains were 99.6% similar and exhibited 93-97% similarity with the seven recognized species of Marinomonas. The most closely related species were Marinomonas pontica and Marinomonas primoryensis, with 97 and 96 % similarity at the 16S rRNA gene sequence level, respectively. DNA-DNA hybridization values between strain CK13T and M. pontica and M. primoryensis were only 58 and 40%, respectively. The major fatty acids present in strain CK13T were iso-C(16:0), C(16:0), C(16:1)omega7c and C(18:1)omega7c. The DNA G+C content of strain CK13T was 41.2 mol%. Phosphatidylethanolamine and phosphatidylglycerol were identified as the predominant phospholipids. All the above characteristics support the affiliation of strain CK13T to the genus Marinomonas. Phylogenetic analysis and phenotypic and genotypic distinctiveness confirmed that strains CK13T and CK16 are members of a novel species of the genus Marinomonas, for which the name Marinomonas polaris sp. nov. is proposed. The type strain is CK13T (=MTCC 6645T=DSM 16579T=JCM 12522T).

Identification of an operon involved in tyrosinase activity and melanin synthesis in Marinomonas mediterranea.

The genomic region of Marinomonas mediterranea containing the genes required for tyrosinase activity and melanin synthesis has been cloned by marker rescue using the transposon-generated, amelanogenic strain T105. Five ORFs, two incomplete and three complete, have been sequenced in the genomic region where the transposon was inserted. RT-PCR analysis indicates that ORF 3, coding for tyrosinase, and ORF4, coding for a protein of 250 amino acids, are in the same transcriptional unit, constituting an operon whose promoter region has been determined by 5'-RACE. This operon has been sequenced in the wild-type and several mutant strains, indicating that both ORFs are required for expression of tyrosinase activity and melanin synthesis. The nitrosoguanidine generated, amelanogenic mutant ng56, shows a nonsense mutation in ORF3 coding for the tyrosinase. On the other hand, in the strain T105 the transposon is inserted in ORF4. The product of this gene is related to copper metabolism, since the addition of this metal ion to cell extracts or culture media partially restores melanin synthesis and tyrosinase activity in the strain T105. However, it does not show significant sequence similarity to previously characterized metallochaperones and hence may be an example of a new kind of those proteins. The operon has been denoted as ppoB, taking into consideration that ppoA denotes the M. mediterranea gene coding for the previously cloned polyphenol oxidase with laccase activity. This is the first demonstration of the tyrosinase gene forming part of an operon in a Gram-negative bacterium.