Description ofOceanospirillum kriegii sp. nov. andO. jannaschii sp. nov. and assignment of two species ofAlteromonas to this genus asO. commune comb. nov. andO. vagum comb. nov

Oceanobacter antarcticus sp. nov., isolated from surface seawater of the Weddell Sea in Antarctica

The poles of the Earth harbour many novel micro-organisms that have not yet been isolated and identified. Here, a Gram-stain-negative, motile, aerobic and rod-shaped bacterial strain, designated as wDCs-4T, was isolated from surface seawater collected from the Weddell Sea in Antarctica. It grows at 4-40 °C (optimum 10-15 °C), pH 4-8 (optimum 7) and in the presence of 0-4% NaCl (w/v, optimum 0.5-1%). The complete 16S rRNA gene of strain wDCs-4T had maximum sequence identity with Oceanobacter mangrovi SM2-42T (97.2%), followed by Thalassolituus oleivorans MIL-1T (96.5%) and Oceanobacter kriegii 197T (96.2%). Phylogenetic analyses based on the 16S rRNA gene and genome sequences showed that strain wDCs-4T was closely clustered with the members of the genus Oceanobacter and formed an independent clade, which could be considered a monophyletic taxon. The average nucleotide identity values between strain wDCs-4T and the members of the genera Oceanobacter and Thalassolituus were 77.7-78.1 and 77.4-80.5%, respectively. The corresponding digital DNA‒DNA hybridization values are 19.5-20.1 and 20.5-22.4%, respectively. The major fatty acids (>5%) of strain wDCs-4T comprised summed feature 5 (C18:0 ante/C18:2  ω6,9c or C18:2  ω6,9c/C18:0 ante) and C16:0. The predominant respiratory was Q-8. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, aminolipids and unknown polar lipids. The draft genome size was 4.58 Mbp, with a DNA G+C content of 53.4 mol%. On the basis of polyphasic analyses, strain wDCs-4T represented a novel species in the genus Oceanobacter, for which the name Oceanobacter antarcticus sp. nov. was proposed. The type strain was wDCs-4T (=MCCC 1A20726T=KCTC 8314T).

Microbial influence on the larval survival of Japanese eel Anguilla japonica: Antibiotic-mediated alterations and biomarker isolation

In rearing systems for the Japanese eel Anguilla japonica, although it is assumed that microorganisms influence larval survival and mortality, particularly during the early stages of growth, the effects of bacterial communities on larval survival have yet to be sufficiently determined. In this study, we compared the bacterial communities associated with larval survival at three stages of eel growth. To artificially alter bacterial communities and assess larval survival, eel larvae were treated with 11 types of antibiotic, and larval survival and bacterial characteristics were compared between the antibiotic-treated and antibiotic-free control groups. Throughout the three growth stages, eels treated with four antibiotics (polymyxin B, tetracycline, novobiocin, and erythromycin) had survival rates higher than those in the control groups. The bacterial communities of surviving larvae in the control and antibiotic groups and dead larvae in the control groups were subsequently analyzed using 16S rRNA gene amplicon sequencing. PERMANOVA analysis indicated that these three larval groups were characterized by significantly different bacterial communities. We identified 14 biomarker amplicon sequence variants (ASVs) of bacterial genera such as Oceanobacter, Alcanivorax, Marinobacter, Roseibium, and Sneathiella that were enriched in surviving larvae in the antibiotic treatment groups. In contrast, all four biomarker ASVs enriched in dead larvae of the control groups were from bacteria in the genus Vibrio. Moreover, 52 bacterial strains corresponding to nine biomarkers were isolated using a culture method. To the best of our knowledge, this is the first study to evaluate the bacterial communities associated with the survival and mortality of larvae in during the early stages of Japanese eel growth and to isolate biomarker bacterial strains. These findings will provide valuable insights for enhancing larval survival in the eel larval rearing systems from a microbiological perspective.

Distribution and survival strategies of endemic and cosmopolitan diazotrophs in the Arctic Ocean

Dinitrogen (N₂) fixation is the major source of reactive nitrogen in the ocean and has been considered to occur specifically in low-latitude oligotrophic oceans. Recent studies have shown that N₂ fixation also occurs in the polar regions and thus is a global process, although the physiological and ecological characteristics of polar diazotrophs are not yet known. Here, we successfully reconstructed diazotroph genomes, including that of cyanobacterium UCYN-A (Candidatus 'Atelocyanobacterium thalassa'), from metagenome data corresponding to 111 samples isolated from the Arctic Ocean. These diazotrophs were highly abundant in the Arctic Ocean (max., 1.28% of the total microbial community), suggesting that they have important roles in the Arctic ecosystem and biogeochemical cycles. Further, we show that diazotrophs within genera Arcobacter, Psychromonas, and Oceanobacter are prevalent in the <0.2 µm fraction in the Arctic Ocean, indicating that current methods cannot capture their N₂ fixation. Diazotrophs in the Arctic Ocean were either Arctic-endemic or cosmopolitan species from their global distribution patterns. Arctic-endemic diazotrophs, including Arctic UCYN-A, were similar to low-latitude-endemic and cosmopolitan diazotrophs in genome-wide function, however, they had unique gene sets (e.g., diverse aromatics degradation genes), suggesting adaptations to Arctic-specific conditions. Cosmopolitan diazotrophs were generally non-cyanobacteria and commonly had the gene that encodes the cold-inducible RNA chaperone, which presumably makes their survival possible even in deep, cold waters of global ocean and polar surface waters. This study shows global distribution pattern of diazotrophs with their genomes and provides clues to answering the question of how diazotrophs can inhabit polar waters.

Genome-based taxonomic rearrangement of Oceanobacter-related bacteria including the description of Thalassolituus hydrocarbonoclasticus sp. nov. and Thalassolituus pacificus sp. nov. and emended description of the genus Thalassolituus

Oceanobacter-related bacteria (ORB) are a group of oligotrophic marine bacteria play an underappreciated role in carbon cycling. They have been frequently described as one of the dominant bacterial groups with a wide distribution in coastal and deep seawater of global oceans. To clarify their taxonomic affiliation in relation to alkane utilization, phylogenomic and comparative genomics analyses were performed based on currently available genomes from GenBank and four newly isolated strains, in addition to phenotypic and chemotaxonomic characteristics. Consistently, phylogenomic analysis robustly separated them into two groups, which are accordingly hydrocarbon-degrading (HD, Thalassolituus and Oleibacter) and non-HD (NHD, Oceanobacter). In addition, the two groups can also be readily distinguished by several polyphasic taxonomic characteristics. Furthermore, both AAI and POCP genomic indices within the HD group support the conclusion that the members of the genus Oleibacter should be transferred into the genus Thalassolituus. Moreover, HD and NHD bacteria differed significantly in terms of genome size, G + C content and genes involved in alkane utilization. All HD bacteria contain the key gene alkB encoding an alkane monooxygenase, which can be used as a marker gene to distinguish the members of closely related genera Oceanobacter and Thalassolituus. Pangenome analysis revealed that the larger accessory genome may endow Thalassolituus with the flexibility to cope with the dynamics of marine environments and thrive therein, although they possess smaller pan, core- and unique-genomes than Oceanobacter. Within the HD group, twelve species were clearly distinguished from each other by both dDDH and ANI genomic indices, including two novel species represented by the newly isolated strains alknpb1M-1 ^T and 59MF3M-4 ^T , for which the names Thalassolituus hydrocarbonoclasticus sp. nov. and Thalassolituus pacificus sp. nov. are proposed. Collectively, these findings build a phylogenetic framework for the ORB and contribute to understanding of their role in marine carbon cycling.

Marinobacterium arenosum sp. nov., isolated from a coastal sand

A Gram-negative, aerobic, motile, rod-shaped bacterium, designated strain CAU 1594^T, was isolated from a coastal sand sample collected in the Republic of Korea. Cells of strain CAU 1594^T grew best at 30 °C, pH 7.5, and in the presence of 1% (w/v) NaCl. Phylogenetic analysis, based on 16S rRNA gene sequencing, indicated that strain CAU 1594^T was affiliated with the genus Marinobacterium and most similar to Marinobacterium jannaschii ATCC 27135^T (95.1%) and Marinobacterium stanieri ATCC 27130^T (94.9%). The whole genome of strain CAU 1594^T was 4,917,683 bp, including 4,188 CDSs, with a 60.4 mol% G + C content. Based on draft genome sequences, the average nucleotide identity and digital DNA-DNA hybridization values of strain CAU 1594^T were within the ranges of 71.9-73.1% and 20.0-2.1%, respectively, compared to reference strains. The major respiratory quinone was ubiquinone-8, and the major fatty acids were C_16:0, summed feature 3 (C_16:1 ω6c and C_16:1 ω7c), and summed feature 8 (C_18:1 ω6c and C_18:1 ω7c). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. Based on these results, strain CAU 1594^T represents a novel species of the genus Marinobacterium, for which the name Marinobacterium arenosum sp. nov. is proposed. The type strain is CAU 1594^T (=KCTC 82405^T=MCCC 1K05672^T).

Oceanobacter mangrovi Sp. Nov., a Novel Poly-β-hydroxybutyrate Accumulating Bacterium Isolated from Mangrove Sediment

A Gram-stain-negative, rod-shaped, motile, mesophilic, and aerobic bacterial strain, designated SM2-42 ^T was isolated from a mangrove sediment. Catalase activity and oxidase activity were positive. Growth was observed at 20 °C-40 °C, pH 6.0-8.0, and in the presence of 0.5-5.0% NaCl. Cells of strain SM2-42 ^T contained poly-β-hydroxybutyrate granules. The 16S rRNA gene of strain SM2-42 ^T had maximum sequence similarity with Oceanobacter kriegii 197 ^T of 97.1%. Phylogenetic analysis based on 16S rRNA gene sequence and 120 conserved concatenated proteins indicated that strain SM2-42 ^T was affiliated to the genus Oceanobacter and formed a monophyletic branch with O. kriegii 197 ^T. The average nucleotide identity and digital DNA-DNA hybridization values between strain SM2-42 ^T and O. kriegii 197 ^T were 76.43% and 21.60%, respectively. The major isoprenoid quinone was Q-8. The major fatty acids (> 10%) comprised C_16:0, summed feature 8 (C_18:1ω7c and C_18:1 ω6c), C_18:0, and summed feature 3 (C_16:1ω7c and/or C_16:1 ω6c). The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminolipid and two unidentified lipids. The draft genome size was 5,115,008 bp with DNA G + C content of 54.3%. Based on phylogenetic analyses and whole genomic comparisons, strain SM2-42 ^T represented a novel species, for which the name Oceanobacter mangrovi sp. nov. was proposed. The type strain was SM2-42 ^T (= MCCC 1K06300^T = KCTC 82938 ^T).

Venatorbacter cucullus gen. nov sp. nov a novel bacterial predator

A novel Gram-stain negative, aerobic, halotolerant, motile, rod-shaped, predatory bacterium ASxL5^T, was isolated from a bovine slurry tank in Nottinghamshire, UK using Campylobacter hyointestinalis as prey. Other Campylobacter species and members of the Enterobacteriaceae were subsequently found to serve as prey. Weak axenic growth on Brain Heart Infusion agar was achieved upon subculture without host cells. The optimal growth conditions were 37 °C, at pH 7. Transmission electron microscopy revealed some highly unusual morphological characteristics related to prey availability. Phylogenetic analyses using 16S rRNA gene sequences showed that the isolate was related to members of the Oceanospirillaceae family but could not be classified clearly as a member of any known genus. Whole genome sequencing of ASxL5^T confirmed the relationship to members the Oceanospirillaceae. Database searches revealed that several ASxL5^T share 16S rRNA gene sequences with several uncultured bacteria from marine, and terrestrial surface and subsurface water. We propose that strain ASxL5^T represents a novel species in a new genus. We propose the name Venatorbacter cucullus gen. nov., sp. nov. with ASxL5^T as the type strain.

Taxogenomic and Metabolic Insights into Marinobacterium ramblicola sp. nov., a New Slightly Halophilic Bacterium Isolated from Rambla Salada, Murcia

A Gram-negative, motile, rod-shaped bacteria, designated D7^T, was isolated by using the dilution-to-extinction method, from a soil sample taken from Rambla Salada (Murcia, Spain). Growth of strain D7^T was observed at 15–40 °C (optimum, 37 °C), pH 5–9 (optimum, 7) and 0–7.5% (w/v) NaCl (optimum, 3%). It is facultatively anaerobic. Phylogenetic analysis based on 16S rRNA gene sequence showed it belongs to the genus Marinobacterium. The in silico DDH and ANI against closest Marinobacterium relatives support its placement as a new species within this genus. The major fatty acids of strain D7^T were C_16:0, summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) and summed feature 8 (C_18:1 ω7c/C_18:1 ω6c). The polar lipid profile consists of phosphatidylethanolamine, phosphatidylglycerol and two uncharacterized lipids. Ubiquinone 8 was the unique isoprenoid quinone detected. The DNA G + C content was 59.2 mol%. On the basis of the phylogenetic, phenotypic, chemotaxonomic and genomic characterization, strain D7^T (= CECT 9818^T = LMG 31312^T) represents a novel species of the genus Marinobacterium for which the name Marinobacterium ramblicola sp. nov. is proposed. Genome-based metabolic reconstructions of strain D7^T suggested a heterotrophic and chemolitotrophic lifestyle, as well as the capacity to biosynthetize and catabolize compatible solutes, and to degrade hydrocarbon aromatic compounds.

Distinct capabilities of different Gammaproteobacterial strains on utilizing small peptides in seawater

Proteins and peptides account for 20–75% of marine biota biomass, of which a major fraction is metabolized by bacteria, thus deciphering interactions between bacteria and peptides is important in understanding marine carbon and nitrogen cycling. To better understand capabilities of different bacterial strains on peptide decomposition, four Gammaproteobacteria (Pseudoalteromonas atlantica, Alteromonas sp., Marinobacterium jannaschii, Amphritea japonica) were incubated in autoclaved seawater amended with tetrapeptide alanine-valine-phenylalanine-alanine (AVFA), a fragment of RuBisCO. While AVFA was decomposed greatly by Pseudoalteromonas atlantica and Alteromonas sp, it remained nearly intact in the Marinobacterium jannaschii and Amphritea japonica incubations. Pseudoalteromonas and Alteromonas decomposed AVFA mainly through extracellular hydrolysis pathway, releasing 71–85% of the AVFA as hydrolysis products to the surrounding seawater. Overall, this study showed that Gammaproteobacterial strains differ greatly in their capabilities of metabolizing peptides physiologically, providing insights into interactions of bacteria and labile organic matter in marine environments.

A Host-Produced Quorum-Sensing Autoinducer Controls a Phage Lysis-Lysogeny Decision

Vibrio cholerae uses a quorum-sensing (QS) system composed of the autoinducer 3,5-dimethylpyrazin-2-ol (DPO) and receptor VqmA (VqmA_Vc), which together repress genes for virulence and biofilm formation. vqmA genes exist in Vibrio and in one vibriophage, VP882. Phage-encoded VqmA (VqmA_Phage) binds to host-produced DPO, launching the phage lysis program via an antirepressor that inactivates the phage repressor by sequestration. The antirepressor interferes with repressors from related phages. Like phage VP882, these phages encode DNA-binding proteins and partner antirepressors, suggesting that they, too, integrate host-derived information into their lysis-lysogeny decisions. VqmA_Phage activates the host VqmA_Vc regulon, whereas VqmA_Vc cannot induce phage-mediated lysis, suggesting an asymmetry whereby the phage influences host QS while enacting its own lytic-lysogeny program without interference. We reprogram phages to activate lysis in response to user-defined cues. Our work shows that a phage, causing bacterial infections, and V. cholerae, causing human infections, rely on the same signal molecule for pathogenesis.

Draft Genome Sequence of the Salt Water Bacterium Oceanospirillum linum ATCC 11336T

Oceanospirillum linum ATCC 11336T is an aerobic, bipolar-tufted gammaproteobacterium first isolated in the Long Island Sound in the 1950s. This announcement offers a genome sequence for O. linum ATCC 11336T, which has a predicted genome size of 3,782,189 bp (49.13% G+C content) containing 3,540 genes and 3,361 coding sequences.

Genomic sequence of 'Candidatus Liberibacter solanacearum' haplotype C and its comparison with haplotype A and B genomes

Haplotypes A and B of 'Candidatus Liberibacter solanacearum' (CLso) are associated with diseases of solanaceous plants, especially Zebra chip disease of potato, and haplotypes C, D and E are associated with symptoms on apiaceous plants. To date, one complete genome of haplotype B and two high quality draft genomes of haplotype A have been obtained for these unculturable bacteria using metagenomics from the psyllid vector Bactericera cockerelli. Here, we present the first genomic sequences obtained for the carrot-associated CLso. These two genomic sequences of haplotype C, FIN114 (1.24 Mbp) and FIN111 (1.20 Mbp), were obtained from carrot psyllids (Trioza apicalis) harboring CLso. Genomic comparisons between the haplotypes A, B and C revealed that the genome organization differs between these haplotypes, due to large inversions and other recombinations. Comparison of protein-coding genes indicated that the core genome of CLso consists of 885 ortholog groups, with the pan-genome consisting of 1327 ortholog groups. Twenty-seven ortholog groups are unique to CLso haplotype C, whilst 11 ortholog groups shared by the haplotypes A and B, are not found in the haplotype C. Some of these ortholog groups that are not part of the core genome may encode functions related to interactions with the different host plant and psyllid species.

Marinobacterium profundum sp. nov., a marine bacterium from deep-sea sediment

A Gram-stain-negative, rod-shaped and motile strain, designated PAMC 27536^T, was isolated from deep-sea sediment in the East Sea, Korea. Analysis of the 16S rRNA gene sequence of the strain showed an affiliation with the genus Marinobacterium. Phylogenetic analyses revealed that strain PAMC 27536^T was related most closely to Marinobacterium rhizophilum CL-YJ9^T with a 16S rRNA gene sequence similarity of 98.5 % and to other members of the genus Marinobacterium (94.0-91.7 %). Genomic relatedness analyses between strain PAMC 27536^T and M. rhizophilum KCCM 42386^T gave an average nucleotide identity of 85.6 % and an estimated DNA-DNA hybridization of 24.6 % using the genome-to-genome distance calculator, indicating that they represent genomically distinct species. Cells of strain PAMC 27536^T grew optimally at 25-30 °C and pH 7.0-7.5 in the presence of 3 % (w/v) sea salts. The major cellular fatty acids were C_16 : 1ω6c and/or C_16 : 1ω7c, C_18 : 1ω6c and/or C_18 : 1ω7c, and C_16 : 0. The major isoprenoid quinone was Q-8. The genomic DNA G+C content was 56.1-57.2 mol%. Based on the phylogenetic, chemotaxonomic, genomic and phenotypic data presented, a novel species with the name Marinobacterium profundum sp. nov. is proposed, with PAMC 27536^T ( = KCCM 43095^T = JCM 30410^T) as the type strain.

Marinobacterium mangrovicola sp. nov., a marine nitrogen-fixing bacterium isolated from mangrove roots of Rhizophora mangle

A nitrogen-fixing marine bacterium, designated strain Gal22(T), was isolated from mangrove roots of Rhizophora mangle. Cells were Gram-stain-negative rods, motile with a single polar flagellum. Growth was observed at 4-42 °C, pH 5.5 to 10 and with 0-18 % (w/v) NaCl. Strain Gal22(T) was positive for catalase and oxidase. Q-8 was the predominant lipoquinone. The DNA G+C content was 57.0 mol%. Based on phylogenetic analysis of 16S rRNA gene, strain Gal22(T) belongs to the genus Marinobacterium. The closely related strains were shown to be Marinobacterium lutimaris DSM 22012(T) and Marinobacterium litorale IMCC1877(T) with 99 % and 96 % 16S rRNA gene sequence similarity, respectively. DNA-DNA relatedness analysis indicated that strain Gal22(T) was different from M. lutimaris DSM 22012(T). On the basis of genotypic, morphological and biochemical characteristics, a novel species, Marinobacterium mangrovicola sp. nov. (type strain, Gal22(T) = DSM 27697(T) = CIP 110653(T)), is proposed.

Oleibacter marinus gen. nov., sp. nov., a bacterium that degrades petroleum aliphatic hydrocarbons in a tropical marine environment

Three Gram-negative, motile, mesophilic, aerobic, rod-shaped bacterial strains, designated 2O1T, 1O14 and 1O18, were isolated from Indonesian seawater after enrichment with crude oil and a continuous supply of supplemented seawater. The strains exhibited high n-alkane-degrading activity, which indicated that the strains were important degraders of petroleum aliphatic hydrocarbons in tropical marine environments. Phylogenetic analyses based on 16S rRNA gene sequences of members of the Gammaproteobacteria showed that the isolates formed a coherent and distinct cluster in a stable lineage containing Oceanobacter kriegii IFO 15467T (96.4–96.5 % 16S rRNA gene sequence similarity) and Thalassolituus oleivorans MIL-1T. DNA G +C content was 53.0–53.1 mol%. The major fatty acids were C16 : 0, C16 : 1 ω7 and C18 : 1 ω9 and the hydroxy fatty acids were C12 : 0 3-OH and C10 : 0 3-OH. The polar lipids were phosphatidylglycerol, a ninhydrin-positive phospholipid(s) and glycolipids. The major quinone was Q-9 (97–99 %), which distinguished the isolates from Oceanobacter kriegii NBRC 15467T (Q-8; 91 %). On the basis of phenotypic, genotypic and chemotaxonomic data, including DNA–DNA hybridization, the isolates represent a novel genus and species, for which the name Oleibacter marinus gen. nov., sp. nov. is proposed. The type strain of Oleibacter marinus is 2O1T (=NBRC 105760T =BTCC B-675T).

Marinobacterium coralli sp. nov., isolated from mucus of coral (Mussismilia hispida)

A Gram-negative, aerobic bacterium, designated R-40509T, was isolated from mucus of the reef builder coral (Mussismilia hispida) located in the São Sebastião Channel, São Paulo, Brazil. The strain was oxidase-positive and catalase-negative, and required Na+ for growth. Its phylogenetic position was in the genus Marinobacterium and the closest related species were Marinobacterium sediminicola, Marinobacterium maritimum and Marinobacterium stanieri; the isolate exhibited 16S rRNA gene sequence similarities of 97.5–98.0 % with the type strains of these species. 16S rRNA gene sequence similarities with other type strains of the genus Marinobacterium were below 96 %. DNA–DNA hybridizations between strain R-40509T and the type strains of the phylogenetically closest species of the genus Marinobacterium revealed less than 70 % DNA–DNA relatedness, supporting the novel species status of the strain. Phenotypic characterization revealed that the strain was able to grow at 15–42 °C and in medium containing up to 9 % NaCl. The isolate could be differentiated from phenotypically related species by several features, including its ability to utilize d-alanine, l-alanine, bromosuccinic acid, β-hydroxybutyric acid and α-ketovaleric acid, but not acetate or l-arabinose. It produced acetoin (Voges–Proskauer), but did not have esterase lipase (C8) or catalase activities. It possessed C18 : 1 ω7c (35 %), summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c; 25 %) and C16 : 0 (22 %) as major cellular fatty acids. The DNA G+C content was 58.5 mol%. The name Marinobacterium coralli sp. nov. is proposed to accommodate this novel isolate; the type strain is R-40509T (=LMG 25435T =CAIM 1449T).

Bermanella marisrubri gen. nov., sp. nov., a genome-sequenced gammaproteobacterium from the Red Sea

A novel heterotrophic, marine, strictly aerobic, motile bacterium was isolated from the Red Sea at a depth of 1 m. Analysis of its 16S rRNA gene sequence, retrieved from the whole-genome sequence, showed that this bacterium was most closely related to the genera Oleispira, Oceanobacter and Thalassolituus, each of which contains a single species, within the class Gammaproteobacteria. Phenotypic, genotypic and phylogenetic analyses supported the creation of a novel genus and species to accommodate this bacterium, for which the name Bermanella marisrubri gen. nov., sp. nov. is proposed. The type strain of Bermanella marisrubri is RED65(T) (=CECT 7074(T) =CCUG 52064(T)).

Marinobacterium litorale sp. nov. in the order Oceanospirillales

A bacterial strain named IMCC1877T was obtained from surface seawater collected near the coast of Deokjeok island (Yellow Sea), using a standard dilution-plating method. The strain was Gram-negative, chemoheterotrophic and facultatively anaerobic, requiring NaCl, and cells were motile rods with a single polar flagellum. Colonies on marine agar were very small (average diameter 0.1 mm). Based on 16S rRNA gene sequences, the most closely related species to strain IMCC1877T was Marinobacterium stanieri (93.7 % sequence similarity to the type strain). Phylogenetic analyses based on 16S rRNA gene sequences showed that this marine isolate belonged to the order Oceanospirillales and formed an independent phyletic line within the clade forming the genus Marinobacterium. The DNA G+C content of the strain was 60.7 mol% and the predominant constituents of the cellular fatty acids were C18 : 1 ω7c (36.6 %), C16 : 1 ω7c and/or iso-C15 : 0 2-OH (26.7 %) and C16 : 0 (24.3 %). Based on the taxonomic data, only a distant relationship could be established between strain IMCC1877T and other Marinobacterium species; the strain therefore represents a novel species of the genus Marinobacterium, for which the name Marinobacterium litorale sp. nov. is proposed. The type strain is IMCC1877T (=KCTC 12756T=LMG 23872T).

Neptuniibacter caesariensis gen. nov., sp. nov., a novel marine genome-sequenced gammaproteobacterium

A Gram-negative, slightly halophilic, strictly aerobic, motile chemoorganotrophic bacterium, strain MED92T, was isolated from a surface water sample from the eastern Mediterranean Sea. Phylogenetic analysis based on its 16S rRNA gene sequence, retrieved from the whole-genome sequence, demonstrated that this isolate is unique, showing <93 % sequence similarity to species of the families Oceanospirillaceae and Alteromonadaceae. The polar lipid profile of the novel strain consisted of phosphatidylethanolamine, phosphatidylglycerol, an unknown aminophospholipid and diphosphatidylglycerol. Major fatty acids are 16 : 1ω7c/15 iso 2-OH (41.2 % relative amount), 18 : 1ω7c (35.9 %), 16 : 0 (16.1 %), 10 : 0 3-OH (5.0 %) and 18 : 0 (1.0 %). Preferred carbon sources are organic acids and amino acids. The DNA G+C content is 46.6 mol%. Based on a phenotypic, chemotaxonomic and phylogenetic analyses, it is proposed that this marine bacterium represents a novel genus and species, for which the name Neptuniibacter caesariensis gen. nov., sp. nov. is proposed. The type strain is MED92T (=CECT 7075T=CCUG 52065T).

Marinobacterium halophilum sp. nov., a marine bacterium isolated from the Yellow Sea

A moderately halophilic, aerobic, Gram-negative bacterium was isolated from a tidal flat area of Dae-Chun, Chung-Nam, Korea. The strain, designated mano11T, comprised rod-shaped cells that were motile by means of polar flagella. It grew with 3–12 % NaCl and at 4–37 °C and pH 5.3–9.3. The predominant menaquinone present in this strain was MK-7 and diaminopimelic acid was not found in the cell-wall peptidoglycan. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain mano11T belongs to the genus Marinobacterium. Strain mano11T exhibited 92.8–98.3 % 16S rRNA gene sequence similarity when compared with the type strains of three other species of the genus Marinobacterium. DNA–DNA hybridization between strain mano11T and Marinobacterium georgiense DSM 11526T, its closest relative in terms of 16S rRNA gene sequence similarity, was 13 %. On the basis of the phenotypic, genetic and phylogenetic data, strain mano11T represents a novel species of the genus Marinobacterium, for which the name Marinobacterium halophilum sp. nov. is proposed. The type strain is mano11T (=KCTC 12240T=DSM 17586T).

Marinomonas aquamarina sp. nov., isolated from oysters and seawater

The characterization of three bacterial strains isolated from cultured oysters and seawater at the Spanish Mediterranean coast has been performed. Strains were phenotypically and genetically characterized and the results led us to identify them as members of the genus Marinomonas. A phylogenetic analysis based on the almost complete 16S rDNA sequences clustered all three strains together (with sequence similarities around 99.8%) in the vicinity of M. communis and M. vaga sequences and distantly related to the other four species of the genus. The most closely related species was M. communis that shared 97.4-97.6% with the Mediterranean strains. DNA-DNA hybridizations were performed to clarify the taxonomic position of our isolates and the results confirmed their specific isolation, with interspecific binding ratios below 59%. We propose the bacteria to constitute a new Marinomonas species, i.e. M. aquamarina and strain 11SM4T (CECT 5080T, CIP 108405T, CCUG 49439T) as the type strain.

Kangiella koreensis gen. nov., sp. nov. and Kangiella aquimarina sp. nov., isolated from a tidal flat of the Yellow Sea in Korea

Two Gram-negative, non-motile, non-spore-forming, rod-shaped organisms, strains SW-125T and SW-154T, were isolated from tidal flat sediment of the Yellow Sea in Korea, and subjected to a polyphasic taxonomic study. Strains SW-125T and SW-154T grew optimally at 30–37 °C and in the presence of 2–3 % (w/v) NaCl. They contained ubiquinone-8 (Q-8) as the predominant respiratory lipoquinone and iso-C15 : 0 as the major fatty acid. The DNA G+C contents of strains SW-125T and SW-154T were 44 mol%. Phylogenetic trees based on 16S rRNA gene sequences revealed that the two strains form deep evolutionary lineages of descent within the γ-Proteobacteria. Strains SW-125T and SW-154T exhibited 16S rRNA gene sequence similarity levels of less than 90 % to members of the γ-Proteobacteria used in this analysis. Strains SW-125T and SW-154T showed a 16S rRNA gene sequence similarity level of 98·5 % and a mean DNA–DNA relatedness level of 9·4 %. Therefore, on the basis of phenotypic, phylogenetic and genomic data, a new genus, Kangiella gen. nov., is proposed to accommodate the novel strains, comprising two novel species, Kangiella koreensis sp. nov. (type strain, SW-125T=KCTC 12182T=DSM 16069T) and Kangiella aquimarina sp. nov. (type strain, SW-154T=KCTC 12183T=DSM 16071T).

Thalassolituus oleivorans gen. nov., sp. nov., a novel marine bacterium that obligately utilizes hydrocarbons

An aerobic, heterotrophic, Gram-negative, curved bacterial strain, designated MIL-1T, was isolated by extinction dilution from an n-tetradecane enrichment culture that was established from sea water/sediment samples collected in the harbour of Milazzo, Italy. In the primary enrichment, the isolate formed creamy-white, medium-sized colonies on the surface of the agar. The isolate did not grow in the absence of NaCl; growth was optimal at 2·7 % NaCl. Only a narrow spectrum of organic compounds, including aliphatic hydrocarbons (C7–C20), their oxidized derivatives and acetate, were used as growth substrates. The isolate was not able to grow under denitrifying conditions. The DNA G+C content and genome size of strain MIL-1Twere estimated to be 53·2 mol% and 2·2 Mbp, respectively. The major cellular and phospholipid fatty acids were palmitoleic, palmitic and oleic acids (33·5, 29·5 and 11·0 % and 18, 32 and 31 %, respectively). 3-Hydroxy lauric acid was the only hydroxy fatty acid detected. Thirteen different compounds that belonged to two types of phospholipid (phosphatidylethylamine and phosphatidylglycerol) were identified. 16S rRNA gene sequence analysis revealed that this isolate represents a distinct phyletic lineage within theγ-Proteobacteriaand has about 94·4 % sequence similarity toOceanobacter kriegii(the closest bacterial species with a validly published name). The deduced protein sequence of the putative alkane hydrolase, AlkB, of strain MIL-1Tis related to the corresponding enzymes ofAlcanivorax borkumensisandPseudomonas oleovorans(81 and 80 % similarity, respectively). On the basis of the analyses performed,Thalassolituus oleivoransgen. nov., sp. nov. is described. Strain MIL-1T(=DSM 14913T=LMG 21420T) is the type and only strain ofT. oleivorans.

Oleispira antarctica gen. nov., sp. nov., a novel hydrocarbonoclastic marine bacterium isolated from Antarctic coastal sea water

The taxonomic characteristics of two bacterial strains, RB-8(T) and RB-9, isolated from hydrocarbon-degrading enrichment cultures obtained from Antarctic coastal marine environments (Rod Bay, Ross Sea), were determined. These bacteria were psychrophilic, aerobic and Gram-negative with polar flagella. Growth was not observed in the absence of NaCl, occurred only at concentrations of Na+ above 20 mM and was optimal at an NaCl concentration of 3-5% (w/v). The major cellular fatty acids were monounsaturated straight-chain fatty acids. The strains were able to synthesize the polyunsaturated fatty acid eicosapentaenoic acid (20: 5omega3) at low temperatures. The DNA G + C contents were 41-42 mol%. The strains formed a distinct phyletic line within the gamma-Proteobacteria, with less than 89.6% sequence identity to their closest relatives within the Bacteria with validly published names. Both isolates exhibited a restricted substrate profile, with a preference for aliphatic hydrocarbons, that is typical of marine hydrocarbonoclastic micro-organisms such as Alcanivorax, Marinobacter and Oleiphilus. On the basis of ecophysiological properties, G + C content, 16S rRNA gene sequences and fatty acid composition, a novel genus and species within the gamma-Proteobacteria are proposed, Oleispira antarctica gen. nov., sp. nov.; strain RB-8(T) (= DSM 14852(T) = LMG 21398(T)) is the type strain.