Maribacter thermophilus sp. nov., isolated from an algal bloom in an intertidal zone, and emended description of the genus Maribacter

Taxonomic, genomic, and ecological insights into a novel Flavobacteriaceae strain from coastal tidal flats

BACKGROUND

Tidal flats are vital coastal ecosystems that play a significant role in organic carbon accumulation and biogeochemical cycles. Members of the family Flavobacteriaceae is known for its ability to degrade complex organic matter, including polysaccharides. However, the ecological roles and metabolic capabilities of Flavobacteriaceae in tidal flat environments remain underexplored.

RESULTS

In this study, we isolated and characterized a novel bacterium, strain NBU2967T, from the tidal flats of Meishan Island in the East China Sea. Phylogenetic and genomic analyses identified this strain as a new genus and species within the family Flavobacteriaceae, for which we propose the name Meishania litoralis gen. nov., sp. nov. Comprehensive polyphasic characterization, including morphological, physiological, chemotaxonomic, and genomic analyses, confirmed its distinct taxonomic status. Genomic analysis revealed a diverse set of carbohydrate-active enzymes (CAZymes), along with multiple metabolic pathways associated with carbon and sulfur cycling, highlighting the strain's potential adaptation to organic-rich marine environments. Comparative genomic and pangenome analyses further demonstrated significant genetic divergence from related taxa. Environmental distribution data revealed that the newly proposed genus Meishania is widely distributed across global marine ecosystems.

CONCLUSIONS

We isolated and characterized a novel bacterium, designated NBU2967T (= KCTC 82912 T = MCCC 1K06391T), for which we propose the name Meishania litoralis gen. nov., sp. nov. This strain is classified as a new genus within the family Flavobacteriaceae. The strain's ability to process both carbon and sulfur compounds underscores its ecological significance in marine ecosystems. These findings provide novel insights into the ecological functions of the family Flavobacteriaceae in coastal tidal flats environments and enhance our understanding of microbial-mediated degradation and transformation of chemical compounds in dynamic coastal ecosystems.

Maribacter halichondriae sp. nov., isolated from the marine sponge Halichondria panicea, displays features of a sponge-associated life style

A new member of the family Flavobacteriaceae (termed Hal144T) was isolated from the marine breadcrumb sponge Halichondria panicea. Sponge material was collected in 2018 at Schilksee which is located in the Kiel Fjord (Baltic Sea, Germany). Phylogenetic analysis of the full-length Hal144T 16S rRNA gene sequence revealed similarities from 94.3 to 96.6% to the nearest type strains of the genus Maribacter. The phylogenetic tree of the 16S rRNA gene sequences depicted a cluster of strain Hal144T with its closest relatives Maribacter aestuarii GY20T (96.6%) and Maribacter thermophilus HT7-2T (96.3%). Genome phylogeny showed that Maribacter halichondriae Hal144T branched from a cluster consisting of Maribacter arenosus, Maribacter luteus, and Maribacter polysiphoniae. Genome comparisons of strain Maribacter halichondriae Hal144T with Maribacter sp. type strains exhibited average nucleotide identities in the range of 75-76% and digital DNA-DNA hybridisation values in the range of 13.1-13.4%. Compared to the next related type strains, strain Hal144T revealed unique genomic features such as phosphoenolpyruvate-dependent phosphotransferase system pathway, serine-glyoxylate cycle, lipid A 3-O-deacylase, 3-hexulose-6-phosphate synthase, enrichment of pseudogenes and of genes involved in cell wall and envelope biogenesis, indicating an adaptation to the host. Strain Hal144T was determined to be Gram-negative, mesophilic, strictly aerobic, flexirubin positive, resistant to aminoglycoside antibiotics, and able to utilize N-acetyl-β-D-glucosamine. Optimal growth occurred at 25-30 °C, within a salinity range of 2-6% sea salt, and a pH range between 5 and 8. The major fatty acids identified were C17:0 3-OH, iso-C15:0, and iso-C15:1 G. The DNA G + C content of strain Hal144T was 41.4 mol%. Based on the polyphasic approach, strain Hal144T represents a novel species of the genus Maribacter, and we propose the name Maribacter halichondriae sp. nov. The type strain is Hal144T (= DSM 114563T = LMG 32744T).

Maribacter aquimaris sp. nov., isolated from seawater adjacent to Fildes Peninsula, Antarctica

A novel Gram-stain-negative, aerobic, and rod-shaped bacterium with gliding motility, named strain ANRC-HE7^T, was isolated from the seawater of Biological Bay adjacent to Fildes Peninsula, Antarctica. The optimal growth of this strain occurred at 28 °C, pH 7.5, and in the presence of 1.0% (w/v) NaCl. Strain ANRC-HE7^T can produce amylase and harbors gene clusters involved in cellulose degradation. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain ANRC-HE7^T formed a distinct lineage within the genus Maribacter and was closely related to Maribacter luteus RZ05^T (98.4% sequence similarity), Maribacter polysiphoniae LMG 23671^T (98.3%), and Maribacter arenosus CAU 1321^T (97.3%). However, digital DNA-DNA hybridization and average nucleotide identity values between strain ANRC-HE7^T and closely related strains were 17.4-49.1% and 70.9-92.7%, much lower than the cutoff values of 70% and 95%, respectively. On the other hand, strain ANRC-HE7^T shared characteristics with most type strains within the genus. Its respiratory quinone was MK-6. The major fatty acids were iso-C_15:0, summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), and anteiso-C_15:0. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids, four unidentified phospholipids, and five unidentified glycolipids. The DNA G + C content of strain ANRC-HE7^T was 40.1%. Based on the results of the biochemical, phylogenetic, and chemotaxonomic analyses, strain ANRC-HE7^T is suggested to represent a novel species of the genus Maribacter, for which the name Maribacter aquimaris sp. nov. is proposed. The type strain is ANRC-HE7^T (= MCCC 1K03787^T = KCTC 72532^T).

Aggregatimonas sangjinii gen. nov., sp. nov., a novel silver nanoparticle synthesizing bacterium belonging to the family Flavobacteriaceae

Microbially synthesized nanoparticles has received increasing attentions owing to the broad applications in biology and medicine. In this study, we report a novel bacterium that biologically generates silver nanoparticles (AgNPs). This bacterium, designated strain F202Z8^T, was isolated from a rusty iron plate found in the intertidal region of Taean, South Korea. The morphological, biochemical and molecular characteristics predicted that strain F202Z8^T belongs to the family Flavobacteriaceae. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain F202Z8^T forms a distinct lineage with closely related genera Maribacter, Pelagihabitans, Pseudozobellia, Zobellia, Pricia, and Costertonia and showed the highest similarity to Maribacter aestuarii GY20^T (94.5%). The digital DNA-DNA hybridization and average nucleotide identity values calculated from the whole genome-sequence comparison between strain F202Z8^T and other members of the family Flavobacteriaceae were in the ranges of 12.7%-16.9% and 70.3%-74.4%, respectively, suggesting that strain F202Z8^T represented a novel genus. The complete genome sequence of strain F202Z8^T is 4,723,614 bp, with 43.26% G + C content. Based on the COG, GO, KEGG, NR, and Swiss-Prot databases, the genomic analysis of F202Z8^T revealed the presence of 17 putative genes responsible for the synthesis of AgNPs. Our polyphasic taxonomic results suggested that this strain represents a novel species of a novel genus in the family Flavobacteriaceae, for which the name Aggregatimonas sangjinii gen. nov., sp. nov. is proposed. The type strain of Aggregatimonas sangjinii is F202Z8^T (= KCCM 43411^T = LMG 31494^T). Overall, our data provide fundamental information to potentially utilize this novel bacterium for synthesis of nanoparticles.

Bioremediation of Petroleum Hydrocarbons in Seawater: Prospects of Using Lyophilized Native Hydrocarbon-Degrading Bacteria

This work aimed to develop a bioremediation product of lyophilized native bacteria to respond to marine oil spills. Three oil-degrading bacterial strains (two strains of Rhodococcus erythropolis and one Pseudomonas sp.), isolated from the NW Portuguese coast, were selected for lyophilization after biomass growth optimization (tested with alternative carbon sources). Results indicated that the bacterial strains remained viable after the lyophilization process, without losing their biodegradation potential. The biomass/petroleum ratio was optimized, and the bioremediation efficiency of the lyophilized bacterial consortium was tested in microcosms with natural seawater and petroleum. An acceleration of the natural oil degradation process was observed, with an increased abundance of oil-degraders after 24 h, an emulsion of the oil/water layer after 7 days, and an increased removal of total petroleum hydrocarbons (47%) after 15 days. This study provides an insight into the formulation and optimization of lyophilized bacterial agents for application in autochthonous oil bioremediation.

Maribacter hydrothermalis sp. nov., Isolated from Shallow-Sea Hydrothermal Systems Off Kueishantao Island

A Gram-stain-negative, strictly aerobic, yellow-pigmented bacterial strain, designated as T28^T, was isolated from seawater of the shallow-sea hydrothermal system, Kueishantao Islet, Taiwan, China. Cells were oxidase-negative and catalase-positive rods without gliding motility. Growth was observed at 10-40 °C (optimum, 30 °C), at pH 5.0-8.0 (optimum, pH 6.0) and in the presence of 0-5% (w/v) NaCl (optimum, 2.5%). Strain T28^T contained menaquinone 6 as the only isoprenoid quinone. The main cellular fatty acids were iso-C_15:0, iso-C_15:1 G, and iso-C_17:03-OH, summed feature 3 (C_16:1ω7c/ω6c). Polar lipids contain diphosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids, six unidentified lipids, an unidentified aminolipid, and one unidentified aminophospholipids. The genomic DNA G + C content was 34.4 mol%. The 16S rRNA gene sequence of strain T28^T shared highest similarity with Maribacter arcticus (97.7%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain T28^T belongs to the genus Maribacter. On the basis of phylogenetic data and several distinct phenotypic characteristics, strain T28^T represents a novel species, for which the name Maribacter hydrothermalis sp. nov. is proposed. The type strain is T28^T (=CGMCC 1.15788^T = JCM 31510^T).

Organohalide-Respiring Bacteria at the Heart of Anaerobic Metabolism in Arctic Wet Tundra Soils

Recent work revealed an active biological chlorine cycle in coastal Arctic tundra of northern Alaska. This raised the question of whether chlorine cycling was restricted to coastal areas or if these processes extended to inland tundra. The anaerobic process of organohalide respiration, carried out by specialized bacteria like Dehalococcoides, consumes hydrogen gas and acetate using halogenated organic compounds as terminal electron acceptors, potentially competing with methanogens that produce the greenhouse gas methane. We measured microbial community composition and soil chemistry along an ∼262-km coastal-inland transect to test for the potential of organohalide respiration across the Arctic Coastal Plain and studied the microbial community associated with Dehalococcoides to explore the ecology of this group and its potential to impact C cycling in the Arctic. Concentrations of brominated organic compounds declined sharply with distance from the coast, but the decrease in organic chlorine pools was more subtle. The relative abundances of Dehalococcoides were similar across the transect, except for being lower at the most inland site. Dehalococcoides correlated with other strictly anaerobic genera, plus some facultative ones, that had the genetic potential to provide essential resources (hydrogen, acetate, corrinoids, or organic chlorine). This community included iron reducers, sulfate reducers, syntrophic bacteria, acetogens, and methanogens, some of which might also compete with Dehalococcoides for hydrogen and acetate. Throughout the Arctic Coastal Plain, Dehalococcoides is associated with the dominant anaerobes that control fluxes of hydrogen, acetate, methane, and carbon dioxide. Depending on seasonal electron acceptor availability, organohalide-respiring bacteria could impact carbon cycling in Arctic wet tundra soils.IMPORTANCE Once considered relevant only in contaminated sites, it is now recognized that biological chlorine cycling is widespread in natural environments. However, linkages between chlorine cycling and other ecosystem processes are not well established. Species in the genus Dehalococcoides are highly specialized, using hydrogen, acetate, vitamin B₁₂-like compounds, and organic chlorine produced by the surrounding community. We studied which neighbors might produce these essential resources for Dehalococcoides species. We found that Dehalococcoides species are ubiquitous across the Arctic Coastal Plain and are closely associated with a network of microbes that produce or consume hydrogen or acetate, including the most abundant anaerobic bacteria and methanogenic archaea. We also found organic chlorine and microbes that can produce these compounds throughout the study area. Therefore, Dehalococcoides could control the balance between carbon dioxide and methane (a more potent greenhouse gas) when suitable organic chlorine compounds are available to drive hydrogen and acetate uptake.

Maribacter algarum sp. nov., a new member of the family Flavobacteriaceae isolated from the red alga Gelidium amansii

A Gram-stain-negative, rod-shaped (0.2–0.3×1.0-2.4 µm), catalase-positive, oxidase-negative and non-motile bacterium, designated strain RZ26T, was isolated from the marine red algae collected from the coast of Weihai, PR China. Growth of strain RZ26T occurred at 15–33 °C (optimum, 25–28 °C), pH 6.0–9.5 (optimum, pH 7.0–7.5) and 0.5–5.0 % (w/v) NaCl (optimum, 2.0–3.0 %). Resuls of phylogenetic analysis based on 16S rRNA gene sequences showed that strain RZ26T was most closely related to Maribacter spongiicola DSM 25233T (96.2 % sequence similarity), followed by Maribacter forsetii DSM 18668T (96.1 %) and Maribacter vaceletii DSM 25230T (95.4 %). The average nucleotide identity and the average amino acid identity values between strain RZ26T and M. sedimenticola KCTC 12966T, M. spongiicola DSM 25233T, M. vaceletii DSM 25230T and M. forsetii DSM 18668T were 75.6, 76.2, 76.0, 76.7, 64.3, 63.9, 68.6 and 68.0 %, respectively. The digital DNA–DNAhybridization values based on the draft genomes between strain RZ26T and M. sedimenticola KCTC 12966T, M. spongiicola DSM 25233T and M. vaceletii DSM 25230T were 38.0, 35.1 and 37.1 %, respectively. The major fatty acids in strain RZ26T were iso-C17 : 0 3-OH, iso-C15 : 0 and C16 : 1  ω7c/C16 : 1  ω6c. The major respiratory quinone was MK-6. The dominant polar lipid was phosphatidylethanolamine. The DNA G+C content was 38.0 mol%. Phylogenetic analysis shows strain RZ26T fell within a clade comprising species of the genus Maribacter . Polyphasic taxonomy indicates that the isolate represents a novel species of the genus Maribacter , for which the name Maribacter algarum sp. nov. is proposed, with type strain RZ26T (=KCTC 62992T=MCCC 1H00362T).

Maribacter algicola sp. nov., isolated from a marine red alga, Porphyridium marinum, and transfer of Maripseudobacter aurantiacus Chen et al. 2017 to the genus Maribacter as Maribacter aurantiacus comb. nov

A Gram-stain-negative, strictly aerobic and moderately halophilic bacterial strain, designated strain PoM-212^T, was isolated from a marine alga, Porphyridium marinum, in the Republic of Korea. Cells were catalase- and oxidase-positive rods with gliding motility without flagellum. Growth was observed at 20-40 °C (optimum, 30 °C) and pH 5.0-8.5 (pH 5.0-5.5) and in the presence of 0.5-5 % (w/v) NaCl (2-3 %). Strain PoM-212^T contained iso-C_15 : 1, iso-C_15 : 0, iso-C_17 : 0 3-OH and summed feature 3 (comprising C_16 : 1ω7c and/or C_16 : 1ω6c) as major fatty acids and menaquinone-6 as the sole isoprenoid quinone. Phosphatidylethanolamine, three unidentified aminolipids and two unidentified polar lipids were detected as major polar lipids. The G+C content of the genomic DNA was 41.0 mol%. Strain PoM-212^T was most closely related to Maribacter lutimaris KJ4^T, Maripseudobacter aurantiacus CDA4^T and Maribacter flavus C3^T with 97.2, 97.2 and 97.0 % 16S rRNA gene sequence similarities, respectively, and it formed a distinct phylogenetic lineage from them within the genus Maribacter. Maripseudobacter aurantiacus formed a close phylogenetic lineage with Maribacter flavus with 99.7 % 16S rRNA gene sequence similarity, but their digital DNA-DNA hybridization value was 67.4 %. On the basis of its phenotypic, chemotaxonomic and molecular properties, strain PoM-212^T represents a novel species of the genus Maribacter, for which the name Maribacter algicola sp. nov. is proposed. The type strain is PoM-212^T (=KACC 19789^T=JCM 32941^T). The transfer of Maripseudobacter aurantiacus to the genus Maribacter as Maribacter aurantiacus comb. nov. is also proposed (type strain CDA4^T=KCTC 52409^T=MCCC 1K03210^T).

Analysis of 1,000 Type-Strain Genomes Improves Taxonomic Classification of Bacteroidetes

Although considerable progress has been made in recent years regarding the classification of bacteria assigned to the phylum Bacteroidetes, there remains a need to further clarify taxonomic relationships within a diverse assemblage that includes organisms of clinical, piscicultural, and ecological importance. Bacteroidetes classification has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees and a limited number of phenotypic features. Here, draft genome sequences of a greatly enlarged collection of genomes of more than 1,000 Bacteroidetes and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa proposed long ago such as Bacteroides, Cytophaga, and Flavobacterium but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which can be considered valuable taxonomic markers. We detected many incongruities when comparing the results of the present study with existing classifications, which appear to be caused by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. The few significant incongruities found between 16S rRNA gene and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences and the impediment in using ordinary bootstrapping in phylogenomic studies, particularly when combined with too narrow gene selections. While a significant degree of phylogenetic conservation was detected in all phenotypic characters investigated, the overall fit to the tree varied considerably, which is one of the probable causes of misclassifications in the past, much like the use of plesiomorphic character states as diagnostic features.

Maribacter litoralis sp. nov. a marine bacterium isolated from seashore

A novel Gram-stain-negative, moderately halophilic and aerobic bacterium, designated strain SDRB-Phe2^T, was isolated from coastal sediment of the yellow sea in Sindu-ri, Republic of Korea. Cells were oxidase-positive, catalase-positive, rod-shaped and surrounded by a capsule with gliding motility. Colonies were yellow-coloured, circular, pulvinate with entire margins. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SDRB-Phe2^T formed a distinct lineage within the genus Maribacter of the family Flavobacteriaceae. Stain SDRB-Phe2^T exhibited 16S rRNA gene sequence similarity values of 97.1-98.9 % to the type strains of Maribacterstanieri, Maribacterspongiicola, Maribacter forsetii, Maribacter dokdonensis, Maribacter aquivivus, Maribactercaenipelagi, Maribacterlitorisediminis, Maribactersedimenticola, Maribacterulvicola, Maribacter confluentis and Maribacter orientalis, and of 94.8-96.7 % to the type strains of the other species of the genus Maribacter. Strain SDRB-Phe2^T contained MK-6 as the predominant respiratory quinone and iso-C15 : 1 G, iso-C15 : 0 and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) as the major fatty acids. The polar lipids of strain SDRB-Phe2^T were phosphatidylethanolamine, one unidentified amino lipid and two unidentified lipids. The DNA G+C content was 36.2 mol%. DNA-DNA relatedness values of strain SDRB-Phe2^T to the type strains of the 11 phylogenetically related species of the genus Maribacter were 21.9-38.6 %. On the basis of the phenotypic features, phylogenetic and DNA-DNA hybridization analyses presented here, strain SDRB-Phe2^T (=JCM 32373^T=KCTC 62273^T=DSM 106042^T) represents a novel species of the genus Maribacter, for which the name Maribacterlitoralis sp. nov. is proposed.

Maribacter maritimus sp. nov., isolated from seawater

A novel Gram-stain-negative, motile by gliding and straight rod-shaped bacterial strain, designated HMF3635^T, was isolated from seawater of the East Sea, Republic of Korea. Strain HMF3635^T grew optimally on marine agar at 30 °C, pH 7.0-8.0 and 2.0 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain HMF3635^T belonged to the genus Maribacter and was most closely related to Maribacter arenosus CAU 1321^T (96.4 % sequence similarity) and Maribacter polysiphoniae KMM 6151^T (96.0 %). The major fatty acids were iso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The only respiratory quinone was menaquinone 6. The major polar lipids were phosphatidylethanolamine, four unidentified aminolipids, one unidentified phospholipid and three unidentified polar lipids. The DNA G+C content was 38.7 mol%. On the basis of the evidence presented in this study, strain HMF3635^T represents a novel species of the genus Maribacter, for which the name Maribacter maritimus sp. nov. is proposed. The type strain of the species is strain HMF3635^T (=KCTC 52399^T=NBRC 112671^T).

Maribacter marinus sp. nov. isolated from a deep-sea seamount

A Gram-stain negative, rod-shaped, aerobic strain, designated YC973^T, was isolated from a seamount near the Yap Trench in the tropical western Pacific. Phylogenetic analysis based on its 16S rRNA gene sequence showed that strain YC973^T is related to the genus Maribacter and has high 16S rRNA gene sequence similarity to Maribacter orientalis KMM 3947^T (97.6%). The predominant cellular fatty acids were iso-C_15:0, iso-C_15:1 G and an unidentified fatty acid of equivalent chain-length 13.565. The polar lipid profile contained phosphatidylethanolamine and five unidentified lipids. The genomic DNA G+C content of strain YC973^T was 36.1 mol%. On the basis of the evidence presented in this study, strain YC973^T represents a novel species of the genus Maribacter, for which we propose the name Maribacter marinus sp. nov. (type strain YC973^T = KACC 19025^T = CGMCC 1.16328^T).

Maribacter pelagius sp. nov., isolated from seawater

A Gram-stain-negative, gliding, non-endospore-forming and slightly halophilic bacterial strain, CBA3204^T, was isolated from seawater and characterized by polyphasic taxonomic analysis. Phylogenetic analysis based on 16S rRNA sequences revealed that strain CBA3204^T formed a distinct lineage within the family Flavobacteriaceae. The 16S rRNA sequences of strain CBA3204^T had a sequence similarity level of 96.96 % to Maribacter arcticus KOPRI 20941^T as the nearest phylogenetic neighbour. The strain grew optimally at 25-30 °C and in the presence of 2-4 % (w/v) NaCl. The dominant menaquinone was MK-6 and the major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G. The DNA G+C content was 35.1 mol%. There were some differences in phenotypic properties among strain CBA3204^T and other Maribacter species. On the basis of polyphasic analysis containing phenotypic, phylogenetic and chemotaxonomic data, strain CBA3204^T (=KACC 17671^T=JCM 19533^T) is proposed as a novel species Maribacter pelagius sp. nov.

Aurantibacter crassamenti gen. nov., sp. nov., a bacterium isolated from marine sediment

A Gram-stain-negative, strictly aerobic, orange-colored, rod-shaped, chemoheterotrophic bacterium, designated HG732^T, was isolated from marine sediment in Japan. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the novel marine strain was affiliated with the family Flavobacteriaceae of the phylum Bacteroidetes and that it shared the highest (94.1 %) sequence similarity with Kriegella aquimaris KMM 3665^T. The strain could be differentiated phenotypically from related members of the family Flavobacteriaceae. Major fatty acids of strain HG732^T were iso-C15:1 G, iso-C15:0 and iso-C17:0 3-OH. The polar lipid profile consisted of phosphatidylglycerol, three unidentidied aminolipids and two unidentified lipids. The DNA G+C content of the strain was determined to be 35.2 mol%, and the major respiratory quinone was identified as menaquinone 6 (MK-6). From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus in the family Flavobacteriaceae, for which the name Aurantibacter crassamenti gen. nov., sp. nov. is proposed. The type strain of A. crassamenti gen. nov., sp. nov. is HG732^T (= KCTC 52207^T = NBRC 112211^T).

Maribacter arenosus sp. nov., isolated from marine sediment

A Gram-staining-negative, non-spore-forming, non-gliding, aerobic bacterial strain, designated CAU 1321T was isolated from marine sediment in Incheon, South Korea. The strain's taxonomic position was investigated using a polyphasic approach. CAU 1321T grew optimally at 30 °C and at pH 8 in the presence of 1 % (w/v) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that CAU 1321T represented a member of the genus Maribacter, closely related to Maribacter polysiphoniae KCTC 22021T (similarity 98.0 %). The strain contained MK-6 as the predominant menaquinone and iso-C15 : 0, iso-C17 : 0 3-OH, and iso-C15 : 1 G as the major fatty acids. The polar lipids of CAU 1321T consisted of phosphatidylethanolamine, one unidentified aminoglycolipid, five unidentified aminolipids, two unidentified aminophospholipids, two unidentified glycolipids and three unidentified lipids. The DNA G+C content was 40.6 mol% and the level of DNA-DNA relatedness between CAU 1321T and the most closely related strain, M. polysiphoniae KCTC 22021T was 25.2 %. On the basis of phenotypic and chemotaxonomic properties, and phylogenetic inference, CAU 1321T is considered to represent a novel species of the genus Maribacter, for which the name Maribacter arenosus sp. nov. is proposed. The type strain is CAU 1321T (=KCTC 52191T=NBRC 111990T).

Seohaeicola zhoushanensis sp. nov., isolated from seawater

A novel, Gram-stain-negative, motile, facultatively anaerobic bacterium, designated strain NF48T, was isolated from surface seawater around Zhoushan Islands. Cells were rod-shaped (1.1-3.9×0.5-0.9 µm). Strain NF48T was able to grow at 10-40 °C (optimum 30 °C), at pH 5.5-9.0 (optimum 6.5-8.0) and with 0.5-7.0 % (w/v) NaCl (optimum 2.0 %). The genomic DNA G+C content was 65.5 mol%. Chemotaxonomic analysis showed that the main isoprenoid quinone was Q-10 and the major fatty acids were C18 : 1ω7c and C16 : 0. The major polar lipids of strain NF48T were phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NF48T belonged to the genus Seohaeicola with similarity values of 95.5-97.2 % to members of this genus, and was most closely related to Seohaeicola nanhaiensis SS011A0-7#2-2T (97.2 %). On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, strain NF48T is suggested to represent a novel species of the genus Seohaeicola, for which the name Seohaeicola zhoushanensis sp. nov. is proposed. The type strain is NF48T (=MCCC 1K01157T=KCTC 42650T).

Maribacter lutimaris sp. nov., isolated from marine sediment

A Gram-staining-negative, moderately halophilic and strictly aerobic bacterium, designated strain KJ4T, was isolated from marine sediment at Gangjin in South Korea. Cells were catalase- and oxidase-positive long rods with gliding motility. Growth of strain KJ4T was observed at 4-37 °C (optimum, 15-25 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.5) and in the presence of 1.0-7.0% (w/v) NaCl (optimum, 2.0-5.0%). Menaquinone 6 (MK-6) was the only isoprenoid quinone detected and iso-C15:0, iso-C17:0 3-OH, iso-C15:1 G and summed feature 3 (comprising C16:1ω7c and/or C16:1ω6c) were the major cellular fatty acids. The polar lipids of strain KJ4T consisted of phosphatidylethanolamine, an unidentified aminophospholipid and five unidentified lipids. The G+C content of the genomic DNA was 38.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain KJ4T formed a distinct phylogenetic lineage within the genus Maribacter. Strain KJ4T was most closely related to Maribacter orientalis KMM 3947T with 97.4% 16S rRNA gene sequence similarity. On the basis of phenotypic, chemotaxonomic and molecular features, strain KJ4T clearly represents a novel species of the genus Maribacter, for which the name Maribacter lutimaris sp. nov. is proposed. The type strain is KJ4T (=KACC 16438T=JCM 31154T).

Genome sequence of facultatively anaerobic marine bacterium Maribacter thermophilus strain HT7-2(T)

Maribacter thermophilus strain HT7-2(T), isolated from Ulva prolifera collected from the intertidal zone of Qingdao sea area, China. To date, M. thermophilus strain HT7-2(T) is the only one which has been found that has a relatively higher optimum temperature compared to other Maribacter species and it is also the first strain to be described that is facultatively anaerobic while other identified strains within genus Maribacter are strictly aerobic. Meanwhile, M. thermophilus strain HT7-2(T) harbors several coding genes related to heavy metal resistance and to antibiotics, which increase the robustness of the strain. Here, we report the genome sequence and annotation of M. thermophilus strain HT7-2(T), which comprises 4,050,606 bp with G+C content of 38.93%. A total of 3585 protein coding genes, 41 tRNAs and 6rRNAs were obtained. The genome annotation may provide basic information on some special traits and pathways in this strain.

Maribacter confluentis sp. nov., isolated from the junction between the ocean and a freshwater spring

A Gram-stain-negative, aerobic, non-spore-forming, non-flagellated, non-gliding and rod-shaped bacterial strain, SSK2-2(T), was isolated from the place where the ocean and a freshwater spring meet at Jeju island, South Korea. Strain SSK2-2(T) grew optimally at 30 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0% (w/v) NaCl. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain SSK2-2(T) fell within the clade comprising the type strains of species of the genus Maribacter, joining the type strain of Maribacter sedimenticola with which it shared 99.4% similarity. Sequence similarities to the type strains of other Maribacter species were 94.6-98.2%. Strain SSK2-2(T) contained MK-6 as the predominant menaquinone and iso-C17 : 0 3-OH, iso-C15 : 0, iso-C15 : 1 G, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 9 (iso-C17 : 1ω9c and/or 10-methyl C16 : 0) as the major fatty acids. The major polar lipids of strain SSK2-2(T) were phosphatidylethanolamine and one unidentified lipid. The DNA G+C content of strain SSK2-2(T) was 38.2 mol% and mean levels of DNA-DNA relatedness with the type strains of four phylogenetically related species of the genus Maribacter were 11-24%. Differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain SSK2-2(T) is separate from other Maribacter species. On the basis of the data presented, strain SSK2-2(T) is considered to represent a novel species of the genus Maribacter, for which the name Maribacter confluentis sp. nov. is proposed. The type strain is SSK2-2(T) ( = KCTC 42604(T) = CECT 8869(T)).

Maribacter spongiicola sp. nov. and Maribacter vaceletii sp. nov., isolated from marine sponges, and emended description of the genus Maribacter

Two Gram-stain-negative, rod-shaped, orange, catalase- and oxidase-positive, non-motile bacteria, designated W13M1A(T) and W15M10(T), were isolated from the marine sponges Suberites carnosus and Leucosolenia sp., respectively, which were sampled from Lough Hyne, Co. Cork, Ireland. Analysis of the 16S rRNA gene sequences of these isolates revealed that they are members of the genus Maribacter, in the family Flavobacteriaceae of the phylum Bacteroidetes. The type strain most closely related to strain W13M1A(T) is Maribacter forsetii DSM 18668(T) with a gene sequence similarity of 96.5%. The closest related type strain to strain W15M10(T) is Maribacter orientalis DSM 16471(T) with a gene sequence similarity of 98.3%. Phylogenetic inference and phenotypic data combined indicate that the isolates represent two novel species of the genus Maribacter, for which the names Maribacter spongiicola sp. nov. with type strain W15M10(T) ( = NCIMB 14725(T) = DSM 25233(T)) and Maribacter vaceletii sp. nov. with type strain W13M1A(T) ( = NCIMB 14724(T) = DSM 25230(T)), are proposed.