Methanooceanicella nereidis gen. nov., sp. nov., the first oceanic Methanocellaceae methanogen, isolated from potential methane hydrate bearing area offshore southwestern Taiwan.

A novel mesophilic, hydrogenotrophic methanogen, strain CWC-04T, was obtained from a sediment sample extracted from a gravity core retrieved at station 22 within the KP-9 area off the southwestern coast of Taiwan during the ORIII-1368 cruise in 2009. Cells of strain CWC-04T were rod-shaped, 1.4-2.9 µm long by 0.5-0.6 µm wide, and occurred singly. Strain CWC-04Tutilized formate, H2/CO2, 2-propanol/CO2 or 2-butanol/CO2 as catabolic substrates. The optimal growth conditions were 42 °C, 0.17 M NaCl and pH 5.35. The genomic DNA G+C content calculated from the genome sequence of strain CWC-04T was 46.19 mol%. Phylogenetic analysis of 16S rRNA gene revealed that strain CWC-04T is affiliated with the genus Methanocella. The 16S rRNA gene sequences similarities within strains Methanocella arvoryzae MRE50T, Methanocella paludicola SANAET and Methanocella conradii HZ254T were 93.7, 93.0 and 91.3 %, respectively. In addition, the optical density of CWC-04T culture dropped abruptly upon entering the late-log growth phase, with virus-like particles (150 nm in diameter) being observed on and around the cells. This observation suggests that strain CWC-04T harbours a lytic virus. Based on these phenotypic, phylogenetic and genomic results, we propose that strain CWC-04T represents a novel species of a novel genus in the family Methanocellaceae, for which the name Methanooceanicella nereidis gen. nov., sp. nov. is proposed. The type strain is CWC-04T (=BCRC AR10050T=NBRC 113165T).

Microbaculum marinisediminis sp. nov., isolated from marine sediment.

A novel Gram-stain-negative and facultatively anaerobic bacterium, designated A6E488T, was isolated from intertidal sediment collected from Xiaoshi Island, Weihai, PR China (122° 1' E 37° 31' N). Cells of strain A6E488T were rod-shaped with widths of 0.3-0.4 µm and lengths of 1.1-1.8 µm. The optimal growth conditions were determined to be in 1 % (w/v) NaCl, at 37 °C, and at pH 7.0. The predominant fatty acids (≥10 %) were C19 : 0 cyclo ω8c (59.7 %) and summed feature 8 (13.8 %, C18 : 1 ω7c and/or C18 : 1 ω6c). The sole isoprenoid quinone was Q-10. Oxidase activity was negative but catalase activity was positive. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid, one unidentified glycolipid, and one unidentified lipid. Based on phylogenetic analysis of 16S rRNA gene sequences, strain A6E488T showed the highest sequence similarity to Microbaculum marinum MCCC 1K03192T (97.6 %). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain A6E488T and M. marinum MCCC 1K03192T did not exceed 78 and 22 %, respectively. These values are below the recommended thresholds of 95 % (ANI) and 70 % (dDDH) for prokaryotic species delineation. On the basis of gene annotation, it was observed that strain A6E488T possesses the capability for thiosulphate oxidation, suggesting that this strain might be important in the sulphur cycle. Based on the results of phenotypic, genotypic, and chemical characterization, strain A6E488T is considered to represent a novel species of the genus Microbaculum, for which the name Microbaculum marinisediminis sp. nov. is proposed. The type strain is A6E488T (=KCTC 92197T=MCCC 1H00516T).

Marinimicrococcus flavescens gen. nov., sp. nov., a new member of the family Geminicoccaceae, isolated from a marine sediment of the South China Sea.

A Gram-stain-negative, catalase-positive and oxidase-positive, nonmotile, aerobic, light yellow, spherical-shaped bacterial strain with no flagella, designated strain YIM 152171T, was isolated from sediment of the South China Sea. Colonies were smooth and convex, light yellow and circular, and 1.0-1.5×1.0-1.5 µm in cell diameter after 7 days of incubation at 28°C on YIM38 media supplemented with sea salt. Colonies could grow at 20-45°C (optimum 28-35°C) and pH 6.0-11.0 (optimum, pH 7.0-9.0), and they could proliferate in the salinity range of 0-6.0 % (w/v) NaCl. The major cellular fatty acids were summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c), C18 : 1 ω7c 11-methyl, C16 : 0, C16 : 1 ω11c, C16 : 1 ω5c, C17 : 1 ω6c and C18 : 1 ω5c. The respiratory quinone was ubiquinone 10, and the polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol mannoside, one unidentified phospholipid and one unidentified aminolipid. Phylogenetic analyses based on the 16S rRNA gene sequences placed strain YIM 152171T within the order Rhodospirillales in a distinct lineage that also included the genus Geminicoccus. The 16S rRNA gene sequence similarities of YIM 152171T to those of Arboricoccus pini, Geminicoccus roseus and Constrictibacter antarcticus were 92.17, 89.25 and 88.91 %, respectively. The assembled draft genome of strain YIM 152171T had 136 contigs with an N50 value of 134704 nt, a total length of 3 001 346 bp and a G+C content of 70.27 mol%. The phylogenetic, phenotypic and chemotaxonomic data showed that strain YIM 152171T (=MCCC 1K08488T=KCTC 92884T) represents a type of novel species and genus for which we propose the name Marinimicrococcus gen. nov., sp. nov.

Phytohabitans maris sp. nov., isolated from marine sediment.

A novel actinobacterium, strain ZYX-F-186T, was isolated from marine sediment sampled on Yongxing Island, Hainan Province, PR China. Based on the results of 16S rRNA gene sequence analysis, strain ZYX-F-186T belongs to the genus Phytohabitans, with high similarity to Phytohabitans kaempferiae KK1-3T (98.3 %), Phytohabitans rumicis K11-0047T (98.1 %), Phytohabitans flavus K09-0627T (98.1 %), Phytohabitans houttuyneae K11-0057T (97.9 %), Phytohabitans suffuscus K07-0523T (97.7 %), and Phytohabitans aurantiacus RD004123T (97.7 %). Phylogenetic analysis of 16S rRNA gene sequences showed that the strain formed a single subclade in the genus Phytohabitans. The novel isolate contained meso-diaminopimelic acid, d-glutamic acid, glycine, d-alanine, and l-lysine in the cell wall. The whole-cell sugars were xylose, arabinose, ribose, and rhamnose. The predominant menaquinones were MK-9(H8), MK-9(H6), and MK-9(H4). The characteristic phospholipids were phosphatidylethanolamine, phosphatidylinositol, phosphatidylmethylethanolamine, phosphatidylglycerol, and an unknown phospholipid. The major fatty acids (>5 %) were iso-C16 : 0, anteiso-C17 : 0, and iso-C18 : 0. Genome sequencing showed a DNA G+C content of 71.9 mol%. Low average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values demonstrated that strain ZYX-F-186T could be readily distinguished from its closely related species. Based on its phylogenetic, chemotaxonomic, and physiological characteristics, strain ZYX-F-186T represents a novel species of the genus Phytohabitans, for which the name Phytohabitans maris sp. nov. is proposed. The type strain is ZYX-F-186T (=CGMCC 4.8025T=CCTCC AA 2023025T=JCM 36507T).

Actomonas aquatica gen. nov., sp. nov., a marine lineage in the phylum Verrucomicrobiota with genetic potential for carbon and nitrogen fixation.

A novel bacterial strain, designated WL0086T, was isolated from a marine sediment sample collected in Lianyungang city, Jiangsu province, PR China. This strain showed the highest 16S rRNA gene sequence similarity to Geminisphaera colitermitum TAV2T (92.7 %) of the family Opitutaceae, and all the unclassified cultured and uncultured isolates with similarities >95 % were from marine environments. Cells were Gram-stain-negative, aerobic, non-motile cocci with a size of 0.6-0.8 µm in diameter. Strain WL0086T was positive for both oxidase and catalase, and grew at 20-37 °C (optimum, 28 °C), with 1.5-11.0 % NaCl (w/v; optimum, 2.5-4.0 %) and at pH 5.0-9.0 (optimum, pH 7.0). The major polar lipid profile of strain WL0086T consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylcholine. The major isoprenoid quinone was menaquinone-7 and the predominant fatty acids were iso-C14 : 0, anteiso-C15 : 0, C16 : 0 and C16 : 1 ω9c. The complete genome consisted of a chromosome with 6 109 182 bp. The G+C content of genomic DNA was 64.0%. Results of phylogenomic analysis based on the 16S rRNA gene sequence and the whole genome suggested that strain WL0086T formed a distinct clade closely neighbouring the members of the family Opitutaceae. On the basis of phylogenetic, phenotypic, and chemotaxonomic evidences, strain WL0086T should represent a novel genus of the family Opitutaceae, for which the name Actomonas aquatica gen. nov., sp. nov. is proposed. The type strain is WL0086T (=MCCC 1K05844T=JCM 34677T=GDMCC 1.2411T).

Impact of Concurrent aerobic-anaerobic Methanotrophy on Methane Emission from Marine Sediments in Gas Hydrate Area.

Microbial methane oxidation has a significant impact on the methane flux from marine gas hydrate areas. However, the environmental fate of methane remains poorly constrained. We quantified the relative contributions of aerobic and anaerobic methanotrophs to methane consumption in sediments of the gas hydrate-bearing Sakata Knoll, Japan, by in situ geochemical and microbiological analyses coupled with 13C-tracer incubation experiments. The anaerobic ANME-1 and ANME-2 species contributed to the oxidation of 33.2 and 1.4% methane fluxes at 0-10 and 10-22 cm below the seafloor (bsf), respectively. Although the aerobic Methylococcaceae species consumed only 0.9% methane flux in the oxygen depleted 0.0-0.5 cmbsf zone, their metabolic activity was sustained down to 6 cmbsf (based on rRNA and lipid biosyntheses), increasing their contribution to 10.3%. Our study emphasizes that the co-occurrence of aerobic and anaerobic methanotrophy at the redox transition zone is an important determinant of methane flux.

Universal occurrence of organophosphate tri-esters and di-esters in marine sediments: Evidence from the Okinawa Trough in the East China Sea.

Despite numerous data on organophosphate tri-esters (tri-OPEs) in the environment, literatures on organophosphate di-esters (di-OPEs) in field environment, especially marine sediments remain scarce. This study addresses this gap by analyzing 35 abyssal sediment samples from the middle Okinawa Trough in the East China Sea. A total of 25 tri-OPEs and 10 di-OPEs were determined, but 13 tri-OPEs and 2 di-OPEs were nondetectable in any of these sediment samples. The concentrations of ∑12tri-OPE and ∑8di-OPE were 0.108-32.2 ng/g (median 1.11 ng/g) and 0.548-15.0 ng/g (median 2.74 ng/g). Chlorinated (Cl) tri-OPEs were the dominant tri-esters, accounting for 47.5 % of total tri-OPEs on average, whereas chlorinated di-OPEs represented only 19.2 % of total di-OPEs. This discrepancy between the relatively higher percentage of Cl-tri-OPEs and lower abundance of Cl-di-OPEs may be ascribed to the stronger environmental persistence of chlorinated tri-OPEs. Source assessment suggested that di-OPEs were primarily originated from the degradation of tri-OPEs rather than industrial production. Long range waterborne transport facilitated by oceanic currents was an important input pathway for OPEs in sediments from the Okinawa Trough. These findings enhance the understanding of the sources and transport of OPEs in marine sediments, particularly in the Okinawa Trough.

Oceanimonas pelagia sp. nov., a novel biosurfactant-producing and plastic-degrading potential bacterium isolated from marine coastal sediment.

A marine bacterial strain, named NTOU-MSR1T, was isolated from marine sediment of northern coast of Taiwan. This bacterium was Gram-stain-negative, aerobic, and motile, with a single flagellum. Its rod-shaped cells measured approximately 0.5-0.6 µm in width and 1.8-2.0 µm in length. NTOU-MSR1T grew at temperatures ranging from 10 to 45 °C, optimally at 30 °C. The pH range for growth was 7.0-10.0, with optimal growth at pH 7.0-8.0. It tolerated NaCl concentrations up to 12%. The cell membrane predominantly contained fatty acids such C16:1ω7c, C18:1ω7c, and C16:0. The overall genome relatedness indices indicated that strain NTOU-MSR1T had an average nucleotide identity (ANI) of 87.88% and a digital DNA-DNA hybridization (dDDH) value of 35.40% compared to its closest related species, O. marisflavi 102-Na3T. These values fell below the 95% and 70% threshold for species delineation, respectively. These findings suggested that the strain NTOU-MSR1T was a new member of the Oceanimonas genus. Its genomic DNA had a G + C content of 61.0 mol%. Genomic analysis revealed genes associated with the catechol branch of ß- ketoadipate pathway for degrading polycyclic aromatic hydrocarbons, resistance to heavy metal, biosynthesis of polyhydroxybutyrate and the production of glycoside hydrolases (GH19, GH23, and GH103) for chitin and glycan digestion. Additionally, NTOU-MSR1T was capable of synthesizing biosurfactants and potentially degrading plastic. The proposed name for this new species is Oceanimonas pelagia, with the type strain designated as NTOU-MSR1T (= BCRC 81403T = JCM 36023T).

Bioprospecting of extremophilic perchlorate-reducing bacteria: report of promising Bacillus spp. isolated from sediments of the bay of Cartagena, Colombia.

Three extremophile bacterial strains (BBCOL-009, BBCOL-014 and BBCOL-015), capable of degrading high concentrations of perchlorate at a range of pH (6.5 to 10.0), were isolated from Colombian Caribbean Coast sediments. Morphological features included Gram negative strain bacilli with sizes averaged of 1.75 × 0.95, 2.32 × 0.65 and 3.08 × 0.70 µm, respectively. The reported strains tolerate a wide range of pH (6.5 to 10.0); concentrations of NaCl (3.5 to 7.5% w/v) and KClO4- (250 to 10000 mg/L), reduction of KClO4- from 10 to 25%. LB broth with NaCl (3.5-30% w/v) and KClO4- (250-10000 mg/L) were used in independent trials to evaluate susceptibility to salinity and perchlorate, respectively. Isolates increased their biomass at 7.5 % (w/v) NaCl with optimal development at 3.5 % NaCl. Subsequently, ClO4- reduction was assessed using LB medium with 3.5% NaCl and 10000 mg/L ClO4-. BBCOL-009, BBCOL-014 and BBCOL-015 achieved 10%, 17%, and 25% reduction of ClO4-, respectively. The 16 S rRNA gene sequence grouped them as Bacillus flexus T6186-2, Bacillus marisflavi TF-11 (T), and Bacillus vietnamensis 15 - 1 (T) respectively, with < 97.5% homology. In addition, antimicrobial resistance to ertapenem, vancomycine, amoxicillin clavulanate, penicillin, and erythromycin was present in all the isolates, indicating their high adaptability to stressful environments. The isolated strains from marine sediments in Cartagena Bay, Colombia are suitable candidates to reduce perchlorate contamination in different environments. Although the primary focus of the study of perchlorate-reducing and resistant bacteria is in the ecological and agricultural realms, from an astrobiological perspective, perchlorate-resistant bacteria serve as models for astrobiological investigations.

Chemical constituents of the marine-derived fungus Acremonium sp. AN-13.

Two new compounds named 3(S)-hydroxy-1-(2,4,5-trihydroxy-3,6- dimethylphenyl)-hex-4E-en-1-one (1) and acremonilactone (2), together with nine known compounds (3-11), were isolated from the fermentation broth of Acremonium sp. associated with marine sediments collected from South China Sea. NMR and HRESIMS spectroscopic analysis elucidated the structure of two new compounds. Compound 2 had characteristic rotary gate shape skeleton with a six-membered lactone. Compounds 1 and 9 showed DPPH radical scavenging activity with inhibition rates of 96.50 and 85.95% at the concentration of 0.5 mg/ml, respectively. Moreover, compounds 4, 6 and 11 showed definite antibacterial activity against Staphylococcus aureus ATCC 6538.

Marine diatoms record Late Holocene regime shifts in the Pikialasorsuaq ecosystem.

The Pikialasorsuaq (North Water polynya) is an area of local and global cultural and ecological significance. However, over the last decades, the region has been subject to rapid warming, and in some recent years, the seasonal ice arch that has historically defined the polynya's northern boundary has failed to form. Both factors are deemed to alter the polynya's ecosystem functioning. To understand how climate-induced changes to the Pikialasorsuaq impact the basis of the marine food web, we explored diatom community-level responses to changing conditions, from a sediment core spanning the last 3800 years. Four metrics were used: total diatom concentrations, taxonomic composition, mean size, and diversity. Generalized additive model statistics highlight significant changes at ca. 2400, 2050, 1550, 1200, and 130 cal years BP, all coeval with known transitions between colder and warmer intervals of the Late Holocene, and regime shifts in the Pikialasorsuaq. Notably, a weaker/contracted polynya during the Roman Warm Period and Medieval Climate Anomaly caused the diatom community to reorganize via shifts in species composition, with the presence of larger taxa but lower diversity, and significantly reduced export production. This study underlines the high sensitivity of primary producers to changes in the polynya dynamics and illustrates that the strong pulse of early spring cryopelagic diatoms that makes the Pikialasorsuaq exceptionally productive may be jeopardized by rapid warming and associated Nares Strait ice arch destabilization. Future alterations to the phenology of primary producers may disproportionately impact higher trophic levels and keystone species in this region, with implications for Indigenous Peoples and global diversity.

Vallitalea longa sp. nov., an anaerobic bacterium isolated from marine sediment.

A novel bacterium, strain SH18-1T, was isolated from marine sediment collected near Sado Island in the Sea of Japan. This strain was strictly anaerobic, Gram-stain-negative, non-spore-forming, rod-shaped, motile, and mesophilic. It grew at 15-40 °C (optimum, 30-35 °C), at a NaCl concentration of 0.2-5.0 % (w/v; optimum, 1.5-2.5 %), and at pH 5.5-8.5 (optimum, pH 7.0). Results of 16S rRNA gene phylogenetic analysis showed a similarity value of 97.49 % between strain SH18-1T and Vallitalea guaymasensis Ra1766G1T, which was the most closely related species. The genome size of strain SH18-1T was 5.71 Mb and its G+C content was 30.2 mol%. Genome sequence analyses for comparison between strain SH18-1T and V. guaymasensis Ra1766G1T showed values lower than the threshold for species demarcation determined using the Genome-to-Genome Distance Calculator and the Average Nucleotide Identity Calculator. Elemental sulphur, sulphate, thiosulphate, sulphite, fumarate, nitrate, and nitrite were not used as terminal electron acceptors. The major fatty acids in strain SH18-1T were iso-C15 : 0, anteiso-C15 : 0, and C16 : 0, and the detected polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, glycolipid, three unidentified phospholipids, and one unidentified polar lipid. From these results, strain SH18-1T (=NBRC 115488T=DSM 114058T) is suggested to represent a novel species of the genus Vallitalea and the name Vallitalea longa sp. nov. is proposed.

Muricauda meishanensis sp. nov., a facultative anaerobic bacterium belonging to the family Flavobacteriaceae isolated from marine sediment in the East China Sea.

A facultative anaerobic, Gram-strain-negative, rod-shaped bacterium (strain NBU2970T) was isolated by using modified ichip in situ cultivation from a marine sediment sample collected from Meishan Island in the East China Sea. Strain NBU2970T grew optimally at 37 °C, with a NaCl concentration of 2.0 % (w/v) and at pH 7.0. The 16S rRNA gene sequence analyses revealed that strain NBU2970T represents a novel species with the genus Muricauda, sharing highest sequence identities with Muricauda beolgyonensis BB-My12T (96.1 %), Muricauda alvinocaridis SCR12T (96.0 %), Muricauda taeanensis 105T (96.0 %) and Muricauda ruestringensis B1T (95.6 %). Phylogenetic analyses also indicated that strain NBU2970T clustered with the genus Muricauda and was closely related to M. beolgyonensis BB-My12T and M. ruestringensis B1T. The draft genome sequence of strain NBU2970T was composed of six contigs with a size of 3.2 Mbp, containing 3045 protein-coding genes and 38 RNA genes. The DNA G+C content was 43.8 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU2970T and related species of the genus Muricauda were well below the threshold limit for prokaryotic species delineation. The major cellular fatty acids were iso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The only respiratory quinone was MK-6. The major polar lipid was phosphatidylethanolamine. Based on its phenotypic, chemotaxonomic and genotypic data, strain NBU2970T is considered to be a representative of a novel species in the genus Muricauda, for which the name Muricauda meishanensis sp. nov. is proposed. The type strain is NBU2970T (=KCTC 82915T=MCCC 1K06394T).

Mariluticola halotolerans gen. nov., sp. nov., a novel member of the family Devosiaceae isolated from South China Sea sediment.

A novel member of class Alphaproteobacteria was isolated from marine sediment of the South China Sea. Cells of strain LMO-2T were Gram-stain negative, greyish in colour, motile, with a single lateral flagellum and short rod in shape with a slight curve. Strain LMO-2T was positive for oxidase and negative for catalase. The bacterium grew aerobically at 10-40 °C (optimum, 25-30 °C), pH 5.5-10.0 (optimum, pH 7.0) and 0-9 % NaCl (w/v; optimum, 2-3 %). Phylogenetic analysis of the 16S rRNA gene sequence and phylogenomic analysis of the whole genome sequence indicated that strain LMO-2T represents a new genus and a new species within the family Devosiaceae, class Alphaproteobacteria, phylum Pseudomonadota. Comparisons of the 16S rRNA gene sequences of strain LMO-2T showed 94.8 % similarity to its closest relative. The genome size is ~3.45 Mbp with a DNA G+C content of 58.17 mol%. The strain possesses potential capability for the degradation of complex organic matter, i.e. fatty acid and benzoate. The predominant cellular fatty acids (>10 %) were C16 : 0 and C18 : 1 ω7c 11-methyl. The sole respiratory quinone was ubiquinone-10. The major identified polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phospholipid. Based on the polyphasic taxonomic data, strain LMO-2T represents a novel genus and a novel species for which the name Mariluticola halotolerans gen. nov., sp. nov., was proposed in the family Devosiaceae. The type strain is LMO-2T (=CGMCC 1.19273T=JCM 34934T).

Gillisia lutea sp. nov., isolated from marine aluminium residues from the Mediterranean sea.

A novel Gram-reaction-negative, facultatively anaerobic, rod-shaped, non-motile, non-spore forming, orange-pigmented bacterium identified as M10.2AT, was isolated from marine residues submerged on the Malva-rosa beach (València, Spain), on the western coast of the Mediterranean Sea. This strain was catalase-positive and oxidase-negative and grew under mesophilic, neutrophilic and halophilic conditions. With respect to the 16S rRNA gene sequences, M10.2AT showed similarities with Gillisia mitskevichiae DSM 19839T and Gillisia hiemivida IC154T (97.57 and 97.50 % gene sequence similarity, respectively). The genome of M10.2AT was sequenced and has been deposited in the DDBJ/ENA/GenBank databases under the accession code JAKGTH000000000. The genomic DNA G+C content was 36.13 %. Its adscription to a novel species of the genus Gillisia was confirmed by the genomic indexes average nucleotide identity by blast (ANIb) and digital DNA-DNA hybridisation (dDDH). The major fatty acids were iso-C15 : 0, iso-C15 : 1G, iso-C16 : 0 3-OH, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c/C16 : 1ω6c). According to the results of this polyphasic study, strain M10.2AT represents a novel species of the genus Gillisia, for which name Gillisia lutea sp. nov. (type strain M10.2AT = CECT 30308T = DSM 112385T) is proposed.

Maritalea mediterranea sp. nov., isolated from marine plastic residues.

A novel Gram-reaction-negative, aerobic, motile, rod-shaped, grey bacterium, strain P4.10XT, was isolated from plastic debris sampled from shallow waters in the Mediterranean Sea (Valencia, Spain). P4.10XT was catalase- and oxidase-positive, and grew under mesophilic, neutrophilic and halophilic conditions. The 16S rRNA gene sequences revealed that P4.10XT was closely related to Maritalea myrionectae DSM 19524T and Maritalea mobilis E6T (98.25 and 98.03 % sequence similarity, respectively). The DNA G+C content of the genome sequence of P4.10XT was 53.66 %. The genomic indexes average nucleotide identity by blast (ANIb) and digital DNA-DNA hybridization (dDDH) confirmed its classification as representing a novel species of the genus Maritalea. The predominant fatty acids were summed feature 8 (C18 : 1ω7c/C18 : 1ω6c) and C18 : 1 ω7c 11-methyl. The results of this polyphasic study confirm that P4.10XT represents a novel species of the genus Maritalea, for which the name Maritalea mediterranea sp. nov. is proposed (type strain P4.10XT=CECT 30306T = DSM 112386T).

Actinoplanes maris sp. nov., isolated from marine sediment.

A novel actinobacterium strain (M4I6T) was isolated from marine sediment collected in Megas Gialos, Syros, Greece. On the basis of 16S rRNA gene sequence analysis, strain M4I6T was indicated as belonging to the genus Actinoplanes, with high similarity to 'Actinoplanes solisilvae' LAM7112T (97.9 %), Actinoplanes ferrugineus IFO 15555T (97.6 %), Actinoplanes cibodasensis LIPI11-2-Ac042T (97.2 %) and Actinoplanes bogorensis LIPI11-2-Ac043T (97.2 %). Phylogenetic analysis of the 16S rRNA gene sequence of strain M4I6T showed that the strain formed a stable subclade with 'A. solisilvae' LAM7112T. The cell wall of the novel isolate contained meso-diaminopimelic acid and the whole-cell sugars were xylose, glucose and ribose. The predominant menaquinones were MK-9(H4), MK-9(H2) and MK-9(H8). The phospholipid profile comprised phosphatidylethanolamine, phosphatidylinositol, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannosides and an unknown phospholipid. The major fatty acids (>5 %) were anteiso-C16 : 0, iso-C17 : 0, 10-methyl-C16 : 0, C15 : 0, iso-C16 : 0 and C17 : 0. Genome sequencing showed a DNA G+C content of 70.9 mol%. However, the low average nucleotide identity value, digital DNA-DNA hybridization and average amino acid identity values demonstrated that strain M4I6T could be readily distinguished from its closest related species. Based on data from this polyphasic study, strain M4I6T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes maris sp. nov. is proposed. The type strain is M4I6T (=DSM 101017T=CGMCC 4.7854T).

Metagenomic Views of Microbial Communities in Sand Sediments Associated with Coral Reefs.

Reef sediments, the home for microbes with high abundances, provide an important source of carbonates and nutrients for the growth and maintenance of coral reefs. However, there is a lack of systematic research on the composition of microbial community in sediments of different geographic sites and their potential effect on nutrient recycling and health of the coral reef ecosystem. In combination of biogeochemical measurements with gene- and genome-centric metagenomics, we assessed microbial community compositions and functional diversity, as well as profiles of antibiotic resistance genes in surface sediments of 16 coral reef sites at different depths from the Xisha islands in the South China Sea. Reef sediment microbiomes are diverse and novel at lower taxonomic ranks, dominated by Proteobacteria and Planctomycetota. Most reef sediment bacteria potentially participate in biogeochemical cycling via oxidizing various organic and inorganic compounds as energy sources. High abundances of Proteobacteria (mostly Rhizobiales and Woeseiales) are metabolically flexible and contain rhodopsin genes. Various classes of antibiotic resistance genes, hosted by diverse bacterial lineages, were identified to confer resistance to multidrug, aminoglycoside, and other antibiotics. Overall, our findings expanded the understanding of reef sediment microbial ecology and provided insights for their link to the coral reef ecosystem health.

Depth-Dependent Distribution of Prokaryotes in Sediments of the Manganese Crust on Nazimov Guyots of the Magellan Seamounts.

Deep ocean polymetallic nodules, rich in cobalt, nickel, and titanium which are commonly used in high-technology and biotechnology applications, are being eyed for green energy transition through deep-sea mining operations. Prokaryotic communities underneath polymetallic nodules could participate in deep-sea biogeochemical cycling, however, are not fully described. To address this gap, we collected sediment cores from Nazimov guyots, where polymetallic nodules exist, to explore the diversity and vertical distribution of prokaryotic communities. Our 16S rRNA amplicon sequencing data, quantitative PCR results, and phylogenetic beta diversity indices showed that prokaryotic diversity in the surficial layers (0-8 cm) was > 4-fold higher compared to deeper horizons (8-26 cm), while heterotrophs dominated in all sediment horizons. Proteobacteria was the most abundant taxon (32-82%) across all sediment depths, followed by Thaumarchaeota (4-37%), Firmicutes (2-18%), and Planctomycetes (1-6%). Depth was the key factor controlling prokaryotic distribution, while heavy metals (e.g., iron, copper, nickel, cobalt, zinc) can also influence significantly the downcore distribution of prokaryotic communities. Analyses of phylogenetic diversity showed that deterministic processes governing prokaryotic assembly in surficial layers, contrasting with stochastic influences in deep layers. This was further supported from the detection of a more complex prokaryotic co-occurrence network in the surficial layer which suggested more diverse prokaryotic communities existed in the surface vs. deeper sediments. This study expands current knowledge on the vertical distribution of benthic prokaryotic diversity in deep sea settings underneath polymetallic nodules, and the results reported might set a baseline for future mining decisions.

Oricola nitratireducens sp. nov., a novel nitrate reducing bacterium isolated from marine sediment in East China Sea.

A novel strain designated NBU1457T, was isolated from marine sediment sampled on Meishan Island located in the East China Sea. Cells of strain NBU1457T was Gram-negative, facultatively anaerobic, non-motile and ovoid-shaped. Strain NBU1457T grew optimally at 37 °C, NaCl concentration of 2.0-3.0% (w/v) and pH 6.5-7.5. Catalase and oxidase activities, urease, nitrate reduction and H2S production were positive. Indole production, methyl red reaction, hydrolysis of starch, gelatin, casein, Tweens 20, 40, 60 and 80 were negative. Comparative analysis of the 16S rRNA gene sequence showed highest similarities to the species with validated name Oricola thermophila MEBiC13590T (98.8%), Oricola cellulosilytica CC-AMH-0 T (97.9%) and Oricola indica JL-62 T (97.9%). Phylogenetic analyses indicated that strain NBU1457T clustered with the genus Oricola and closely related to strains Oricola thermophila MEBiC13590T, Oricola cellulosilytica CC-AMH-0 T and Oricola indica JL-62 T. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU1457T and related species of genus Oricola were well below the threshold limit for prokaryotic species delineation. The DNA G + C content was 63.2%. The major cellular fatty acid was summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylmonomethylethanolamine, sulfoquinovosyldiacylglycerol and phosphatidylglycerol. The only respiratory quinone was ubiquinone-10 (Q-10). Combining results of our phenotypic, chemotaxonomic and genotypic data, strain NBU1457T is considered to be a representative in the genus Oricola, which the name Oricola nitratireducens sp. nov. is proposed. The type strain of the new species is NBU1457T (= KCTC 82225 T = MCCC 1K04764T).