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Anthracnose disease, caused by the Colletotrichum gloeosporioides species, affects vegetables, fruits, pulses, and cereals, leading to significant economic losses worldwide. Although many synthetic fungicides are used to control this pathogen, eco-friendly biological alternatives are gaining popularity. This study focuses on isolating and purifying chitinase (Af Chi)from a marine bacterium and testing its antifungal efficacy against C. gloeosporioides spore germination by targeting the chitin in the fungal cell wall. The chitinase was purified from a marine bacterium A. faecalis from the Arabian Sea and had a molecular mass of 45 kDa and a specific activity of 84.6 U/mg. Af Chi worked best at 50 °C and pH 7.0 in Tris HCl buffer. Na+ ion was the highest cofactor, highlighting the halophilic nature of this chitinase. K+, Ca2+, Cu2+, Mg2+, Mn2+, and EDTA also increased activity, while Fe3+, Zn2+, Co2+, and Pb2+ decreased it. The Km and Vmax values were 1.87 µg/mL and 17.45 U/mL, respectively. Purified Af Chi at 10 mg/mL completely inhibited spore germination within 8 h and reduced the size of the spores. Key points: The chitinase remain stable at high temperature. The chitinase from A. faecalis shown positive result in development of natural bio-fungicide. [ABSTRACT FROM AUTHOR]

Endo-β-1,3-glucanase is a glycoside hydrolase (GH) that plays an essential role in the mineralization of β-glucan polysaccharides. In this study, the novel gene encoding an extracellular, non-modular GH16 endo-β-1,3-glucanase (GluH) from Hymenobacter siberiensis PAMC 29290 isolated from Arctic marine sediment was discovered through an in silico analysis of its whole genome sequence and subsequently overexpressed in Escherichia coli BL21. The 870-bp GluH gene encoded a protein featuring a single catalytic GH16 domain that shared over 61% sequence identity with uncharacterized endo-β-1,3-glucanases from diverse Hymenobacter species, as recorded in the National Center for Biotechnology Information database. The purified recombinant endo-β-1,3-glucanase (rGluH: 31.0 kDa) demonstrated peak activity on laminarin at pH 5.5 and 40°C, maintaining over 40% of its maximum endo-β-1,3-glucanase activity even at 25°C. rGluH preferentially hydrolyzed D-laminarioligosaccharides and β-1,3-linked polysaccharides, but did not degrade D-laminaribiose or structurally unrelated substrates, confirming its specificity as a true endo-β-1,3-glucanase without ancillary GH activities. The biodegradability of various substrate polymers by the enzyme was evaluated in the following sequence: laminarin > barley β-glucan > carboxymethyl-curdlan > curdlan > pachyman. Notably, the specific activity (253.1 U mg–1) and catalytic efficiency (kcat/Km: 105.72 mg–1 s–1 mL) of rGluH for laminarin closely matched its specific activity (250.2 U mg–1) and kcat/Km value (104.88 mg–1 s–1 mL) toward barley β-glucan. However, the kcat/Km value (9.86 mg–1 s–1 mL) of rGluH for insoluble curdlan was only about 9.3% of the value for laminarin, which correlates well with the observation that rGluH displayed weak binding affinity (< 40%) to the insoluble polymer. The biocatalytic hydrolysis of D-laminarioligosaccharides with a degree of polymerization between 3 and 6 and laminarin generally resulted in the formation of D-laminaribiose as the predominant product and D-glucose as the secondary product, with a ratio of approximately 4:1. These findings suggest that highly active rGluH is an acidic, cold-adapted D-laminaribiose- and D-glucose-releasing GH16 endo-β-1,3-glucanase, which can be exploited as a valuable biocatalyst for facilitating low temperature preservation of foods. [ABSTRACT FROM AUTHOR]

Most organic carbon delivered to the seafloor is degraded within the bioturbated layer. Theory and empirical evidence have shown that organic carbon reactivity relates to the age of a particle. However, due to particle mixing, the age‐depth linear relation induced by sediment accretion is obfuscated. Here we combine a Lagrangian particle tracking model that resolves the age distribution of particles in the bioturbated zone and couple it to age‐dependent organic carbon degradation. Depth profiles for organic carbon concentration, reactivity and degradation rate are presented for sediments receiving low and high reactivity organic carbon in coastal, continental slope and deep‐sea environments. Our results show that a simple first‐order kinetics model suffices for well‐mixed sediments and systems receiving pre‐processed materials. A reactive continuum approach is needed for poorly mixed sediments receiving highly reactive organic carbon and for sediments below the bioturbated layer. Plain Language Summary: Animals inhabiting marine sediments mix particles and impact organic carbon degradation kinetics and degradation rates. Experiments and theory have shown that organic carbon reactivity declines as degradation progresses with time. However, most studies employ a constant reactivity. Here we couple an individual particle mixing model with age‐dependent reactivity and show that a constant reactivity model is adequate for well‐mixed sediments and for sediments receiving organic carbon that has already been degraded elsewhere. An age‐dependent reactivity model is needed for poorly mixed sediments receiving highly reactive organic carbon. Key Points: Age‐dependent organic carbon kinetics is coupled to a Lagrangian particle tracking modelOrganic carbon concentrations, reactivities and degradation rates in the bioturbated zone are presentedA simple first‐order (one‐G) model suffices for well‐mixed sediments and sediments receiving pre‐processed organic carbon [ABSTRACT FROM AUTHOR]

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 β- 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). [ABSTRACT FROM AUTHOR]

Recent concerns that commercial bottom trawling can contribute to a significant release of sequestered marine carbon have highlighted a need for research in this area. Here, a Before-After Control-Impact (BACI) experimental design was utilized in a previously untrawled area of the eastern Bering Sea. Six pairs of experimental and control corridors were sampled before, after, and 1 year after a trawl disturbance. Each experimental corridor was fished four consecutive times over ∼12 h with a commercial otter trawl. Results were contextualized with minimum detectable effects (MDE), and showed no evidence of a trawl effect on total organic carbon (P  = .999, MDE ± 0.05% TOC), total nitrogen (P  = .999, MDE ± 0.02% TN), δ13C, and δ15N isotope ratios and sediment size classes. Interannual changes observed in δ15N, sand, silt, and clay are attributed to natural variation. The study suggests that the characteristics of the study site, such as storm disturbances, high sand content, and low carbon content, limited the bottom-trawl effect on sediment composition following this initial trawl disturbance. The findings highlight the importance of site-specific studies that account for local conditions to support best management practices for commercial bottom trawling. [ABSTRACT FROM AUTHOR]

Archaeal isoprenoid glycerol dibiphytanyl glycerol tetraethers (GDGTs) preserved in sediments are popular tools for the reconstruction of past temperature in the global ocean. Whereas the most common GDGTs have been well studied through environmental and culture studies, their hydroxylated version (OH-GDGTs) is just emerging as a new proxy. Some empirical evidence suggests that the distribution of OH-GDGTs may capture sea surface temperature variability. However, the effects of additional environmental factors on OH-GDGT distributions have not been rigorously tested, and evidence suggests that salinity, sea ice, seasonality, terrestrial input, and water depth may be additional factors in some settings. In this study, we analyzed the distribution of OH-GDGTs in modern and Holocene marine sediment from the North Iceland Shelf. By statistically comparing the biomarker datasets against a collection of modern instrumental and paleoceanographic records, we separated which environmental variables may be controlling OH-GDGT-derived proxies around Iceland. In contrast to prevailing theory, we found that nitrate concentrations and water-column stratification are best correlated to OH-GDGT distributions, and not temperature. These results hold important implications for the application of OH-GDGT proxies in high-latitude oceans, particularly in highly stratified locations, as well as for future studies on the biological sources and functionality of these lipids. Given the current complexity of proxy interpretation, we urge caution in the current application of OH-GDGTs as a tool in paleotemperature reconstructions. [ABSTRACT FROM AUTHOR]

Uplifted occurrences of fine-grained glaciogene marine sediments are found throughout the northern hemisphere. These sediments could be used to produce local construction materials, to rely less on imported construction materials from southern regions. In this study, a representative occurrence from Ilulissat, West Greenland, was investigated as a potential resource for local brick production. The study comprised three parts: (1) raw material characterization based on grain size distribution, major element chemistry, including total carbon, sulfur, and chloride concentrations, mineralogy, morphology, and Atterberg limits; (2) the production of test bricks at a Danish brickwork; and (3) testing of the bricks based on total shrinkage, water absorption, hygroscopic adsorption, open porosity, bulk density, compression strength, and mineralogy. The bricks produced proved to have excellent compression strength, low open porosity, and low water absorption. The shrinkage could be reduced by adding 10% chamotte to the marine sediment. Based on the investigated properties, this indicates that this type of clay is highly suitable as a resource for bricks. [ABSTRACT FROM AUTHOR]

Abstract Anthracnose disease, caused by the Colletotrichum gloeosporioides species, affects vegetables, fruits, pulses, and cereals, leading to significant economic losses worldwide. Although many synthetic fungicides are used to control this pathogen, eco-friendly biological alternatives are gaining popularity. This study focuses on isolating and purifying chitinase ( Af Chi)from a marine bacterium and testing its antifungal efficacy against C. gloeosporioides spore germination by targeting the chitin in the fungal cell wall. The chitinase was purified from a marine bacterium A. faecalis from the Arabian Sea and had a molecular mass of 45 kDa and a specific activity of 84.6 U/mg. Af Chi worked best at 50 °C and pH 7.0 in Tris HCl buffer. Na+ ion was the highest cofactor, highlighting the halophilic nature of this chitinase. K+, Ca2+, Cu2+, Mg2+, Mn2+, and EDTA also increased activity, while Fe3+, Zn2+, Co2+, and Pb2+ decreased it. The Km and Vmax values were 1.87 µg/mL and 17.45 U/mL, respectively. Purified Af Chi at 10 mg/mL completely inhibited spore germination within 8 h and reduced the size of the spores.

Abstract Anisotropic structures within the crust are frequently perceived to originate from stress-induced cracks, which have been mainly estimated on land through different wave speeds of orthogonally polarized S waves propagating in the anisotropic media. However, such estimations of crustal anisotropic structures in ocean areas, particularly for subduction zones around trenches, have not been investigated in detail due to the lack of long-term ocean bottom observations. In this study, we used ocean bottom seismometers of a permanent network deployed across the Japan Trench and the southern part of the Kuril Trench and applied the shear-wave splitting analysis to P-to-s converted waves extracted by receiver function analyses using teleseismic events. We estimated the anisotropic structures in marine sediments and oceanic crust for the incoming Pacific Plate and marine sediments for the overriding North American Plate. The obtained fast polarization directions for the incoming plate are mainly oriented to be parallel to the trench axis for the marine sediment and oceanic crust, which are formed by normal faults and cracks due to the upward plate bending in the outer-rise region, whereas results for marine sediments at the northern part of the Japan Trench are obliquely aligned to the trench axis. The oblique direction is consistent with the magnetic lineations of the incoming plate, indicating that ancient faults within the plate, which were formed in the shallow part of the crust during the creation of the oceanic plate at the ridge, are reactivated by the plate flexure. For the overriding plate, the fast polarization directions in the northern and southern parts of the study area are nearly normal to the trench axis. The central part shows two distinct features: the fast polarization directions parallel to the trench axis and small degrees of anisotropy. These patterns may reflect crack alignments associated with the lateral variation in postseismic crustal deformation after the 2011 Tohoku-Oki earthquake. Our results suggest substantial lateral variations in the stress field at the tip of the overriding plate along the strike direction. Graphical Abstract

Anisotropic structures within the crust are frequently perceived to originate from stress-induced cracks, which have been mainly estimated on land through different wave speeds of orthogonally polarized S waves propagating in the anisotropic media. However, such estimations of crustal anisotropic structures in ocean areas, particularly for subduction zones around trenches, have not been investigated in detail due to the lack of long-term ocean bottom observations. In this study, we used ocean bottom seismometers of a permanent network deployed across the Japan Trench and the southern part of the Kuril Trench and applied the shear-wave splitting analysis to P-to-s converted waves extracted by receiver function analyses using teleseismic events. We estimated the anisotropic structures in marine sediments and oceanic crust for the incoming Pacific Plate and marine sediments for the overriding North American Plate. The obtained fast polarization directions for the incoming plate are mainly oriented to be parallel to the trench axis for the marine sediment and oceanic crust, which are formed by normal faults and cracks due to the upward plate bending in the outer-rise region, whereas results for marine sediments at the northern part of the Japan Trench are obliquely aligned to the trench axis. The oblique direction is consistent with the magnetic lineations of the incoming plate, indicating that ancient faults within the plate, which were formed in the shallow part of the crust during the creation of the oceanic plate at the ridge, are reactivated by the plate flexure. For the overriding plate, the fast polarization directions in the northern and southern parts of the study area are nearly normal to the trench axis. The central part shows two distinct features: the fast polarization directions parallel to the trench axis and small degrees of anisotropy. These patterns may reflect crack alignments associated with the lateral variation in postseismic crustal deformation after the 2011 Tohoku-Oki earthquake. Our results suggest substantial lateral variations in the stress field at the tip of the overriding plate along the strike direction. [ABSTRACT FROM AUTHOR]

The Mazarrón 2 shipwreck was found in 1994 on the beach of Playa de la Isla (Mazarrón, Murcia, Spain). This finding is extremely important because the boat and its lead cargo were still in a reasonable conservation state and, therefore, provided new data on naval construction, commercial goods, navigation routes, and the relationships between the Phoenicians and the local population in the 7th–6th century BC. Currently, the shipwreck remains underwater, protected by a metallic coffer. In the last 2 years, a Preliminary Studies Project has been carried out, supported by national and regional public institutions. This research aims to know the shipwreck's conservation state and to determine the extraction and conservation methods at the Museo Nacional de Arqueología Subacuática ARQVA (Cartagena, Spain), where the conservation and restoration treatment will be conducted. The sampling strategy and analytical study included not only wood and other materials from the shipwreck and its cargo but also the seawater and the seabed materials in the vicinity of the shipwreck. This paper presents the results of the geochemical study of the archeological site. The applied methodology included physico-chemical tests, X-ray diffraction, optical microscopy, FTIR spectroscopy, field-emission scanning electron microscopy coupled with X-ray microanalysis, and X-ray microscopy. The results indicated that, despite the wreck being buried at a shallow depth (less than 50 cm) in a marine environment with a water column of 2–2.5 m, influenced by complex coastal dynamics that favor an oxic environment, early diagenetic processes like the formation of pyrite framboids are particularly intense in the pores and internal channels of the wreck's wood, where a different dysoxic–anoxic environment prevails. These processes have been the main mechanisms to have affected the wreck and are related to the biogeochemistry of sediments. The sediments have been confirmed to be closely related to the geological context of the Mazarrón region. The conducted study found no significant evidence of pollution due to the lead cargo. [ABSTRACT FROM AUTHOR]

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 KClO4ˉ (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, ClO4ˉ reduction was assessed using LB medium with 3.5% NaCl and 10000 mg/L ClO4ˉ. BBCOL-009, BBCOL-014 and BBCOL-015 achieved 10%, 17%, and 25% reduction of ClO4ˉ, 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. [ABSTRACT FROM AUTHOR]

Most contaminants in the sea originate from land sources. Radionuclides in sea water are transported by sea currents. Marine sediment is a physical trap for pollutants that are introduced to the environment and play an important role in radiological studies. Radionuclides from seawater bound to particulates sink to the seabed. Their resuspension causes the reintroduction of pollutants to the water column. Remobilization and horizontal/vertical transport by various processes may occur. Long-lived radionuclides become buried in sub-surface sediment. Grain size sediment classification and sediment geochemical composition all play a significant role in the development of the radionuclide content of marine sediment. Atmospheric fallout from the Chernobyl and the Fukushima accidents, atmospheric nuclear weapon testing, releases from nuclear industry plants, river runoff, and to a lesser extent directed and submarine groundwater discharges are the major sources of radionuclides in the marine environment. [ABSTRACT FROM AUTHOR]

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AbstractSubmarine landslides are a critical geological process that significantly influences seafloor stability and geological evolution, making them a focal point of geological disaster research. Particularly, rapid sedimentation as a crucial preconditioning factor for submarine landslide initiation is increasingly recognized in contemporary research. However, no comprehensive review currently examines the correlation between rapid sedimentation and submarine landslides. To elucidate the interaction mechanisms between submarine landslides and rapid sedimentation and to provide a new theoretical foundation for the prediction and prevention of geological hazards, the study categorizes three primary sedimentation patterns in marine environments and establishes a detailed historical database of sedimentation-related submarine landslide events. Moreover, the paper systematically reviews and critiques the existing research methods and advancements in addressing rapid sedimentation-related submarine landslides, and a bibliometric analysis of recent research progress is conducted. Finally, the study highlights several challenges in the study of rapid sedimentation and proposes future recommendations, aiming to provide robust support for the in-depth investigation of submarine landslides. [ABSTRACT FROM AUTHOR]

Knowledge of the ecological mechanisms governing N2O cycling in marine sediments lags that of water columns and terrestrial soils, leaving much to be learned about how microbial community dynamics relate to variability in sediment N2O fluxes. The present study assesses these relationships across two distinct environments by focusing on the community structure and activity of N2O reducing microorganisms. The N2O sink capacity of minimally impacted Bermudian mangrove sediments was first estimated using trace‐level microsensors and profile interpretation modeling. Molecular data obtained from these sediments were then compared with those from the Northeast Subarctic Pacific (NESAP) outer continental margin, where previous measurements suggest considerable N2O effluxes. Net N2O uptake was observed for mangrove sediments under ambient and elevated dissolved inorganic nitrogen concentrations (−0.22 ± 0.15 to −0.30 ± 0.26 μmol N2O m−2 d−1), suggesting the microbial potential for N2O consumption exceeded the potential for production via combined nitrification and denitrification. Targeting of bacterial nosZI and nosII gene clusters for quantification using qPCR indicated higher abundance and expression of non‐denitrifier nosZII genes in mangrove sediments demonstrating net N2O uptake. Net N2O production in NESAP sediments was associated with higher abundance and expression of nosZI genes associated with canonical denitrifiers. These results suggest that organisms possessing atypical nosZII genes may act as important N2O scavengers in low‐nitrogen coastal sediments. Plain Language Summary: Nitrous oxide (N2O) is potent greenhouse gas that contributes to ozone depletion in the stratosphere, and atmospheric concentrations a rising as a result of human activities. The production and consumption of N2O in the environment is mediated by microorganisms, and the balance between the two processes is governed by environmental factors such as concentrations of dissolved oxygen and fixed nitrogen. However, little is known about the relationships between microbial community dynamics and rates of N2O production and consumption, especially in sediment environments. We found that minimally impacted mangrove sediments of Bermuda are net consumers of N2O, and continue to consume N2O following short term nitrogen enrichments. This N2O sink capacity was linked to higher abundances and activity levels of atypical N2O reductase genes when compared to sediments that produce N2O. These genes facilitate the consumption of N2O, and frequently occur in microbes that do not have the capacity to produce N2O via denitrification. This study provides further insight into the role of microbial community structure in regulating sediment N2O cycling, and argues for targeted conservation and restoration of coastal systems where sediment environments are in close proximity to the atmosphere. Key Points: The N2O sink capacity of minimally impacted Bermudian mangrove sediments is resilient against modest, short‐term nutrient enrichmentHigh prevalence of non‐denitrifier nosZII genes in mangrove sediments implies a crucial role as N2O scavengers in low‐nitrogen systemsNet N2O production in NESAP sediments is associated with higher expression of nosZI genes associated with canonical denitrifiers [ABSTRACT FROM AUTHOR]

Daily industrial activities pose a significant risk of environmental contamination through the release of toxic chemicals, including heavy metals, radionuclides and organic pollutants. Coastal marine areas, estuaries and harbors serve as primary hotspots for such pollution, with marine sediments acting as the ultimate sink for industrial and urban discharges, posing a serious environmental problem. Addressing this pressing issue requires the adoption of environmentally friendly technologies for the remediation and recovery of contaminated marine sediments. This paper provides a comprehensive review of different approaches for the remediation of contaminated sediments, focusing on the principle of electrokinetic remediation, with special emphasis on the use of microorganisms. A bibliometric analysis of key articles in the field is presented to elucidate the most important findings, particularly in the marine environment. The current state-of-the-art is reported for soil and sediment remediation approaches, with the first large-scale experiments and a preliminary cost estimate reported. However, the limited information available on the applicability of these techniques in the marine environment is highlighted. The limitations and risks associated with an inadequate implementation of this technique are discussed while acknowledging the advantages it offers for in situ remediation in marine environments. [ABSTRACT FROM AUTHOR]

Sediment plays a pivotal role in deep-sea ecosystems by providing habitats for a diverse range of microorganisms and facilitates the cycling processes of carbon, sulfur and nitrogen. Beyond the normal seafloor (NS), distinctive geographical features such as cold seeps (CS) and hydrothermal vent (HV) are recognized as life oases harboring highly diverse microbial communities. A global atlas of microorganisms can reveal the notable association between geological processes and microbial colonization. However, a comprehensive understanding of the systematic comparison of microbial communities in sediments across various deep-sea regions worldwide and their contributions to Earth's elemental cycles remains limited. Analyzing metagenomic data from 163 deep-sea sediment samples across 73 locations worldwide revealed that microbial communities in CS sediments exhibited the highest richness and diversity, followed by HV sediments, with NS sediments showing the lowest diversity. The NS sediments were predominantly inhabited by Nitrosopumilaceae, a type of ammonia-oxidizing archaea (AOA). In contrast, CSs and HVs were dominated by ANME-1, a family of anaerobic methane-oxidizing archaea (ANME), and Desulfofervidaceae, a family of sulfate-reducing bacteria (SRB), respectively. Microbial networks were established for each ecosystem to analyze the relationships and interactions among different microorganisms. Additionally, we analyzed the metabolic patterns of microbial communities in different deep-sea sediments. Despite variations in carbon fixation pathways in ecosystems with different oxygen concentrations, carbon metabolism remains the predominant biogeochemical cycle in deep-sea sediments. Benthic ecosystems exhibit distinct microbial potentials for sulfate reduction, both assimilatory and dissimilatory sulfate reduction (ASR and DSR), in response to different environmental conditions. The presence of nitrogen-fixing microorganisms in CS sediments may influence the global nitrogen balance. In this study, the significant differences in the taxonomic composition and functional potential of microbial communities inhabiting various deep-sea environments were investigated. Our findings emphasize the importance of conducting comparative studies on ecosystems to reveal the complex interrelationships between marine sediments and global biogeochemical cycles.

Abstract Most organic carbon delivered to the seafloor is degraded within the bioturbated layer. Theory and empirical evidence have shown that organic carbon reactivity relates to the age of a particle. However, due to particle mixing, the age‐depth linear relation induced by sediment accretion is obfuscated. Here we combine a Lagrangian particle tracking model that resolves the age distribution of particles in the bioturbated zone and couple it to age‐dependent organic carbon degradation. Depth profiles for organic carbon concentration, reactivity and degradation rate are presented for sediments receiving low and high reactivity organic carbon in coastal, continental slope and deep‐sea environments. Our results show that a simple first‐order kinetics model suffices for well‐mixed sediments and systems receiving pre‐processed materials. A reactive continuum approach is needed for poorly mixed sediments receiving highly reactive organic carbon and for sediments below the bioturbated layer.

Abstract The analysis of eukaryotic environmental DNA (eDNA) in sediment has the potential for understanding past ecosystems, even for taxa lacking skeletons or preserved only as a part of necromass. Despite the paleoenvironmental and ecological importance of eukaryotic eDNA in marine sediment, the duration of remaining eDNA and the species of eDNA present in marine sediment has not been well investigated. Here, we analyzed eDNA extracted from 299 sediment samples down to 678 m below the seafloor at 40 geologically distinct sites. The results showed that eukaryotic eDNA was amplified from more than 80% of the sediments with a depositional age of less than 100,000 years. The eDNA was well conserved in anoxic sediments than in oxic sediments, with PCR success rates of 48% and 18%, respectively. The eukaryotic communities include non-benthic organisms such as marine plankton, including diatoms, dinoflagellates, and coccolithophores. A freshwater diatom genus Aulacoseira was detected in the Baltic Sea sediments from the last glacial lacustrine environment. These results provide new insights into the global-scale distribution of the past eukaryotic eDNA preserved in marine sediment.

A huge amount of phosphogypsum (PG) wastes generated from the processing phosphate ore in Tunisia Industrial Group Area—Gabes is getting discarded into the sea. Within this framework, the basic objective of this research is to elaborate and discuss a natural-based solution focused on phytoremediation of contaminated (PG) soils and marine sediments with the halophilic plant Salicornia europaea. A significant drop of the organic matter (53.09%), moisture (26.47%), and sediment porosity with (5.88%) was detected in the rhizosphere Salicornia europaea area (RS). Removal of hazardous elements concentrations, such as Pb, Fe, Cu, Cd, and Zn, between contaminated sediment (CS) and RS displayed a significant difference, ranging from 5.33 to 50.02% of hazardous elements removal concentration, which was observed in the rhizosphere zone. The microbiota of both areas (RS and CS) were analyzed by massive sequencing. In both samples, all the sequences belong to only four phyla: Firmicutes and, to a much lower extent, Proteobacteria, Bacteroidetes, and Actinobacteria. The CS sediment seems to be heavily polluted by human activities. Most of the found genera are inhabitants of the intestine of warm-blooded animals (Escherichia, Bacteroides, Prevotella, Faecalibacterium, Ruminococcus, Enterococcus); hence, activities in this area pose a health risk. On the other hand, it may be surprising that 76.4% of the total high-quality sequences retrieved from the RS sample were affiliated to the family Bacillaceae. The salinity of the studied soil exerts a stress on the microbial populations that inhabit it, directing the selection of halotolerant species. [ABSTRACT FROM AUTHOR]

Phthalic acid esters (PAEs) are widely used as plasticizers in industrial production. At present, this type of pollutant has been widely detected in the global environment. The distribution characteristics and ecological risk pollution of phthalate organic pollutants in seawater and sediments near Xiamen were evaluated, and gas chromatography-mass spectrometry was used to determine the concentration of PAEs in the samples. The results showed that a total of 11 PAEs compounds were mainly detected in the aqueous and sedimentary environmental media, and the total PAEs mass concentration in water ranged from 45.9-251.1 ng/L, with an average concentration of 109.2 ng/L. The concentration in sediment ranges from 8.12-50.29 μg/kg, with an average concentration of 27.7 μg/kg. The risk entropy method was used to assess the risk of PAEs in the near sea area, and the results showed that DBP has a moderate ecological risk level. It is necessary to further trace the pollution emissions of PAEs in these areas. [ABSTRACT FROM AUTHOR]

The analysis of eukaryotic environmental DNA (eDNA) in sediment has the potential for understanding past ecosystems, even for taxa lacking skeletons or preserved only as a part of necromass. Despite the paleoenvironmental and ecological importance of eukaryotic eDNA in marine sediment, the duration of remaining eDNA and the species of eDNA present in marine sediment has not been well investigated. Here, we analyzed eDNA extracted from 299 sediment samples down to 678 m below the seafloor at 40 geologically distinct sites. The results showed that eukaryotic eDNA was amplified from more than 80% of the sediments with a depositional age of less than 100,000 years. The eDNA was well conserved in anoxic sediments than in oxic sediments, with PCR success rates of 48% and 18%, respectively. The eukaryotic communities include non-benthic organisms such as marine plankton, including diatoms, dinoflagellates, and coccolithophores. A freshwater diatom genus Aulacoseira was detected in the Baltic Sea sediments from the last glacial lacustrine environment. These results provide new insights into the global-scale distribution of the past eukaryotic eDNA preserved in marine sediment. [ABSTRACT FROM AUTHOR]

Mercury (Hg) enrichment relative to total organic carbon (TOC) in sedimentary records has been widely used as a volcanism proxy. However, the depositional and diagenetic effects on Hg burial are not well understood, limiting the reliability of the proxy. Here, we report a systematic investigation of Hg sedimentation under well‐oxygenated bottom water. Most of the studied cores show total mercury content (THg) to TOC ratio between 50 and 300 ppb/%, including northwest Pacific ODP Site 1208, East Equatorial Pacific ODP Sites 677 and 1241, the Antarctic Zone ODP Site 1094, and East China Sea sediment core EC2005. The consistent THg/TOC ratio confirms the strong coupling between Hg and particulate organic matter (POM) despite large differences in geographic locations, sedimentation rates, TOC content, POM sources, and early diagenetic environments. Nevertheless, the THg/TOC ratio is higher in sediments under well‐oxygenated bottom water than in those under oxygen‐depleted waters, probably as a result of a higher degree of organic matter degradation in oxygenated sediments during early diagenesis. The THg in the high TOC variability section at Site 1208 is abnormally high, resulting in decoupling between Hg and POM. Mercury in this section is still leachable by oxidizing solution and has a similar trend of variability with easily reducible iron content, implying that the metal oxide‐organic matter association might act as Hg bounding phase. We suggest that the enriched Hg is probably supplied by the neighboring high TOC sediment. Therefore, while THg/TOC > 300 ppb/% could be considered as distinct Hg enrichment in sedimentary records, the diagenetic mobilization effect should be first excluded as the possible cause as demonstrated by the records of site 1208. Our study therefore provides new insights into the Hg cycle in the modern ocean and the utilization of Hg enrichment as a volcanism proxy. Key Points: Strong coupling between sedimentary Hg and particulate organic matter in an oxygenated marine environmentHg is relatively enriched compared to particulate organic matter during its aerobic degradationLarge change in the content of particulate organic matter causes its decoupling with Hg [ABSTRACT FROM AUTHOR]

Intertidal mudflats are susceptible to oil pollution due to their proximity to discharges from industries, accidental spills from marine shipping activities, oil drilling, pipeline seepages, and river outflows. The experimental study was divided into two periods. In the first period, microcosm trials were carried out to examine the effect of chemically modified biochar on biological hydrocarbon removal from sediments. The modified biochar's surface area increased from 2.544 to 25.378 m2/g, followed by a corresponding increase in the hydrogen-carbon and oxygen-carbon ratio, indicating improved stability and polarity. In the second period, the effect of exogenous fungus — Scedoporium sp. ZYY on the bacterial community structure was examined in relation to total petroleum hydrocarbon (TPH) removal. The maximum TPH removal efficiency of 82.4% was achieved in treatments with the modified biochar, followed by a corresponding increase in Fluorescein diacetate hydrolysis activity. Furthermore, high-throughput 16S RNA gene sequencing employed to identify changes in the bacterial community of the original sediment and treatments before and after fungal inoculation revealed Proteobacteria as the dominant phylum. In addition, it was observed that Scedoporium sp. ZYY promoted the proliferation of specific TPH-degraders, particularly, Hyphomonas adhaerens which accounted for 77% of the total degrading populations in treatments where TPH removal was highest. Findings in this study provide valuable insights into the effect of modified biochar and the fundamental role of exogenous fungus towards the effective degradation of oil-contaminated intertidal mudflat sediments. [ABSTRACT FROM AUTHOR]

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 β- 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). [ABSTRACT FROM AUTHOR]

Archaeal isoprenoid glycerol dibiphytanyl glycerol tetraethers (GDGTs) preserved in sediments are popular tools for the reconstruction of past temperature in the global ocean. Whereas the most common GDGTs have been well studied through environmental and culture studies, their hydroxylated version (OH-GDGTs) is just emerging as a new proxy. Some empirical evidence suggests that the distribution of OH-GDGTs may capture sea surface temperature variability. However, the effects of additional environmental factors on OH-GDGT distributions have not been rigorously tested, and evidence suggests that salinity, sea ice, seasonality, terrestrial input, and water depth may be additional factors in some settings. In this study, we analyzed the distribution of OH-GDGTs in modern and Holocene marine sediment from the North Iceland Shelf. By statistically comparing the biomarker datasets against a collection of modern instrumental and paleoceanographic records, we separated which environmental variables may be controlling OH-GDGT-derived proxies around Iceland. In contrast to prevailing theory, we found that nitrate concentrations and water-column stratification are best correlated to OH-GDGT distributions, and not temperature. These results hold important implications for the application of OH-GDGT proxies in high-latitude oceans, particularly in highly stratified locations, as well as for future studies on the biological sources and functionality of these lipids. Given the current complexity of proxy interpretation, we urge caution in the current application of OH-GDGTs as a tool in paleotemperature reconstructions.

Pockmarks are formed as a result of gas (methane) or/and groundwater outflow from the sea bottom. Methane, the second most important (after CO2) greenhouse gas, has a significant impact on biogeochemical processes in the bottom sediments by affecting the cycling of some elements, e.g. C, Fe, and S. Active pockmarks may also lead to changes in water column conditions by causing nutrients release from sediments. In the present study, we have focused on the impact of biogeochemical processes in pockmarks (methanogenesis, anaerobic methane oxidation, and groundwater seepage) on the transformation of iron (Fe) and the mineral composition of the sediment. In pore water, concentrations of hydrogen sulfide, phosphate, ammonia, sulfate, chloride, dissolved inorganic carbon, iron, and methane were analyzed. In the sediment, Fe speciation was performed using sequential extraction. The mineral composition was determined using powder X-Ray diffraction and scanning electron microscopy. The results from two pockmarks (with active gas seepage and groundwater infiltration) and two reference stations in the southern Baltic Sea show that geochemical conditions in pockmark sediments are significantly different from those in the typical muddy sea bottom. Pore water in pockmarks is characterized by lower sulfate and higher dissolved carbon concentrations as compared to areas of the seafloor where such structures are absent. This is due to the outflow of groundwater, which was confirmed by lower chloride concentration. In addition, sulfate is used to oxidize methane diffusing from deeper layers. Sediments in pockmarks are enriched in Fe(II) carbonates and depleted in Fe(III) (oxy)hydroxides, resulting from the anaerobic oxidation of methane with Fe(III) (Fe-AOM). Ferrous iron produced in large quantities during Fe-AOM is precipitated with carbonates. [ABSTRACT FROM AUTHOR]

Dredged sediment is complex material composed of mineral phases, organics phases, and liquid phases. For the characterization of sediment in the laboratory, the material should be dried before applying some tests, such as the determination of organic matter content, X-ray diffraction (XRD) analysis, X-ray fluorescence (XRF) analysis, specific surface area, specific gravity, and many other tests. To do such tests, in test standards, no specific drying method is recommended. This paper evaluates the effects of drying methods on the measured characteristics of dredged sediment. The drying methods investigated in the current study are oven-drying, freeze-drying, and air drying. From the results obtained, it seems that the drying method affects the results of the test done on the sediment. Among the drying methods, freeze-drying has less effect on sediment properties when the results are compared to a few properties measured on undried material. However, from the point of view of materials classification in road construction, no effects of drying methods are recorded. [ABSTRACT FROM AUTHOR]

Microbial sulfate reduction is generally limited in the deep sea compared to shallower marine environments, but cold seeps and hydrothermal systems are considered an exception. Here, we report sulfate reduction rates and geochemical data from marine sediments and hydrothermal vent fields along the Arctic Mid Ocean Ridges (AMOR), to assess the significance of basalt-hosted hydrothermal activity on sulfate reduction in a distal deep marine setting. We find that cored marine sediments do not display evidence for sulfate reduction, apart from low rates in sediments from the Knipovich Ridge. This likely reflects the overall limited availability of reactive organic matter and low sedimentation rates along the AMOR, except for areas in the vicinity of Svalbard and Bear Island. In contrast, hydrothermal samples from the Seven Sisters, Jan Mayen and Loki's Castle vent fields all demonstrate active microbial sulfate reduction. Rates increase from a few 10s to 100s of pmol SO42- cm-3 d-1 in active hightemperature hydrothermal chimneys, to 10s of nmol SO42- cm-3 d-1 in lowtemperature barite chimneys and up to 110 nmol cm-3 d-1 in diffuse venting hydrothermal sediments in the Barite field at Loki's Castle. Pore fluid and sediment geochemical data suggest that these high rates are sustained by organic compounds from microbial mats and vent fauna as well as methane supplied by high-temperature hydrothermal fluids. However, significant variation was observed between replicate hydrothermal samples and observation of high rates in seemingly inactive barite chimneys suggests that other electron donors may be important as well. Sediment sulfur isotope signatures concur with measured rates in the Barite field and indicate that microbial sulfate reduction has occurred in the hydrothermal sediments since the recent geological past Our findings indicate that basalt-hosted vent fields provide sufficient electron donors to support microbial sulfate reduction in high- and low-temperature hydrothermal areas in settings that otherwise show very low sulfate reduction rates. [ABSTRACT FROM AUTHOR]

Salmon farming in the face of antimicrobial resistance and effects on human health and environment. Abstract: The present review compiles and analyzes studies of the last five years on antibiotic use in the salmon industry, reported effects on fish and humans, and impacts on the environment. There is a growing concern regarding the current management of veterinary therapeutic plans used for the treatment and control of bacterial infections. The main problems are related to the increase of resistance to antibiotics by pathogenic and non-pathogenic bacteria communities, horizontal transfer of resistance genes between bacterial cells, and a major number of cases of failed medical treatments in human and animal populations. Therefore, the challenges for the future will be to reduce dependence on antibiotics in animal production through research into alternatives technologies, the collection of epidemiological information from productive sectors that allow detailed monitoring in the different cultivation phases, biosafety measures from an approach of One Health, and strict supervision in the formulation of medicines by professionals in the animal area. [ABSTRACT FROM AUTHOR]

The observation and analysis of sediment transport in oceans is an important means for the protection of the marine environment, resource development, construction engineering, and element cycling. However, traditional methods of observing sediment transport are either limited by the range of the instruments used or their own observational attributes, such that they cannot be used to accurately detect and analyze the process of transport of marine sediment. A 3D sediment trap has been proposed to compensate for the shortcomings of the various monitoring tools in our team, but no mature method for the analytical inversion of the data obtained from this device has been developed to date. In this paper, we developed analytical methods to invert sediment transport processes using corrected capture efficiency, sample inversion, and transport flux analysis. Through an annular flume test, we measured the turbidity, pressure, and particle size of the water stream and substituted them into the proposed analytical equations, thus verifying the applicability of the analytical methods. We used the slice experiment of the time series of the sediment samples, to determine the validity of the sample inversion, and establish the relationship between the particle size and concentration of the captured samples. We performed restoration tests on the process of sediment transport to establish a set of methods of flux analysis based on the velocity and turbidity of flow. And finally corrected for capture efficiency by particle size. The combination of analytical methods and 3D sediment trap could provide technological support for investigating the evolution of the sea, ecological cycle, and marine engineering. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Mercury (Hg) enrichment relative to total organic carbon (TOC) in sedimentary records has been widely used as a volcanism proxy. However, the depositional and diagenetic effects on Hg burial are not well understood, limiting the reliability of the proxy. Here, we report a systematic investigation of Hg sedimentation under well‐oxygenated bottom water. Most of the studied cores show total mercury content (THg) to TOC ratio between 50 and 300 ppb/%, including northwest Pacific ODP Site 1208, East Equatorial Pacific ODP Sites 677 and 1241, the Antarctic Zone ODP Site 1094, and East China Sea sediment core EC2005. The consistent THg/TOC ratio confirms the strong coupling between Hg and particulate organic matter (POM) despite large differences in geographic locations, sedimentation rates, TOC content, POM sources, and early diagenetic environments. Nevertheless, the THg/TOC ratio is higher in sediments under well‐oxygenated bottom water than in those under oxygen‐depleted waters, probably as a result of a higher degree of organic matter degradation in oxygenated sediments during early diagenesis. The THg in the high TOC variability section at Site 1208 is abnormally high, resulting in decoupling between Hg and POM. Mercury in this section is still leachable by oxidizing solution and has a similar trend of variability with easily reducible iron content, implying that the metal oxide‐organic matter association might act as Hg bounding phase. We suggest that the enriched Hg is probably supplied by the neighboring high TOC sediment. Therefore, while THg/TOC > 300 ppb/% could be considered as distinct Hg enrichment in sedimentary records, the diagenetic mobilization effect should be first excluded as the possible cause as demonstrated by the records of site 1208. Our study therefore provides new insights into the Hg cycle in the modern ocean and the utilization of Hg enrichment as a volcanism proxy.

Abstract Background The soil microbiota has a direct impact on plant development and other metabolic systems, such as the degradation of organic matter and the availability of microelements and metabolites. In the context of agricultural soils, microbial activity is crucial for maintaining soil health and productivity. Thus, the present study aimed to identify, characterize, and quantify the microbial communities of four types of substrates with varying proportions of marine port sediment used for cultivating lemons. By investigating microbial diversity and relative abundance, the work aimed to highlight the importance of soil microbial communities in agriculture when alternative culture media was used. Results The composition and structure of the sampled microbial communities were assessed through the amplification and sequencing of the V3-V4 variable regions of the 16 S rRNA gene The results revealed a diverse microbial community composition in all substrate samples, with a total of 41 phyla, 113 classes, 266 orders, 405 families, 715 genera, and 1513 species identified. Among these, Proteobacteria, Bacteroidota, Planctomycetota, Patescibacteria, Chloroflexi, Actinobacteriota, Acidobacteriota, Verrucomicrobiota, and Gemmatimonadota accounted for over 90% of the bacterial reads, indicating their dominance in the substrates. Conclusions The impact of the substrate origin on the diversity and relative abundace of the microbiota was confirmed. The higher content of beneficial bacterial communities for plant development identified in peat could explain why is considered an ideal agricultural substrate. Development of “beneficial for plants” bacterial communities in alternative agricultural substrates, regardless of the edaphic characteristics, opens the possibility of studying the forced and specific inoculation of these culture media aiming to be agriculturally ideals.

Microbial sulfate reduction is generally limited in the deep sea compared to shallower marine environments, but cold seeps and hydrothermal systems are considered an exception. Here, we report sulfate reduction rates and geochemical data from marine sediments and hydrothermal vent fields along the Arctic Mid Ocean Ridges (AMOR), to assess the significance of basalt-hosted hydrothermal activity on sulfate reduction in a distal deep marine setting. We find that cored marine sediments do not display evidence for sulfate reduction, apart from low rates in sediments from the Knipovich Ridge. This likely reflects the overall limited availability of reactive organic matter and low sedimentation rates along the AMOR, except for areas in the vicinity of Svalbard and Bear Island. In contrast, hydrothermal samples from the Seven Sisters, Jan Mayen and Loki’s Castle vent fields all demonstrate active microbial sulfate reduction. Rates increase from a few 10s to 100s of pmol SO42- cm-3 d-1 in active high-temperature hydrothermal chimneys, to 10s of nmol SO42- cm-3 d-1 in low-temperature barite chimneys and up to 110 nmol cm-3 d-1 in diffuse venting hydrothermal sediments in the Barite field at Loki’s Castle. Pore fluid and sediment geochemical data suggest that these high rates are sustained by organic compounds from microbial mats and vent fauna as well as methane supplied by high-temperature hydrothermal fluids. However, significant variation was observed between replicate hydrothermal samples and observation of high rates in seemingly inactive barite chimneys suggests that other electron donors may be important as well. Sediment sulfur isotope signatures concur with measured rates in the Barite field and indicate that microbial sulfate reduction has occurred in the hydrothermal sediments since the recent geological past. Our findings indicate that basalt-hosted vent fields provide sufficient electron donors to support microbial sulfate reduction in high- and low-temperature hydrothermal areas in settings that otherwise show very low sulfate reduction rates.

Vanadium (V) is a redox-sensitive trace metal that typically exists in one of three oxidation states (+3, +4 and +5) in natural waters; a feature increasingly used in paleoredox studies of ancient marine sediments. However, our knowledge of V geochemistry in low-oxygen marine environments is still limited, especially regarding interactions of V with reduced iron minerals such as green rust. Carbonate green rusts (GR CO3) are mixed FeII/FeIII-phases found in some modern ferruginous settings, such as Lake Matano (Indonesia), and were likely abundant in ancient ferruginous marine systems where they may have played an essential role in authigenic V enrichments in sediments. Here, we present an abiotic pathway of V removal from seawater via reduction and adsorption onto amorphous GR CO3. Suspensions of the freshly precipitated GR CO3 (1 g L−1) were added to vanadate (1 mg VV L−1 initial concentration) in anoxic synthetic seawater solutions. Vanadium removal by GR CO3 was rapid and efficient, with 92 – 99% of V removed in under 20 seconds. Synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy showed that VV adsorbed by GR CO3 was partially reduced to a mixture of VV and VIV, with the average oxidation state of adsorbed V increasing (+4.3 to +4.7) with increasing solution pH (7.5 to 8.5). Upon subsequent exposure to aerated seawater, V-bearing GR CO3 oxidized to lepidocrocite [γ–FeO(OH)] within 24 h, with concomitant reduction of all solid-phase VV to VIV. During oxidation, V was not released back into solution; rather, extended X-ray absorption fine structure (EXAFS) modeling revealed that VIV was structurally incorporated into lepidocrocite as octahedral vanadyl (VO2+). Our work further constrains the aqueous geochemistry of V, which has implications for understanding V cycling and removal mechanisms in both modern and ancient marine systems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Marine sediments act as a sink for the accumulation of various organic contaminants such as polychlorobiphenyls (PCBs). These contaminants affect the composition and activity of microbial communities, particularly favoring those capable of thriving from their biodegradation and biotransformation under favorable conditions. Hence, contaminated environments represent a valuable biological resource for the exploration and cultivation of microorganisms with bioremediation potential. In this study, we successfully cultivated microbial consortia with the capacity for PCB removal under both aerobic and anaerobic conditions. The source of these consortia was a multicontaminated marine sediment collected from the Mar Piccolo (Taranto, Italy), one of Europe's most heavily polluted sites. High-throughput sequencing was employed to investigate the dynamics of the bacterial community of the marine sediment sample, revealing distinct and divergent selection patterns depending on the imposed reductive or oxidative conditions. The aerobic incubation resulted in the rapid selection of bacteria specialized in oxidative pathways for hydrocarbon transformation, leading to the isolation of Marinobacter salinus and Rhodococcus cerastii species, also known for their involvement in aerobic polycyclic aromatic hydrocarbons (PAHs) transformation. On the other hand, anaerobic incubation facilitated the selection of dechlorinating species, including Dehalococcoides mccartyi, involved in PCB reduction. This study significantly contributes to our understanding of the diversity, dynamics, and adaptation of the bacterial community in the hydrocarbon-contaminated marine sediment from one sampling point of the Mar Piccolo basin, particularly in response to stressful conditions. Furthermore, the establishment of consortia with biodegradation and biotransformation capabilities represents a substantial advancement in addressing the challenge of restoring polluted sites, including marine sediments, thus contributing to expanding the toolkit for effective bioremediation strategies. [ABSTRACT FROM AUTHOR]

Protoporphyrin IX (PPIX) serves as a pivotal precursor in the biosynthesis of porphyrins, playing a crucial role in both biological metabolism and biogeochemical cycling. This study investigates the spatial dynamics and co-occurrence patterns of PPIX within the microbial community of marine sediment. The concentrations of PPIX ranged from 7.38 - 91.33 ng/g. Clear patterns in spatiotemporal dynamics in the PPIX were observed, with a more pronounced spatial rather than seasonal variation. Notably, the PPIX and its derivatives in brackish sediment samples exhibited distinct characteristics from those found in saltwater samples. The Spearman test found that PPIX has a positive relationship with chlorophyll-a and pheophytin-a but not with chlorophyll-b or pheophytin-b. Significant positive correlations were identified between PPIX and nitrogen nutrients. Network and variation partitioning analyses highlighted the potential interactions between PPIX and microbial lineages. These findings indicate that PPIX is necessary for microorganisms and widely distributed in sedimentary environments. Additionally, this study underscores the influence of organic matter on microbial community composition and its responsiveness to environmental variations. These insights contribute to a comprehensive understanding of the potential ecological roles of PPIX within natural ecosystems. Protoporphyrin IX is necessary for microorganisms and widely distributed in sedimentary environments. PPIX showed a more pronounced spatial rather than seasonal variation. Porphyrins found in brackish sediment samples exhibited distinct characteristics compared with those present in saltwater samples. Environmental factors can further influence the distribution of porphyrins by affecting microorganisms and their interactions. [ABSTRACT FROM AUTHOR]

Abstract Background Actinomycetes isolated from marine habitats are known to have the potential for novel enzymes that are beneficial in the industry. In-depth knowledge is necessary given the variety of this bacterial group in Indonesia and the lack of published research. Actinomycetes isolates (BLH 5-14) obtained from marine sediments of Sarena Kecil, Bitung, North Sulawesi, Indonesia, showed an ability to produce pectinase and xylanase that have equal or even higher potential for pectic-oligosaccharides (POS) and xylooligosaccharides (XOS) production from raw biomass than from commercial substrates. This study's objective was to characterize both enzymes to learn more for future research and development. Results Pectinase had the highest activity on the 6th day (1.44±0.08 U/mL) at the optimum pH of 8.0 and optimum temperature of 50 °C. Xylanase had the maximum activity on the 6th day (4.33±0.03 U/mL) at optimum pH 6.0 and optimum temperature 60 °C. Hydrolysis and thin layer chromatography also showed that pectinase was able to produce monosaccharides such as galacturonic acid (P1), and xylanase was able to yield oligosaccharides such as xylotriose (X3), xylotetraose (X4), and xylopentaose (X5). BLH 5–14 identified as the genus Streptomyces based on the 16S rDNA sequences and the closely related species Streptomyces tendae (99,78%). Conclusions In the eco-friendly paper bleaching industry, Streptomyces tendae has demonstrated the potential to create enzymes with properties that can be active in a wide range of pH levels. The oligosaccharides have the potential as prebiotics or dietary supplements with anti-cancer properties. Further research is needed to optimize the production, purification, and development of the application of pectinase and xylanase enzymes produced by Actinomycetes isolates.

Bacterial communities in marine sediments of the subtropical Beibu Gulf differ significantly from those of other regions. Thus, it is of great importance to study the marine sediment characteristics comprising bacterial composition, diversity, assembly processes, and functional profile. However, such sediments characteristics in subtropical Beibu Gulf remain unclear. Therefore, we studied the diversity, assembly processes, and functional profiles of the bacterial communities in sediment samples collected from 21 sites in the Beibu Gulf. Upon analysis, Proteobacteria was determined to be the dominant phylum using 16S rRNA sequencing. Predominantly deterministic processes shaped the formation of bacterial communities. The predicted bacterial functional groups involved in the carbon cycle (59.06%) were most abundant in the FAPROTAX database, followed by nitrogen (9.25%) and sulfur (1.01%). Furthermore, the composition of the bacterial community was significantly influenced by TC, TP, and TS (p

The source apportionment of organic carbon is of great scientific significance for understanding the carbon sink pattern in the coastal ocean. The concentrations of total organic carbon (TOC) and total nitrogen (TN) and their isotopic compositions (δ13CTOC and δ15NTN) were determined in surface sediments and sediment cores (Y3 and Y5) collected in the eastern Guangdong coast (EGDC) during spring, summer and winter cruises in 2021, in order to determine the distribution and source of sedimentary organic matter. Spatially, TOC and δ13CTOC distributions in the EGDC have contrasting patterns; TOC concentrations decreased and δ13CTOC values increased with distance offshore. Higher TOC concentrations and enriched δ13CTOC were observed in the marine aquaculture area off EGDC. The measured values of δ13CTOC, δ15NTN and the C/N ratio constrained the two dominant sources of organic matter, marine and terrestrial material, in the EGDC. Using a two end−member mixing model, we estimated the proportion of marine organic matter to be 74 ± 20% in spring, 74 ± 16% in summer and 75 ± 12% in winter, respectively. This suggests in situ production of marine phytoplankton dominated the organic carbon pool (average=~74%) in the EGDC sediment. These consistent marine organic matter contributions are also observed in sediment cores, with proportions averaging 59 ± 5% in core Y3 and 66 ± 4% in core Y5. The observed variations in biogeochemical proxies in sediments are thus mainly caused by differing relative contributions of marine and terrestrial organic matter. Additionally, the high TOC inventory in the marine aquaculture area indicates increased carbon storage and carbon fixation capacity compared to the other areas investigated. Overall, this study establishes a background carbon database in the coastal environment that can be used in future studies of blue carbon to achieve carbon neutrality in China.

Background: The soil microbiota has a direct impact on plant development and other metabolic systems, such as the degradation of organic matter and the availability of microelements and metabolites. In the context of agricultural soils, microbial activity is crucial for maintaining soil health and productivity. Thus, the present study aimed to identify, characterize, and quantify the microbial communities of four types of substrates with varying proportions of marine port sediment used for cultivating lemons. By investigating microbial diversity and relative abundance, the work aimed to highlight the importance of soil microbial communities in agriculture when alternative culture media was used. Results: The composition and structure of the sampled microbial communities were assessed through the amplification and sequencing of the V3-V4 variable regions of the 16 S rRNA gene The results revealed a diverse microbial community composition in all substrate samples, with a total of 41 phyla, 113 classes, 266 orders, 405 families, 715 genera, and 1513 species identified. Among these, Proteobacteria, Bacteroidota, Planctomycetota, Patescibacteria, Chloroflexi, Actinobacteriota, Acidobacteriota, Verrucomicrobiota, and Gemmatimonadota accounted for over 90% of the bacterial reads, indicating their dominance in the substrates. Conclusions: The impact of the substrate origin on the diversity and relative abundace of the microbiota was confirmed. The higher content of beneficial bacterial communities for plant development identified in peat could explain why is considered an ideal agricultural substrate. Development of "beneficial for plants" bacterial communities in alternative agricultural substrates, regardless of the edaphic characteristics, opens the possibility of studying the forced and specific inoculation of these culture media aiming to be agriculturally ideals. [ABSTRACT FROM AUTHOR]

The safe treatment of marine sediment has been a global-scale challenge. To reduce the environmental impacts associated with Portland cement (PC), an environment-friendly binder consisting of quicklime and ground granulated blast-furnace slag (GGBS) was used in the stabilization/solidification of natural marine sediment. Although the combination of lime and GGBS is used to stabilize the sediment with very low water content or moderate water content in previous studies, the natural marine sediment with such a high water content has not been treated by the quicklime–GGBS binder up to now. Therefore, a series of tests were performed to study the physicochemical, mechanical, and microstructural characteristics of quicklime–GGBS stabilized sediments. The results indicated that the quicklime–GGBS solidified/stabilized sediment had a similarly low water content at a proper quicklime-binder ratio to that of PC-stabilized sediments. The pH of quicklime–GGBS solidified sediments gradually decreased as the quicklime-binder ratio decreased and the curing period increased. The unconfined compressive strength (UCS) of quicklime–GGBS stabilized sediments was 1.4 times higher than that of the corresponding PC-stabilized sediments using the same test conditions. The hydration products effectively bonded the sediment particles and filled the pores between the sediment particles, facilitating the improvement of the UCS of the quicklime–GGBS stabilized sediment. The findings indicated that the use of GGBS and a small amount of quicklime can replace PC to stabilize natural marine sediment with high water content. This would be to provide binder dosage and component proportion for the field application of quicklime–GGBS binder and to significantly improve the economical and environmental effects of the treatment of high water content sediment. Innovative lime-activated GGBS is used as a binder in the improvement of sediment with ultrahigh water content. The water content, pH, and UCS of lime–GGBS stabilized sediments are contrastively studied. The engineering performances of lime-GGBS stabilized sediments are better than those of PC-stabilized sediment. An optimal and appropriate lime-binder ratio is suggested. Microstructure mechanism of lime–GGBS stabilized sediment is revealed through series of micro-tests. [ABSTRACT FROM AUTHOR]

Organic carbon (OC) burial efficiency, which relates the OC burial rate to respiration in the seafloor, is a critical parameter in the reconstruction of past marine primary productivities. The current accepted theory is that sediments underlying oxygen-deficient (anoxic) bottom waters have low respiration rates and high OC burial efficiencies. By combining novel in situ measurements in anoxic basins with reaction-transport modelling, we demonstrate that sediments underlying anoxic bottom waters have much higher respiration rates than commonly assumed. A major proportion of the carbon respiration is concentrated in the top millimeter—the so-called 'reactive surface layer'—which is likely a feature in approximately 15% of the coastal seafloor. When re-evaluating previously published data in light of our results, we conclude that the impact of bottom-water anoxia on OC burial efficiencies in marine sediments is small. Consequently, reconstructions of past marine primary productivity in a predominantly anoxic ocean based on OC burial rates might be underestimated by up to an order of magnitude. [ABSTRACT FROM AUTHOR]