Search Results (71)

The Southeastern Tyrrhenian Sea is a back-arc basin characterized by the onset of volcanism over the past ~11 million years and the development of numerous volcanic seamounts. Hydrothermal venting is predominantly concentrated in the southeastern sector, encompassing the Aeolian volcanic arc and major volcanic edifices, such as Palinuro and Marsili. These systems frequently exhibit zones of localized magnetic depletion (demagnetization) within otherwise magnetized volcanic structures, often linked to hydrothermal alteration. Notably, volcanic rejuvenation phases are commonly associated with active hydrothermal circulation. In response to mounting ecological concerns, the Italian government has delineated extensive Ecological Protection Zones (EPZs), including those in the Eastern Tyrrhenian sector. These EPZs encompass a series of prominent seamounts—Palinuro, Marsili, Vercelli, Vavilov, Magnaghi, Enarete, and Anchise—that exhibit morphological evidence of rejuvenation and magnetic anomalies consistent with hydrothermal modification. Such features are indicative of potentially mineralized systems, relevant for future resource exploration. A comprehensive evaluation of both the ecological significance and the mineral potential of these areas is now imperative. Balancing environmental conservation with the strategic assessment of deep-sea mining prospects will be essential to mitigate biodiversity loss while promoting the sustainable use of marine mineral resources. Full article

Importance of this study: Melanin synthesized through the oxidative polymerization of phenolic compounds exhibits a high molecular weight and has many physiological functions and activities. Main results: In this study, the key PKS1-1, PKS1-2, CMR1-1, and CMR1-2 genes for melanin biosynthesis and regulation from the highly genome-duplicated black yeast Hortaea werneckii Mo34, isolated from a deep-sea hydrothermal vent, were heterologously complemented in the ∆pks1 albino mutant K5 and the ∆cmr1 albino mutant CM7-2 of Aureobasidium melanogenum XJ5-1. Melanin formation in all the resulting transformants was restored, confirming that both the PKS1-1 and PKS1-2 genes from H. werneckii Mo34 were likely involved in the DHN melanin biosynthesis of A. melanogenum XJ5-1. Furthermore, the CMR1-1 and CMR1-2 genes from H. werneckii Mo34 could play significant roles in regulating melanin biosynthesis in A. melanogenum XJ5-1. Simultaneously, the expression of the PKS1 and THR1 genes involved in melanin biosynthesis was also enhanced in the transformants complemented with the CMR1-1 and CMR1-2 genes. The purified high-molecular-weight melanin from H. werneckii Mo34 exhibited excellent Fe²⁺-chelating, DPPH radical-scavenging, and superoxide radical-scavenging activities. Additionally, it actively inhibited the growth of Staphylococcus aureus and Pseudomonas putida. Conclusions: The black yeast H. werneckii Mo34 indeed had the DHN melanin biosynthesis pathway and the melanin produced by it had many potential applications. Full article

Deep-sea chemosynthetic ecosystems, including cold seeps and hydrothermal vents, are widely spread in global oceans. Campylobacterota are important primary producers in deep-sea hydrothermal vents and serve as a vital food source for local invertebrates. However, the nutrients that these bacteria can provide to their hosts are unclear. To date, research on Campylobacterota in cold seeps is very limited. Consequently, little is known about the biological features and ecological potential of Campylobacterota in cold seeps. In the present work, we examined the diversity, growth, metabolic characteristics, and nutrient production of Campylobacterota in a deep-sea cold seep. Over 1000 Campylobacterota ASVs, especially autotrophic Sulfurovum and Sulfurimonas, were identified. By optimizing the culture medium, 9 Sulfurovum and Sulfurimonas strains were isolated, including three potentially novel species. Two novel species were characterized and found to exhibit unique morphological features. These two novel strains possessed complete reverse tricarboxylic acid pathways. One novel strain, FCS5, was a psychrotolerant autotroph with denitrification and phosphorus-removing capacity. FCS5 could grow in the absence of vitamins. Consistently, metabolomics and transcriptome analyses indicated that FCS5 produced multiple vitamins, which regulated the expressions of a large number of genes associated with carbon fixation and multiple-nutrient synthesis. Besides vitamins, autotrophic Campylobacterota also produced abundant free amino acids, fatty acids (short-chain, medium, and long-chain), and proteins. This study indicates that the cold seep abounds with Campylobacterota, which are capable of providing various nutrients for the chemosynthetic ecosystem. In addition, these bacteria may have wide applications, such as in wastewater treatment and carbon emission reduction. Full article

The weathering of seafloor hydrothermal sulfides is facilitated by microbial activities, yet the specific mechanisms of different sulfide types are not well understood. Previous studies have primarily been carried out under laboratory conditions, making it difficult to accurately replicate the complex in situ conditions of deep-sea hydrothermal fields. Herein, we deployed two well-characterized pyrite (Py)-dominated and chalcopyrite (Ccp)-dominated sulfide slices, which were placed 300 m from an active venting site in the Wocan-1 hydrothermal field (Carlsberg Ridge, Northwest Indian Ocean) for an 18-month in situ incubation experiment. Microscopic observations and organic matter analyses were conducted on the recovered sulfide slices to investigate the microbial weathering features of different sulfide types. Our results demonstrated that the weathering of the Py-dominated sulfide sample was primarily mediated by extracellular polymeric substances (EPSs) through indirect interactions, whereas the Ccp-dominated sulfide sample exhibited both direct microbial dissolution, resulting in the formation of distinct dissolution pits, and indirect EPS-mediated interactions. Four distinct phases of microbe–sulfide interactions were identified: approach, adsorption, stable attachment, and extensive colonization. Furthermore, the weathering products and biomineralization structures differed significantly between the two sulfide types, reflecting their different microbial colonization processes. Our study confirms that microorganisms are crucial in seafloor sulfide weathering. These findings advance our understanding of microbial-driven processes in sulfide mineral transformations and their role in marine ecosystems. Our findings are also valuable for future research on biogeochemical cycles and for developing bioremediation strategies for deep-sea mining. Full article

Sulfation plays a critical role in the biosynthesis of small molecules, regulatory mechanisms such as hormone signaling, and detoxification processes (phase II enzymes). The sulfation reaction is catalyzed by a broad family of enzymes known as sulfotransferases (SULTs), which have been extensively studied in animals due to their medical importance, but also in plant key processes. Despite the identification of some sulfated metabolites in fungi, the mechanisms underlying fungal sulfation remain largely unknown. To address this knowledge gap, we conducted a comprehensive search of available genomes, resulting in the identification of 174 putative SULT genes in the Ascomycota phylum. Phylogenetic analysis and structural modeling revealed that these SULTs belong to the aryl sulfotransferase family, and they are divided into two potential distinct clusters of PAPS-dependent SULTs within the fungal kingdom. SULT genes from two marine fungi isolated from deep-sea hydrothermal vents, Hortaea werneckii UBOCC-A-208029 (HwSULT) and Aspergillus sydowii UBOCC-A-108050 SULT (AsSULT), were selected as representatives of each cluster. Recombinant proteins were expressed in Escherichia coli and biochemically characterized. HwSULT demonstrated high and versatile activity, while AsSULT appeared more substrate-specific. Here, HwSULT was used to sulfate the mycotoxin zearalenone, enhancing its cytotoxicity toward healthy feline intestinal cells. Full article

The mixing of hydrothermal vent fluids with deep ocean water and near-vent pelagic matter results in particle populations with a complex composition consisting of hydrothermally derived, rock-forming, and biogenic particles. This study is the first investigation of deep sediment trap material collected at the Jan Mayen hydrothermal vent field area at 71° N and 6° W of the southernmost Mohns Ridge in the Norwegian–Greenland Sea. This area is characterized by high magmatic activity, axial volcanic ridges, and mafic-hosted volcanogenic massive sulfide deposits. Data on sinking particle fluxes from two hydrothermal settings, the Troll Wall and Soria Moria vent fields, located about 4 km apart, are discussed in the article. In particular, the study emphasize the differences between two hydrothermal settings from each other that demonstrate the geodiversity of hydrothermal processes within the relatively shallow Jan Mayen hydrothermal vent field area affected by the Iceland and Jan Mayen hotspots. The fluxes of sinking hydrothermally derived particles (barite, gypsum, non-crystalline Fe-Si oxyhydroxides, and Fe, Zn, and Cu sulfides) obtained at the Jan Mayen hydrothermal vents made it possible to elucidate the characteristic features of their buoyancy plumes and compare them with similar data reported for other submarine hydrothermal systems. In terms of the composition of the deep-sea hydrothermal particles from buoyant plumes, the studied vent fields are most similar to the Menez Gwen and Lucky Strike vent fields affected by the Azores hotspot. The supply of hydrothermally derived matter is accompanied by normal pelagic/hemipelagic sedimentation, which is dominated by biogenic particles, especially in the upper water layers. Full article

Organisms occupy diverse ecological niches worldwide, each with characteristics finely evolved for their environments. Crustaceans residing in deep-sea hydrothermal vents, recognized as one of Earth’s extreme environments, may have adapted to withstand severe conditions, including elevated temperatures and pressure. This study compares the exoskeletons of two vent crustaceans (bythograeid crab Austinograea sp. and squat lobster Munidopsis lauensis) with four coastal species (Asian paddle crabs, blue crab, hermit crab, and mantis shrimp) to identify traits influenced by vent environments. The goal was to identify distinctive exoskeletal characteristics commonly observed in vent crustaceans, resulting from their exposure to severe abiotic factors, including elevated temperatures and pressures, found in vent environments. Results show that the exoskeletons of vent crustaceans demonstrated significantly enhanced thermal stability compared to coastal species. These vent crustaceans consistently featured exoskeletons characterized by a reduced proportion of volatile components, such as water, and an increased proportion of CaCO₃, compared with coastal crustaceans. Furthermore, vent crustaceans lacked carotenoid pigments that had low heat resistance. However, no apparent differences were observed in the mechanical properties. Our findings suggest that the similar composition of exoskeletons in vent crustaceans evolved convergently to withstand high temperatures. Full article

Large-scale and multi-sample datasets have revealed that microbial diversity and geographic distribution patterns are distinct across various habitats, particularly between hydrothermal vent and cold seep ecosystems. To date, our understanding of the effects of spatial and geochemical gradients on marine microbial communities remains limited. Here, we report the microbial diversity and metabolic versatility of a remote seafloor sediment ecosystem at different sites (GC-2, -4, -5, -6, -8) in the Mid-Okinawa Trough (Mid-OT) using high-throughput metagenomic sequencing technology. Desulfobacteraceae (3.1%) were detected in a high abundance at GC-2 with intense methane concentrations (353 μL/L), which showed a clear correlation with cold seeping. Whereas Candidatus Brocadiaceae (1.7%), Rhodobacteraceae (0.9%), and Rhodospirillaceae (0.7%), which are commonly involved in denitrification and sulfur oxidation, were enriched at GC-8. Concurrently investigating the potential of deep-sea microbial metabolism, we gained insights into the adaptive capabilities and metabolic mechanisms of microorganisms within seafloor environments. Utilizing the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, the analysis of functional modules revealed a significant enrichment (71–74%) of genes associated with metabolic pathways. These results expand our knowledge of the relationship between microbial biodiversity and metabolic versatility in deep-sea extreme environments. Full article

Since the 2005 discovery of the first enzyme capable of depolymerizing polyethylene terephthalate (PET), an aromatic polyester once thought to be enzymatically inert, extensive research has been undertaken to identify and engineer new biocatalysts for plastic degradation. This effort was directed toward developing efficient enzymatic recycling technologies that could overcome the limitations of mechanical and chemical methods. These enzymes are versatile molecules obtained from microorganisms living in various environments, including soil, compost, surface seawater, and extreme habitats such as hot springs, hydrothermal vents, deep-sea regions, and Antarctic seawater. Among various plastics, PET and polylactic acid (PLA) have been the primary focus of enzymatic depolymerization research, greatly enhancing our knowledge of enzymes that degrade these specific polymers. They often display unique catalytic properties that reflect their particular ecological niches. This review explores recent advancements in marine-derived enzymes that can depolymerize synthetic plastic polymers, emphasizing their structural and functional features that influence the efficiency of these catalysts in biorecycling processes. Current status and future perspectives of enzymatic plastic depolymerization are also discussed, with a focus on the underexplored marine enzymatic resources. Full article

Extremophiles, organisms thriving in extreme environments such as hot springs, deep-sea hydrothermal vents, and hypersaline ecosystems, have garnered significant attention due to their remarkable adaptability and biotechnological potential. This review presents recent advancements in isolating and characterizing extremophiles, highlighting their applications in enzyme production, bioplastics, environmental management, and space exploration. The unique biological mechanisms of extremophiles offer valuable insights into life’s resilience and potential uses in industry and astrobiology. Full article

This study investigates taxonomic characteristics of carnivorous sponges from the Southern Ocean. The specimens were collected in 2010 from deep-sea hydrothermal vents of the East Scotia Ridge during the RRS James Cook Cruise JC42. All the investigated sponges are new to science. They belong to the genera Abyssocladia and Cladorhiza within the family Cladorhizidae. This study provides descriptions and remarks for the three new species Abyssocladia truespacemeni, Abyssocladia hendrixii and Cladorhiza elsaae. Comparative faunistic and ecological aspects of these sponge genera within the Southern Ocean sponge fauna are discussed. The genera Abyssocladia and Cladorhiza are recorded here for the first time from the ecosystem around hydrothermal vents in the Antarctic deep sea. The descriptions of new species contribute to and expand the current knowledge of the Cladorhizidae and consequently support future taxonomic identifications and descriptions of Antarctic deep-sea carnivorous sponges. The appearance of these newly discovered species underlines the hypothesis that Cladorhizidae is the second most species-rich family of Demospongiae in the Southern Ocean, and many new species of this deep-sea sponge family are still to be discovered. Full article

Deep-sea hydrothermal vents have been extensively explored around the globe in the past decades, and the diversity of microbial communities and their ecological functions related to hydrothermal vents have become hotspots in the study of microbial biogeochemistry. However, knowledge of dominant microbial communities and their unique metabolic characteristics adapting to hydrothermal vents is still limited. In our study, the sediment sample near the Tangyin hydrothermal vent in the southern part of the Okinawa Trough was collected, and the most abundant phyla are Proteobacteria and Desulfobacterota based on the 16S rRNA genes and metagenome sequencing. Metagenomic analysis revealed that methane metabolism, sulfur reduction, and Fe²⁺ uptake were abundantly distributed in hydrothermal sediment. In addition, most of the metagenomic assembly genomes (MAGs), belonging to Chloroflexota, Desulfobacterota, and Gammaproteobacteria, were found to be involved in methanogenesis, sulfur oxidation/reduction, and ferrous/ferric iron metabolisms. Among these MAGs, the two representative groups (Bathyarchaeia and Thioglobaceae) also showed distinct metabolic characteristics related to carbon, sulfur, and iron to adapt to hydrothermal environments. Our results reveal the dominant microbial populations and their metabolic features in the sediment near the Tangyin hydrothermal fields, providing a better understanding of microbial survival strategies in the extreme environment. Full article

Deep-sea hydrothermal circulation plays a pivotal role in the material and energy exchange in deep-sea environments, exerting significant influence on the evolution of seawater chemistry and global climate dynamics. Based on existing data and assumptions, this study presents a numerical model tailored for the hydrothermal circulation in the Wocan-1 Hydrothermal Field, Carlsberg Ridge, Indian Ocean. The model successfully simulates the hydrothermal circulation patterns within the oceanic crust, providing detailed insights into temperature distribution, flow field structures, and elemental concentration gradients. Through data analysis of the simulation results, we inferred the depth and temperature of potential heat sources within the Wocan-1 hydrothermal field. The maximum temperature of the heat source T_max = 823K (550 °C) and the depth of the heat source h = 1 km are possible results. To deepen understanding of the heat source’s impact on fluid temperatures, a sensitivity analysis was conducted. The findings show a positive correlation between both the heat source’s temperature and its depth with the fluid temperature at vent outlets. Regarding elemental transport, this paper offers a preliminary exploration of the kinetic processes in hydrothermal circulation and presents an empirical relationship linking elemental concentrations at the bottom to those at the vent: C_vent = 0.26 C_boundary. This study enhances current numerical models for hydrothermal vents, offering valuable insights for future work and utilization in the Wocan-1 hydrothermal field, and potentially in any other hydrothermal field. Full article

Xyloplax is a genus of three species of sea stars previously found only on sunken wood in the deep ocean. Their circular and petaloid bodies, which lend them their common name “sea daisy”, and their presumed exclusive diet of wood make them an unusual and rare element of deep-sea ecosystems. We describe here the fourth species of Xyloplax from the eastern Pacific Ocean, Xyloplax princealberti n. sp., which ranges from offshore Canada to the Gulf of California (Mexico) and Costa Rica. Though sampled geographically close to another described species of Xyloplax from the northeastern Pacific, X. janetae, this new species is unique morphologically and according to available DNA data. The short abactinal spines are the most obvious feature that distinguishes X. princealberti n. sp. from other Xyloplax. The minimum distance for mitochondrial cytochrome c oxidase subunit I from Xyloplax princealberti n. sp. to the only other available Xyloplax, X. janetae, was 13.5%. We also describe Ridgeia vestimentiferan tubeworm bushes from active hydrothermal vents as a new Xyloplax habitat, the first record of a non-wood substrate, and a new reproductive strategy, simultaneous hermaphroditism, for this genus. We generated the first mitochondrial genome for a member of Xyloplax and analyzed it with other available asteroid data using nucleotide-coding or amino acid (for protein-coding genes) plus nucleotide coding (for rRNA genes). The nucleotide-coding results place Xylopax as part of the clade Velatida, consistent with a previous phylogenomic analysis that included Xyloplax princealberti n. sp. (as Xyloplax sp.), though the placement of Velatida within Asteroidea differed. The amino acid plus nucleotide coding recovered Velatida to be a grade with X. princealberti n. sp. as sister group to all other Asteroidea. Full article

The snail P. glabra is an endemic species in deep-sea chemosynthetic ecosystems of the Northwest Pacific Ocean. To obtain more genetic information on this species and provide the basis for subsequent whole-genome map construction, a genome survey was performed on this snail from the hydrothermal vent of Okinawa Trough. The genomic size of P. glabra was estimated to be 1.44 Gb, with a heterozygosity of 1.91% and a repeated sequence content of 69.80%. Based on the sequencing data, a draft genome of 1.32 Gb was assembled. Transposal elements (TEs) accounted for 40.17% of the entire genome, with DNA transposons taking the highest proportion. It was found that most TEs were inserted in the genome recently. In the simple sequence repeats, the dinucleotide motif was the most enriched microsatellite type, accounting for 53% of microsatellites. A complete mitochondrial genome of P. glabra with a total length of 16,268 bp was assembled from the sequencing data. After comparison with the published mitochondrial genome of Provanna sp. from a methane seep, 331 potential single nucleotide polymorphism (SNP) sites were identified in protein-coding genes (PCGs). Except for the cox1 gene, nad2, nad4, nad5, and cob genes are expected to be candidate markers for population genetic and phylogenetic studies of P. glabra and other deep-sea snails. Compared with shallow-water species, three mitochondrial genes of deep-sea gastropods exhibited a higher evolutionary rate, indicating strong selection operating on mitochondria of deep-sea species. This study provides insights into the genome characteristics of P. glabra and supplies genomic resources for further studies on the adaptive evolution of the snail in extreme deep-sea chemosynthetic environments. Full article