Nitrifier adaptation to low energy flux controls inventory of reduced nitrogen in the dark ocean.

Ammonia oxidation to nitrite and its subsequent oxidation to nitrate provides energy to the two populations of nitrifying chemoautotrophs in the energy-starved dark ocean, driving a coupling between reduced inorganic nitrogen (N) pools and production of new organic carbon (C) in the dark ocean. However, the relationship between the flux of new C production and the fluxes of N of the two steps of oxidation remains unclear. Here, we show that, despite orders-of-magnitude difference in cell abundances between ammonia oxidizers and nitrite oxidizers, the two populations sustain similar bulk N-oxidation rates throughout the deep waters with similarly high affinities for ammonia and nitrite under increasing substrate limitation, thus maintaining overall homeostasis in the oceanic nitrification pathway. Our observations confirm the theoretical predictions of a redox-informed ecosystem model. Using balances from this model, we suggest that consistently low ammonia and nitrite concentrations are maintained when the two populations have similarly high substrate affinities and their loss rates are proportional to their maximum growth rates. The stoichiometric relations between the fluxes of C and N indicate a threefold to fourfold higher C-fixation efficiency per mole of N oxidized by ammonia oxidizers compared to nitrite oxidizers due to nearly identical apparent energetic requirements for C fixation of the two populations. We estimate that the rate of chemoautotrophic C fixation amounts to ∼1 × 1013 to ∼2 × 1013 mol of C per year globally through the flux of ∼1 × 1014 to ∼2 × 1014 mol of N per year of the two steps of oxidation throughout the dark ocean.

Integrating Multi-Heterointerfaces in a 1D@2D@1D Hierarchical Structure via Autocatalytic Pyrolysis for Ultra-Efficient Microwave Absorption Performance.

Developing microwave absorption (MA) materials with ultrahigh efficiency and facile preparation method remains a challenge. Herein, a superior 1D@2D@1D hierarchical structure integrated with multi-heterointerfaces via self-assembly and an autocatalytic pyrolysis is designed to fully unlock the microwave attenuation potential of materials, realizing ultra-efficient MA performance. By precisely regulating the morphology of the metal organic framework precursor toward improved impedance matching and intelligently integrating multi-heterointerfaces to boosted dielectric polarization, the specific return loss value of composites can be effectively tuned and optimized to -1002 dB at a very thin thickness of 1.8 mm. These encouraging achievements shed fresh insights into the precise design of ultra-efficient MA materials.

Formic Acid of ppm Enhances LC-MS/MS Detection of UV Irradiation-Induced DNA Dimeric Photoproducts.

Cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs) are genotoxic DNA lesions and mainly generated on thymine-thymine (T-T) dinucleotides upon UV irradiation. Regarding the sensitivity, specificity, and accuracy of analytical methods, it is of first choice to develop a reliable assay for simultaneous detection of these DNA lesions using liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, the dilemma is the low detection sensitivity of the phosphate-containing dimeric photoproducts even using most favorable negative-ion mode for LC-MS/MS analysis. Unexpectedly, we observed that the detection sensitivity of T-T CPD and 6-4PP could be significantly improved using formic acid/acetic acid (∼ppm) as an additive of the mobile phase for reversed-phase LC-MS/MS analysis. This is the first demonstration of the enhancement of LC-MS/MS signals by formic acid/acetic acid in negative-ion mode. Of note, these acidic agents are often used for positive-ion mode in LC-MS assays. Benefited from the developed method, we could quantify both T-T CPD and 6-4PP in mouse embryonic stem cells upon UVC irradiation at low dosage. This sensitive method is applicable to the screening and identification of genes involved in formation, signaling, and repair of UV lesion.

Synthesis and Toxicity of Halogenated Bisphenol Monosubstituted-Ethers: Establishing a Library for Potential Environmental Transformation Products of Emerging Contaminant.

As an important branch of halogenated bisphenol compounds, the halogenated bisphenol monosubstituted-ether compounds have received a lot of attention in environmental health science because of their toxicity and variability. In this study, a synthetic method for bisphenol monosubstituted-ether byproduct libraries was developed. By using the versatile and efficient method, tetrachlorobisphenol A, tetrabromobisphenol A, and tetrabromobisphenol S monosubstituted alkyl-ether compounds were accessed in 39-82 % yield. Subsequently, the cytotoxicity of 27 compounds were screened using three different cell lines (HepG2, mouse primary astrocytes and Chang liver cells). Compound 2,6-dibromo-4-[3,5-dibromo-4-(2-hydroxyethoxy)benzene-1-sulfonyl]phenol was more toxic than other compounds in various cells, and the sensitivity of this compound to the normal hepatocytes and cancer cells was inconsistent. The compounds 2,6-dichloro-4-(2-{3,5-dichloro-4-[(prop-2-en-1-yl)oxy]phenyl}propan-2-yl)phenol and 2,6-dibromo-4-(2-{3,5-dibromo-4-[(prop-2-en-1-yl)oxy]phenyl}propan-2-yl)phenol were the most toxic to HepG2 cells, and most of the other compounds inhibited cell proliferation. Moreover, typical compounds were also reproductive and developmental toxic to zebrafish embryos at different concentrations. The synthetic byproduct libraries could be used as pure standard compounds and applied in research on environmental behavior and the transformation of halogenated flame retardants.

Seohaeicola westpacificensis sp. nov., a novel member of genera Seohaeicola isolated from deep West Pacific Sea water.

Strain JL2247(T), an aerobic, Gram-negative, gliding motile bacterium, was isolated from the western Pacific at the depth of 2,000 m. The cell was spindle-shaped with two narrow poles, and flagella were not observed. The colony was circular, translucent, and milky. This strain showed catalase-positive and oxidase-negative reactions. Its optimal growth conditions were at 32 °C, pH 7.3, and 3 % NaCl. The predominant polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and phosphatidylmonomethylethanolamine. The major fatty acids were summed feature 8 (18:1 w7c and/or 18:1 w6c) and Cyclo C19:0 ω8c and the major respiratory quinone was Q-10. The DNA G+C content of strain JL2247(T) was 72.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain JL2247(T) fell into the genus Seohaeicola, family Rhodobacteraceae, order Rhodobacterales, class Alphaproteobacteria, sharing the highest similarity with the only species Seohaeicola saemankumensis SD-15(T) (96.4 % similarity). From the phenotypic, genotypic, and chemotaxonomic data, strain JL2247(T) represents a novel species of the genus Seohaeicola and the name is proposed as Seohaeicola westpacificensis sp. nov. The type strain is JL2247(T) (=CGMCC 1.12198(T) = JCM18883).

Impacts of eutrophication on microbial community structure in sediment, seawater, and phyllosphere of seagrass ecosystems.

Introduction: Seagrass-associated microbial communities play a crucial role in the growth and health of seagrasses. However, like seagrass meadows, seagrass-associated microbial communities are often affected by eutrophication. It remains unclear how eutrophication influences the composition and function of microbial communities associated with different parts of seagrass. Methods: We employed prokaryotic 16S rRNA gene high-throughput sequencing combining microbial community structure analysis and co-occurrence network analysis to investigate variances in microbial community compositions, potential functions and complexities across sediment, seagrass leaves, and seawater within different eutrophic areas of two adjacent seagrass meadows on Hainan Island, China. Results: Our results indicated that microbial diversity on seagrass leaves was significantly lower than in sediment but significantly higher than in seawater. Both sediment and phyllosphere microbial diversity showed no significant difference between the highly eutrophic and less eutrophic sites in each lagoon. However, sediment microbial diversity was higher in the more eutrophic lagoon, while phyllosphere microbial diversity was higher in the less eutrophic lagoon. Heavy eutrophication increased the relative abundance of phyllosphere microorganisms potentially involved in anaerobic metabolic processes, while reducing those responsible for beneficial functions like denitrification. The main factor affecting microbial diversity was organic carbon in seawater and sediment, with high organic carbon levels leading to decreased microbial diversity. The co-occurrence network analysis revealed that heavy eutrophication notably reduced the complexity and internal connections of the phyllosphere microbial community in comparison to the sediment and seawater microbial communities. Furthermore, ternary analysis demonstrated that heavy eutrophication diminished the external connections of the phyllosphere microbial community with the sediment and seawater microbial communities. Conclusion: The pronounced decrease in biodiversity and complexity of the phyllosphere microbial community under eutrophic conditions can lead to greater microbial functional loss, exacerbating seagrass decline. This study emphasizes the significance of phyllosphere microbial communities compared to sediment microbial communities in the conservation and restoration of seagrass meadows under eutrophic conditions.

Tuning interlayer stacking of 2D covalent organic frameworks for high-resolution separation of C8 aromatic isomers.

Covalent organic frameworks (COFs) has shown great potential as stationary phase in gas chromatography separation. However, designing COF stationary phases with high separation performance remains challenging. Here, we report a novel strategy to enhance the separation ability of COF stationary phases through tuning the interlayer stacking of COF. A rare interlayer modulation of 2D COFs from eclipsed-AA to slipped-AA was achieved through a two-step synthesis method. Simply changing the solvent used in step 1 allowed an interlayer modulation from slipped-AA to eclipsed-AA. As the proof-of-concept, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (Tph) and 2,5-dihydroxyterephthalaldehyde (DHTA) were condensed to prepare 2D COF Tph-DHTA. The interlayer stacking of the 2D COF Tph-DHTA was tuned from eclipsed-AA model to slipped-AA by changing the solvent from o-dichlorobenzene + n-butanol (3:1, v/v) to tetrahydrofuran + n-butanol (1:7, v/v) in step 1. The as-prepared Tph-DHTA with slipped-AA stacking (s-Tph-DHTA) showed higher resolution and faster separation of C8 aromatic isomers than that with eclipsed-AA stacking (e-Tph-DHTA). The formation of slipping stacking of s-Tph-DHTA facilitated the thermodynamics, but did not affect the mass transfer resistance for the separation of C8 aromatic isomers. This work not only provides a promising way to modulate the stacking structure of COFs, but also opens a new strategy to design COF stationary phases for the separation of intractable isomers.

Euryhalocaulis caribicus gen. nov., sp. nov., a new member [corrected] of the family Hyphomonadaceae isolated from the Caribbean Sea.

A new aerobic, Gram-negative, chemo-organotrophic, euryhaline bacterium, designated strain JL2009(T), was isolated from surface water of the Caribbean Sea. The strain formed flaxen colonies on marine ager 2216 (MA; Difco) medium. Cells were dimorphic, with stalks or a polar flagellum, and reproduction occurred by means of binary fission. Growth occurred at 15-45 °C (optimum at 35 °C), 0-15 % (w/v) NaCl (optimum at 1-10 %) and pH 5-9 (optimum at pH 7-8). Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain formed a distinct evolutionary lineage within the family Hyphomonadaceae. Strain JL2009(T) was most closely related to Maricaulis parjimensis MCS 25(T) (92.2 % DNA sequence similarity), Woodsholea maritime CM2243(T) (90.9 %), and Oceanicaulis alexandrii C116-18(T) (90.9 %). The major respiratory quinone was Q-10. The dominant cellular fatty acids were summed feature 8 (C(18:1) ω7c), C(18:0) and 11-methyl C(18:1) ω7c. The polar lipid pattern indicated the presence of phospholipid, phosphatidyl glycerol and glycolipids. The G + C content of the genomic DNA was 70.5 mol%. On the basis of the chemotaxonomic and phenotypic characteristics and the phylogenetic evidence, strain JL2009(T) represents a novel genus and species in the family Hyphomonadaceae, for which the name Euryhalocaulis caribicus gen. nov., sp. nov. is proposed. The type strain of Euryhalocaulis caribicus is JL2009(T) (=CGMCC 1.12036(T) = JCM 18163(T)).

General Two-Step Method for the Fabrication of Covalent-Organic Framework-Bound Open-Tubular Capillary Columns for High-Resolution Gas Chromatography Separation of Isomers.

Covalent organic frameworks (COFs) are promising as stationary phases for gas chromatography (GC). The successful anchoring of COFs to the inner walls of the capillary with good uniformity is an important prerequisite to ensure the excellent separation performance of columns. However, current methods for the fabrication of COF-based capillary columns cannot always meet this requirement when faced with different COFs, which hampers the further development of COF-based GC stationary phases. Here, we show a general two-step method for the fabrication of COF-bound capillary column. The first step enables the formation of uniform amorphous polymer layer on the inner walls of capillary, while the second step allows the facile transformation of the amorphous polymer layer into a highly crystalline COF layer. COF-bound capillary columns with different framework structures were fabricated successfully by the developed two-step method. Impressively, the COF layers bound on the inner walls of these capillary columns showed good uniformity and high crystallinity. More importantly, as an example, the fabricated Tab-DHTA-bound capillary column showed good resolution (R > 1.5) and high column efficiency (700-39,663 plates m-1) for the tested isomers of ethylbenzene, xylene, dichlorobenzene, chlorotoluene, pinene, 1,3-dichloropropene, and propylbenzene with good precision (RSD, run-to-run, n = 5) (retention time, 0.2-0.6%; peak area, 0.5-1.1%; and peak height, 0.5-1.4%). In general, the fabricated Tab-DHTA-bound capillary column exhibited better performance for the separation isomers than commercial columns DB-5 and HP-FFAP. These results indicate that the two-step method is an efficient way to fabricate the COF-bound capillary column with excellent separation performance.

Strategies of chemolithoautotrophs adapting to high temperature and extremely acidic conditions in a shallow hydrothermal ecosystem.

BACKGROUND: Active hydrothermal vents create extreme conditions characterized by high temperatures, low pH levels, and elevated concentrations of heavy metals and other trace elements. These conditions support unique ecosystems where chemolithoautotrophs serve as primary producers. The steep temperature and pH gradients from the vent mouth to its periphery provide a wide range of microhabitats for these specialized microorganisms. However, their metabolic functions, adaptations in response to these gradients, and coping mechanisms under extreme conditions remain areas of limited knowledge. In this study, we conducted temperature gradient incubations of hydrothermal fluids from moderate (pH = 5.6) and extremely (pH = 2.2) acidic vents. Combining the DNA-stable isotope probing technique and subsequent metagenomics, we identified active chemolithoautotrophs under different temperature and pH conditions and analyzed their specific metabolic mechanisms. RESULTS: We found that the carbon fixation activities of Nautiliales in vent fluids were significantly increased from 45 to 65 °C under moderately acidic condition, while their heat tolerance was reduced under extremely acidic conditions. In contrast, Campylobacterales actively fixed carbon under both moderately and extremely acidic conditions under 30 - 45 °C. Compared to Campylobacterales, Nautiliales were found to lack the Sox sulfur oxidation system and instead use NAD(H)-linked glutamate dehydrogenase to boost the reverse tricarboxylic acid (rTCA) cycle. Additionally, they exhibit a high genetic potential for high activity of cytochrome bd ubiquinol oxidase in oxygen respiration and hydrogen oxidation at high temperatures. In terms of high-temperature adaption, the rgy gene plays a critical role in Nautiliales by maintaining DNA stability at high temperature. Genes encoding proteins involved in proton export, including the membrane arm subunits of proton-pumping NADH: ubiquinone oxidoreductase, K+ accumulation, selective transport of charged molecules, permease regulation, and formation of the permeability barrier of bacterial outer membranes, play essential roles in enabling Campylobacterales to adapt to extremely acidic conditions. CONCLUSIONS: Our study provides in-depth insights into how high temperature and low pH impact the metabolic processes of energy and main elements in chemolithoautotrophs living in hydrothermal ecosystems, as well as the mechanisms they use to adapt to the extreme hydrothermal conditions. Video Abstract.

Seismic Response of Star-Type Grid Concrete Wall Structure by Numerical Modeling.

Cement polystyrene shell mold (CPSM) grid concrete walls have been widely applied in the construction of low and mid-rise buildings with higher load-bearing and insulation properties. A star-type grid concrete wall was constructed based on the infill wall simplified to an equivalent diagonal bracing model. To investigate the seismic responses and behavior of a star-type grid concrete wall structure, an overall time-history numerical simulation was carried out in this paper. Typical results, including acceleration, deformation, hysteresis curve and failure pattern of this novel construction system, were interpreted. Results indicate that the star-type grid concrete wall structure has satisfactory seismic performance, including energy dissipation capacity. The structure has higher lateral stiffness and can work in an elastic state under major earthquakes. Accordingly, it is more sensitive to near-fault ground motion with higher frequency components. Meanwhile, the structural inter-story drift angle is less than the limit value of lighter damage when subjected to a super-major earthquake, and the structure presents shear deformation. The openings significantly affect the failure mode, the star-type grid concrete wall with a window (a small aspect ratio less than 1.11) conforms to shear failure, and the wall with a door (aspect ratio of 2.5) conforms to bending-shear failure. The diagonal bracing can distribute the stress in the wall, especially the concrete lattice beam, and effectively resist the lateral forces via the concrete lattice column, improving the ductility and integrity of the structural system.

Substrate regulation leads to differential responses of microbial ammonia-oxidizing communities to ocean warming.

In the context of continuously increasing anthropogenic nitrogen inputs, knowledge of how ammonia oxidation (AO) in the ocean responds to warming is crucial to predicting future changes in marine nitrogen biogeochemistry. Here, we show divergent thermal response patterns for marine AO across a wide onshore/offshore trophic gradient. We find ammonia oxidizer community and ambient substrate co-regulate optimum temperatures (Topt), generating distinct thermal response patterns with Topt varying from ≤14 °C to ≥34 °C. Substrate addition elevates Topt when ambient substrate is unsaturated. The thermal sensitivity of kinetic parameters allows us to predict responses of both AO rate and Topt at varying substrate and temperature below the critical temperature. A warming ocean promotes nearshore AO, while suppressing offshore AO. Our findings reconcile field inconsistencies of temperature effects on AO, suggesting that predictive biogeochemical models need to include such differential warming mechanisms on this key nitrogen cycle process.

Differential incorporation of one-carbon substrates among microbial populations identified by stable isotope probing from the estuary to South China Sea.

Methanol (MOH) and monomethylamine (MMA) are two typical one-carbon (C1) compounds found in natural environments. They play an important role in marine and atmospheric chemistry, cloud formation, and global climate. The main biological sink of MOH and MMA is rapid consumption by marine microbes. Here, field-based time-series incubations with supplemental 13C-labelled MOH and MMA and isotope ratio analyses were performed. A substantial difference in the MOH and MMA incorporation rates and bacterial taxa were observed between the South China Sea (SCS) and the Pearl River estuary. C1 substrates were assimilated more quickly in the estuary than the SCS shelf where MOH and MMA had similar bio-availability. However, microbial responses to MMA may be faster than to MOH in the coastal and basin surface water of the SCS despite similar active bacterial populations. Three ecological types of bacteria, in terms of response to supplemented MOH and MMA, were identified: rapid incorporation (I, dominant C1-incorporating group), slow incorporation (II, minor C1-incorporating group), and no incorporation (III, C1-non-incorporating group). Members of the families Methylophilaceae (ß-Proteobacteria) and Piscirickettsiaceae (γ-Proteobacteria) belonged to type I and actively incorporated substrates in the estuary and SCS, respectively. Diverse MOH and MMA-incorporating type II bacteria were identified by stable isotope probing in the SCS, and could play a more important role in the transformation of C1 compounds in marine environments than hitherto assumed.

Differential Incorporation of Carbon Substrates among Microbial Populations Identified by Field-Based, DNA Stable-Isotope Probing in South China Sea.

To determine the adapted microbial populations to variant dissolved organic carbon (DOC) sources in the marine environment and improve the understanding of the interaction between microorganisms and marine DOC pool, field-based incubation experiments were carried out using supplemental 13C-labeled typical substrates D-glucose and D-glucosamine (D-Glc and D-GlcN, respectively), which are two important components in marine DOC pool in the South China Sea. 13C- and 12C-DNA were then fractionated by ultracentrifugation and the microbial community was analyzed by terminal-restriction fragment length polymorphism and 454 pyrosequencing of 16S rRNA gene. 12C-DNA-based communities showed relatively high similarities with their corresponding in situ communities, and their bacterial diversities were generally higher than 13C-DNA-based counterparts. Distinct differences in community composition were found between 13C- and 12C-DNA-based communities and between two substrate-supplemented 13C-DNA-based communities; these differences distinctly varied with depth and site. In most cases, there were more genera with relative abundances of >0.1% in D-Glc-incorporating communities than in D-GlcN-incorporating communities. The Roseobacter clade was one of the prominent actively substrate-incorporating bacterial populations in all 13C-DNA-based communities. Vibrio was another prominent actively D-GlcN-incorporating bacterial population in most incubations. However notably, different OTUs dominated this clade or genus in different treatments at different depths. Altogether, these results suggested that there were taxa-specific differences in DOC assimilations and, moreover, their differences varied among the typical water masses, which could have been caused by the variant compositions of original bacterial communities from different hydrological environments. This implies that ecologically, the levels of labile or recalcitrance of DOC can be maintained only in a specific environmental context with specific bacterial community composition.

Magnetic solid phase extraction coupled with inductively coupled plasma mass spectrometry for the speciation of mercury in environmental water and human hair samples.

In this work, γ-mercaptopropyltrimethoxysilane (γ-MPTS) modified Fe3O4@SiO2 magnetic nanoparticles (MNPs) was successfully prepared, and characterized by Fourier transform infrared spectrometer (FT-IR), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM). The sorption performance of the prepared Fe3O4@SiO2@γ-MPTS MNPs towards methylmercury (CH3Hg(+)) and inorganic mercury (Hg(2+)) was investigated. It was found that CH3Hg(+) and Hg(2+) could be simultaneously retained on the prepared Fe3O4@SiO2@γ-MPTS MNPs, and the quantitative elution of CH3Hg(+) and total mercury (THg) was achieved by using 1.5 mol L(-1) HCl containing 0.01% and 3% thiourea (m/v), respectively. And the levels of Hg(2+) were obtained by subtracting CH3Hg(+) from THg. Based on the above facts, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the speciation of CH3Hg(+) and Hg(2+). Various experimental parameters affecting MSPE of CH3Hg(+) and Hg(2+) such as pH, eluent, sample volume, and co-existing ions have been studied. Under the optimized conditions, the limits of detection (LODs) for CH3Hg(+) and THg were 1.6 and 1.9 ng L(-1), respectively. The accuracy of the proposed method was validated by analysis of a Certified Reference Material NRCC DORM-2 dogfish muscle, and the determined values are in good agreement with the certified values. The proposed method has also been successfully applied for the speciation of CH3Hg(+) and Hg(2+) in environmental water and human hair samples.

Draft Genome Sequence of Euryhalocaulis caribicus Strain JL2009T, a New Member of the Family Hyphomonadaceae Isolated from the Caribbean Sea.

Euryhalocaulis caribicus strain JL2009(T) is a novel genus and species of the family Hyphomonadaceae and was first isolated from surface water in the Caribbean Sea. Here, we report the first draft genome from this genus. Its genome contains genes encoding proteins that are involved in organic acid metabolism and probable low-affinity inorganic phosphate transporters, which suggests its competence in oligotrophic oceans.