Phosphate Oxygen Research Articles

12543 Biochemical And Structural Studies Of Human 17-Hydroxysteroid Dehydrogenase Type 1 Mutations Engineered To Convert An NADPH-dependent Reductase To An NAD-dependent Oxidase

Abstract Disclosure: N. Motl: None. K.L. Harris: None. D. Mizrachi: None. R.J. Auchus: None. E. Scott: None. Background: In intact cells, the hydroxysteroid dehydrogenases (HSDs) strongly favor either NADPH-dependent ketosteroid reduction or NAD+-dependent hydroxysteroid oxidation. For ketosteroid reductases, mutation of the arginine 38 residue in the cofactor-binding domain, which forms a salt-bridge with the 2-phosphate of NADP(H), attenuates the reductive preference but does not eliminate NADPH binding. We sought to engineer mutations of human 17βHSD1 that lack NADP(H) binding, analogous to the oxidative HSDs. Methods: Wild-type 17βHSD1 and mutations of L37 and/or R38 in the cofactor-binding domain were expressed in E. coli and purified to homogeneity in one step. The purified proteins were assayed for NAD+- and NADP-dependent estradiol oxidation to measure cofactor affinity. Crystals were grown in the presence of NAD+ and/or estrone, and structures were determined using molecular replacement. Results: For wild-type 17βHSD1, the Km for NAD+ was 7-times higher than for NADP+ (44 vs 6.2 μM, respectively). Mutations R38D and R38I raised the Km for NAD+ < 4-fold but the Km for NADP+ >60-fold to favor NAD+ utilization. For mutations L37D/R38I and L37D/R38D, the Km for NAD+ was 100-120 μM, but NADP+ could not support catalysis at concentrations up to 4 mM. The crystal structures of 17βHSD1, wild-type and mutations R38D or L37D/R38D soaked with NAD+, were solved to 1.79, 1.75, and 1.80 Å, respectively. All structures displayed a near-identical overall fold. While the NAD density for the mutant structures was much weaker than for the wild type enzymes, some differences in NAD positioning were observed. The R38D mutation had minor NAD repositioning. However, in the L37D/R38D structure the NAD cofactor is repositioned slightly further and 37D is angled towards the cofactor, rather than away from it as observed in the other structures. The positively-charged R38 which interacts with the NADP phosphate oxygen in the wild type enzyme (PDB: 1QYV) is lost in both mutants. Instead the oxygen atoms of both mutated residues orient towards where the cofactor phosphate oxygen would be present, likely interfering with NADP binding and contributing to the observed switch of cofactor preference. Conclusion: Mutation of L37D combined with a second, hydrophobic or negatively-charged substitution at R38 precluded NADP(H) binding and converted 17βHSD1 to a purely oxidative HSD similar to 17βHSD2. NADP(H) exclusion in the L37D/R38D mutant appears to be due to 1) loss of the phosphate-R38 interaction and 2) the position and negatively charged character of oxygen atoms of 37D/38D conflicting with positioning of the positively charged NADP phosphate. Keywords: hydroxysteroid dehydrogenase, nicotinamide cofactor, estrogen, x-ray crystallography Presentation: 6/2/2024

Phosphorus Cycling in Intertidal Zones with Submarine Groundwater Discharge: Insights from Time-Integrated Phosphate Oxygen Isotope Analyses through Passive Sampling

Phosphorus Cycling in Intertidal Zones with Submarine Groundwater Discharge: Insights from Time-Integrated Phosphate Oxygen Isotope Analyses through Passive Sampling

Influence of Magnesium Ion Binding on the Adenosine Diphosphate Structure and Dynamics, Investigated by 31P NMR and Molecular Dynamics Simulations.

Magnesium (Mg2+) is the most abundant divalent cation in the cell and is essential to nearly every biochemical reaction involving adenosine triphosphate (ATP) and its lower energy counterpart, adenosine diphosphate (ADP). In this work, we examine the solution dynamics of ADP at different concentrations and record the changes thereof due to the presence of Mg2+ ions. Relaxation and diffusion experiments were performed on a range of ADP solutions with increasing magnesium concentration. The most significant changes of both relaxation and diffusion behaviors are observed when adding Mg2+ up to 0.5 ADP equivalent (eq), with most of the changes complete at 1 eq. Molecular dynamics simulations also show a significant structure introduced by Mg2+ with very stable pyramidal coordination with the phosphate oxygens. A more extended structure found in the presence of Mg2+ is consistent with the experimental slowing of diffusion and an increase in the spin-lattice relaxation rate. We do not observe direct evidence of aggregation in solution, although translational diffusion is slowed down significantly at higher concentrations (while solvent diffusion remains constant).

Tracing of fire‐induced soil phosphorus transformations using phosphate oxygen isotope ratio

AbstractThis study demonstrates that phosphate oxygen isotope (δ18OPO4) analysis effectively detects and monitors fire‐induced transformation in soil phosphorus (P). Fires increase bioavailable P, potentially limiting primary production in terrestrial ecosystems. However, understanding the effects of fire on soil P dynamics in the field remains challenging due to the interaction between fire spread and soil properties with high spatial heterogeneity. Soil burning experiments were conducted using a surface soil sample collected in central Japan. The soil was burned in an electric furnace from 50 to 550°C for 3 h, and P concentrations and δ18OPO4 values were determined. The results revealed that high temperatures (>350°C) depleted the soil of organic P (Po) and increased labile and stable inorganic P (Pi) concentrations while significantly decreasing δ18OPO4 values. By contrast, low temperatures (150°C) increased labile Pi and Po concentrations without isotopic shift, indicating that low‐intensity fires could increase bioavailable P while conserving soil organic matter. These findings indicate that δ18OPO4 analysis can provide insight into the relationship between P transformations and fire intensity and track subsequent changes in P dynamics over time. Our research highlights the potential of δ18OPO4 in predicting and managing postfire ecological and agricultural impacts.

Biopolymeric Composite Columns for Improving Water Quality in a Freshwater Stream Receiving Wastewater Treatment Plant Effluents

Inefficiently treated wastewater, which contains a high concentration of pollutants, is hazardous when it is mixed with the clean water of rivers and lakes. Nitrate in particular is a major global problem that leads to eutrophication and poses a threat to both aquatic ecosystems and human health. To address this issue, this work assessed the efficiency of polymeric cryogel (PC) and biopolymer (EPS)-blended composites (EPS@PC) in removing nitrates. Tests were also conducted to quantify the decrease in phosphate, chloride ions, and chemical oxygen demand (COD) in real water samples taken from the Ankara stream, which receives effluents from both urban (UWTP) and industrial (IWTP) wastewater treatment plants. Five different columns with varying adsorptive properties were prepared, some of which were combined with iron. The EPS-@PC-C5 column demonstrated the highest adsorption ratio for nitrate removal compared to the other tested columns. The EPS@PC-C5 achieved a high removal efficiency of 126.38 mg nitrate/g and showed COD reduction ranging from 60.2 to 94.1%. The removal ratio of chloride concentration varied between 56.0 and 75.7%, while the removal of phosphates ranged from 87 to 99%. Columns composed of EPS (EPS@PC) with both negatively and positively charged ligands are dependable and suitable options for water remediation.Graphical

Emerging pollutant in surface water bodies: a review on monitoring, analysis, mitigation measures and removal technologies of micro-plastics.

Water bodies play a crucial role in supporting life, maintaining the environment, and preserving the ecology for the people of India. However, in recent decades, human activities have led to various alterations in aquatic environments, resulting in environmental degradation through pollution. The safety of utilizing surface water sources for drinking and other purposes has come under intense scrutiny due to rapid population growth and industrial expansion. Surface water pollution due to micro-plastics (MPs) (plastics < 5mm in size) is one of the emerging pollutants in metropolitan cities of developing countries because of its utmost resilience and synthetic nature. Recent studies on the surface water bodies (river, pond, Lake etc.) portrait the correlation between the MPs level with different parameters of pollution such as specific conductivity, total phosphate, and biological oxygen demand. Fibers represent the predominant form of MPs discovered in surface water bodies, exhibiting fluctuations across seasons. Consequently, present study prioritizes understanding the adaptation, prevalence, attributes, fluctuations, and spatial dispersion of MPs in both sediment and surface water environments. Furthermore, the study aims to identify existing gaps in the current understanding and underscore opportunities for future investigation. From the present study, it has been reported that, the concentration of MPs in the range of 0.2-45.2 items/L at the Xisha Islands in the south China sea, whereas in India it was found in the range of 96 items/L in water samples and 259 items/kg in sediment samples. This would certainly assist the urban planners in achieving sustainable development goals to mitigate the increasing amount of emergent pollutant load.

PT-seq: A method for metagenomic analysis of phosphorothioate epigenetics in complex microbial communities.

Among dozens of known epigenetic marks, naturally occurring phosphorothioate (PT) DNA modifications are unique in replacing a non-bridging phosphate oxygen with redox-active sulfur and function in prokaryotic restriction-modification and transcriptional regulation. Interest in PTs has grown due to the widespread distribution of the dnd, ssp, and brx genes among bacteria and archaea, as well as the discovery of PTs in 5-10% of gut microbes. Efforts to map PTs in complex microbiomes using existing next-generation and direct sequencing technologies have failed due to poor sensitivity. Here we developed PT-seq as a high-sensitivity method to quantitatively map PTs across genomes and metagenomically identify PT-containing microbes in complex genomic mixtures. Like other methods for mapping PTs in individual genomes, PT-seq exploits targeted DNA strand cleavage at PTs by iodine, followed by sequencing library construction using ligation or template switching approaches. However, PT-specific sequencing reads are dramatically increased by adding steps to heat denature the DNA, block pre-existing 3'-ends, fragment DNA after T-tailing, and enrich iodine-induced breaks using biotin-labeling and streptavidin beads capture. Iterative optimization of the sensitivity and specificity of PT-seq is demonstrated with individual bacteria and human fecal DNA.

Prebiotic chemical reactivity in solution with quantum accuracy and microsecond sampling using neural network potentials

While RNA appears as a good candidate for the first autocatalytic systems preceding the emergence of modern life, the synthesis of RNA oligonucleotides without enzymes remains challenging. Because the uncatalyzed reaction is extremely slow, experimental studies bring limited and indirect information on the reaction mechanism, the nature of which remains debated. Here, we develop neural network potentials (NNPs) to study the phosphoester bond formation in water. While NNPs are becoming routinely applied to nonreactive systems or simple reactions, we demonstrate how they can systematically be trained to explore the reaction phase space for complex reactions involving several proton transfers and exchanges of heavy atoms. We then propagate at moderate computational cost hundreds of nanoseconds of a variety of enhanced sampling simulations with quantum accuracy in explicit solvent conditions. The thermodynamically preferred reaction pathway is a concerted, dissociative mechanism, with the transient formation of a metaphosphate transition state and direct participation of water solvent molecules that facilitate the exchange of protons through the nonbridging phosphate oxygens. Associative-dissociative pathways, characterized by a much tighter pentacoordinated phosphate, are higher in free energy. Our simulations also suggest that diprotonated phosphate, whose reactivity is never directly assessed in the experiments, is significantly less reactive than the monoprotonated species, suggesting that it is probably never the reactive species in normal pH conditions. These observations rationalize unexplained experimental results and the temperature dependence of the reaction rate, and they pave the way for the design of more efficient abiotic catalysts and activating groups.

Hydrological dynamics and manganese mineralization in the wake of the Sturtian glaciation

The Cryogenian Sturtian and Marinoan glaciations stand as the most extreme climate events in Earth history. Intriguingly, large-scale Mn carbonates characterize the nonglacial interlude of this period in South China. The formation mechanism of Mn carbonates and the potential correlation underlying this temporal association remain elusive. Here, we present an integrated petrographic and geochemical study of drill core materials intercepting the Mn-bearing Datangpo Formation. Rare earth element patterns of these Mn carbonates exhibit positive Ce anomalies and a lack of Y anomalies, which differ from those of modern seawater but resemble marine Mn-Fe oxides. These features, combined with negative carbonate carbon isotope compositions (δ13Ccarb as light as −9.9 ‰ VPDB), indicate the presence of oxide precursors and the incorporation of light carbon during Mn-carbonate precipitation. Phosphate oxygen isotope ratios (δ18Op) of HCl-extractable apatite reveal a ∼4 ‰ difference in the average δ18Op between Mn-rich and Mn-poor rocks. We propose that the more positive δ18Op of Mn-rich samples may result from the dominance of phosphate released by reductive dissolution of metal oxides or a heavier oxygen isotope signal of surrounding waters with which isotopic equilibrium has been reached. We further illustrate how marine invasions into coastal anoxic basins could have triggered the formation of Mn oxides and highlight the role of glaciation–deglaciation in the development of giant Mn deposits.

Simulations predict preferred Mg2+ coordination in a nonenzymatic primer-extension reaction center

The mechanism by which genetic information was copied prior to the evolution of ribozymes is of great interest because of its importance to the origin of life. The most effective known process for the nonenzymatic copying of an RNA template is primer extension by a two-step pathway in which 2-aminoimidazole-activated nucleotides first react with each other to form an imidazolium-bridged intermediate that subsequently reacts with the primer. Reaction kinetics, structure-activity relationships, and X-ray crystallography have provided insight into the overall reaction mechanism, but many puzzles remain. In particular, high concentrations of Mg2+ are required for efficient primer extension, but the mechanism by which Mg2+ accelerates primer extension remains unknown. By analogy with the mechanism of DNA and RNA polymerases, a role for Mg2+ in facilitating the deprotonation of the primer 3′-hydroxyl is often assumed, but no catalytic metal ion is seen in crystal structures of the primer-extension complex. To explore the potential effects of Mg2+ binding in the reaction center, we performed atomistic molecular dynamics simulations of a series of modeled complexes in which a Mg2+ ion was placed in the reaction center with inner-sphere coordination with different sets of functional groups. Our simulations suggest that coordination of a Mg2+ ion with both O3′ of the terminal primer nucleotide and the pro-Sp nonbridging oxygen of the reactive phosphate of an imidazolium-bridged dinucleotide would help to pre-organize the structure of the primer/template substrate complex to favor the primer-extension reaction. Our results suggest that the catalytic metal ion may play an important role in overcoming electrostatic repulsion between a deprotonated O3′ and the reactive phosphate of the bridged dinucleotide and lead to testable predictions of the mode of Mg2+ binding that is most relevant to catalysis of primer extension.

Theoretical Study on The Effect of Metal Ions on The Structural Properties of Base

Metal ions play an important role in living organisms, for example Mg2+ is a cofactor for many biological enzymes (including DNA and RNA synthesis), Ca2+ is an important component of bone composition, and metal ions such as Fe, Co, Zn, Ni and Cu also play an important role in the normal functioning of living organisms. One of the main targets of metal ions in living organisms is deoxyribonucleic acid (DNA), which is an important carrier of information stored and transmitted by organisms. The direct interaction between DNA base pairs and metal ions have a significant impact on the structure and function of DNA base pairs, which is demonstrated as following: the binding of metals to bases usually breaks the hydrogen bonds of the base pairs. The N7 atom of a purine residue or the N3 atom of a pyrimidine residue, as well as the outer ring O atom and the phosphate oxygen atom, are the preferred sites for metal binding. The binding of metals to DNA and RNA also indirectly affects the conformation of the sugar ring. REDOX active metal ions have the ability to bind to DNA and can mediate oxidative DNA damage by reacting with endogenous oxidants. According to studies of antioxidants in the field of metal-mediated oxidative DNA damage, metal ion coordination also plays a key role in the mechanism of some antioxidants. Also, metal-DNA interactions are the basis for many anti-cancer drugs, anti-viral drugs and anti-bacterial agents. Metal-mediated oxidative DNA damage is associated with a variety of diseases and conditions, and understanding the binding interactions and subsequent reactivity can facilitate the management or prevention of oxidative damage. It can be seen that the study of the effect of metal ions on the structural properties of DNA bases has far-reaching implications, providing a theoretical basis for the development of novel anticancer drugs, DNA-based metal nanodevice technologies and the fabrication of spectroscopic and reactive probes.

Molecular Origin of Distinct Hydration Dynamics in Double Helical DNA and RNA Sequences.

Water molecules are essential to determine the structure of nucleic acids and mediate their interactions with other biomolecules. Here, we characterize the hydration dynamics of analogous DNA and RNA double helices with unprecedented resolution and elucidate the molecular origin of their differences: first, the localization of the slowest hydration water molecules─in the minor groove in DNA, next to phosphates in RNA─and second, the markedly distinct hydration dynamics of the two phosphate oxygen atoms OR and OS in RNA. Using our Extended Jump Model for water reorientation, we assess the relative importance of previously proposed factors, including the local topography, water bridges, and the presence of ions. We show that the slow hydration dynamics at RNA OR sites is not due to bridging water molecules but is caused by both the larger excluded volume and the stronger initial H-bond next to OR, due to the different phosphate orientations in A-form double helical RNA.

Catalytic Metal Ion-Substrate Coordination during Nonenzymatic RNA Primer Extension.

Nonenzymatic template-directed RNA copying requires catalysis by divalent metal ions. The primer extension reaction involves the attack of the primer 3'-hydroxyl on the adjacent phosphate of a 5'-5'-imidazolium-bridged dinucleotide substrate. However, the nature of the interaction of the catalytic metal ion with the reaction center remains unclear. To explore the coordination of the catalytic metal ion with the imidazolium-bridged dinucleotide substrate, we examined catalysis by oxophilic and thiophilic metal ions with both diastereomers of phosphorothioate-modified substrates. We show that Mg2+ and Cd2+ exhibit opposite preferences for the two phosphorothioate substrate diastereomers, indicating a stereospecific interaction of the divalent cation with one of the nonbridging phosphorus substituents. High-resolution X-ray crystal structures of the products of primer extension with phosphorothioate substrates reveal the absolute stereochemistry of this interaction and indicate that catalysis by Mg2+ involves inner-sphere coordination with the nonbridging phosphate oxygen in the pro-SP position, while thiophilic cadmium ions interact with sulfur in the same position, as in one of the two phosphorothioate substrates. These results collectively suggest that during nonenzymatic RNA primer extension with a 5'-5'-imidazolium-bridged dinucleotide substrate the interaction of the catalytic Mg2+ ion with the pro-SP oxygen of the reactive phosphate plays a crucial role in the metal-catalyzed SN2(P) reaction.

Evaluation of Phosphorus Enrichment in Groundwater by Legacy Phosphorus in Orchard Soils with High Phosphorus Adsorption Capacity Using Phosphate Oxygen Isotope Analysis.

Long-term phosphorus (P) fertilization results in P accumulation in agricultural soil and increases the risk of P leaching into water bodies. However, evaluating P leaching into groundwater is challenging, especially in clay soil with a high P sorption capacity. This study examined whether the combination of PO4 oxygen isotope (δ18OPO4) analysis and the P saturation ratio (PSR) was useful to identify P enrichment mechanisms in groundwater. We investigated the groundwater and possible P sources in Kubi, western Japan, with intensive citrus cultivation. Shallow groundwater had oxic conditions with high PO4 concentrations, and orchard soil P accumulation was high compared with forest soil. Although the soil had a high P sorption capacity, the PSR was above the threshold, indicating a high risk of P leaching from the surface orchard soil. The shallow groundwater δ18OPO4 values were higher than the expected isotopic equilibrium with pyrophosphatase. The high PSR and δ18OPO4 orchard soil values indicated that P leaching from orchard soil was the major P enrichment mechanism. The Bayesian mixing model estimated that 76.6% of the P supplied from the orchard soil was recycled by microorganisms. This demonstrates the utility of δ18OPO4 and the PSR to evaluate the P source and biological recycling in groundwater.

Oxygen Isotope Analysis of Nanomole Phosphate Using PO3- Fragment in ESI-Orbitrap-MS.

The oxygen isotope composition of phosphate is a useful tool for studying biogeochemical phosphorus cycling. However, the current Ag3PO4 method is not only tedious in PO43- extraction and purification but also requires a large-sized sample at the micromole level, thereby limiting its application. Here, we present an approach to measuring the oxygen isotope composition, δ18O, of dissolved phosphate at the nanomole level using electrospray ionization Orbitrap mass spectrometry (ESI-Orbitrap-MS). We compared the reproducibility of δ18O measurements using the H2PO4- ions (m/z = 97 and 99 for H2P16O4- and H2P18O16O3-, respectively) and using the PO3- fragment ions (m/z = 79 and 81 for P16O3- and P18O16O2-, respectively) generated by source fragmentation and by higher-energy collisional dissociation, respectively. The results demonstrate that phosphate δ18O can be more reliably measured by the PO3- ions than by the H2PO4- ions. PO3- generated by source fragmentation at 40 V achieved the highest reproducibility for δ18O based on precision tests. Furthermore, the mass spectrum for a 50:50 μM mixed solution of phosphate and sulfate revealed that PO3- ions resulting from source fragmentation at 40 V are the predominant species in the Orbitrap analyzer. Notably, P16O3- ions (m/z: 79) are not interfered with by 32S16O3- (m/z: 80) ions. This is in contrast to the case for 1H2P16O4- ions, which share the same m/z value with 1H32S16O4- ions and exhibit much lower signal intensity than HSO4- ions. Using the PO3- fragment method and six phosphate standards with a wide range of δ18O values, we obtained a calibration line with a slope of 0.94 (R2 = 0.98). The overall uncertainty for ESI-Orbitrap-MS phosphate δ18O measurement was 0.8‰ (n = 30; 1 SD). With much room for improvement, the PO3- fragment method presents a better approach to measuring the phosphate oxygen isotope composition, applicable to nanomole sample sizes in a liquid phase.

DNA tetrahedron as nanoparticulated delivery system in combating diseases

Many diseases suffer from drug resistance and nucleic acid cargo delivery. To optimize pharmaceutics and to enhance their efficiency of cellular uptake, DNA nanomaterial tetrahedrons, owing to their precise control in size, shape, excellent biocompatibility and cellular permeability, reduced cytotoxicity, good stability, ease synthesis and multiple sites for targeting design, have attracted attention for targeting cargos delivery. Their nanostructural binding efficiency with many cargos depends on their electrostatic attractions among free electrons of phosphate oxygen, sugar and base nitrogen. Self-assembled DNA tetrahedrons (DTs) alone also can regulate cellular processes to some extent, especially, on migration, differentiation, proliferation and autophagy, and their modifications with the attachment of aptamers, peptides, nucleic acids, antibodies, different low-molecular-weight drugs and other components, make them a novel targeted delivery system as effective nanomedicine. This review demonstrates the current progress of DTs towards their synthesis, characterization, biomedical applications, biodistribution, elimination and toxicity as possible nanoparticulated delivery system.&#x0D; Keywords: Diseases; Drug resistance; DNA tetrahedron; nanoparticulated delivery system; Nanomedicine

Numerical Simulation of the Marine Environmental Capacity of Jinpu Bay

Based on the study of the marine environmental capacity, a water quality model and a response field-based linear programming method are adopted here. Water quality control objectives are taken as the constraint conditions, according to the requirements of Jinpu Bay’s functional zoning. The pollutant response coefficient and water quality background value are combined with the values of the water concentration quality control points set in each functional area and the target value of the functional area wherein they are located. The maximum allowable emission intensity of inorganic nitrogen, phosphate and chemical oxygen demand (COD) can be calculated using the linear programming method of the maximum allowable emission of pollutants at estuaries or sewage outfall points on Jinpu Bay. The research results reveal the diffusion of marine pollutants and the marine environmental capacity of Jinpu Bay. Some rivers need to reduce the discharge intensity and some other outlets still have a certain residual capacity. Based on this, the environmental capacity of Jinpu Bay was evaluated, and a technical reference is provided for the economic development of the region and the formulation of pollutant emission control policies.

Erythrocyte metabolism.

Our aim is to present an updated overview of the erythrocyte metabolism highlighting its richness and complexity. We have manually collected and connected the available biochemical pathways and integrated them into a functional metabolic map. The focus of this map is on the main biochemical pathways consisting of glycolysis, the pentose phosphate pathway, redox metabolism, oxygen metabolism, purine/nucleoside metabolism, and membrane transport. Other recently emerging pathways are also curated, like the methionine salvage pathway, the glyoxalase system, carnitine metabolism, and the lands cycle, as well as remnants of the carboxylic acid metabolism. An additional goal of this review is to present the dynamics of erythrocyte metabolism, providing key numbers used to perform basic quantitative analyses. By synthesizing experimental and computational data, we conclude that glycolysis, pentose phosphate pathway, and redox metabolism are the foundations of erythrocyte metabolism. Additionally, the erythrocyte can sense oxygen levels and oxidative stress adjusting its mechanics, metabolism, and function. In conclusion, fine-tuning of erythrocyte metabolism controls one of the most important biological processes, that is, oxygen loading, transport, and delivery.

The impact of mariculture biofilters on the distribution of benthic nutrient fluxes, organic matters and bacterial community in a mariculture wastewater treatment system

Constructed-wetlands, biofilms, and sedimentation are among biological filters used in mariculture wastewater treatments, however, their impacts on the distribution of benthic microbial community and inorganic-nutrient fluxes have not been fully explored. This study applied 16 S rRNA high-throughput sequencing technology to investigate the microbial community distribution and their impacts on nutrient fluxes in mariculture biofilters system. Results showed that bacterial community compositions were significantly different in the constructed-wetland and biofilm treatments (p < 0.05) relative to sedimentation. The composition of the 16 S rRNA genes among the treatments were enriched with Proteobacteria (73%), Bacteroidetes (69%), Firmicutes (62%), and Flavobacteria (61%) in Biofilm compared to Proteobacteria (53%), Bacteroidetes (39%), Firmicutes (32%), and Flavobacteria (21%) in constructed wetlands. NMDS analysis showed that bacterial composition in constructed-wetland and biofilms clustered separately compared to sedimentation treatment. Functional-Annotation-of-Prokaryotic-Taxa analysis indicated that the proportions of sediment-microbial-functional groups (aerobic-chemoheterotrophy, chemoheterotrophy, and nitrate-ammonification) were 47% in the constructed-wetland, 32% in biofilm and 13% in sedimentation system. Benthic-nutrient fluxes for phosphate, ammonium, nitrite, nitrate and sediment oxygen consumption differed markedly among the treatments (p < 0.05). Canonical correspondence analysis indicated constructed-wetland had the strongest association between biogeochemical contents and the bacterial community relative to other treatments. This study suggests that the mariculture wastewater biofilters promoted microbial community distributions, sediment bacterial functional-groups including chemoheterotrophy, aerobic-chemoheterotrophy, denitrification, and nitrification and interactions with nutrient fluxes which was more pronounced in the constructed-wetland system.

A pentametallic Co5L4 architecture constructed from bis-substituted phosphate-based ligands

A Co5L4 supramolecular square was synthesised via self-assembly from a bis-substituted phosphate ligand, interconnected by the phosphate oxygen atoms.