Complex Substrates Research Articles

In Situ SERS Monitoring of Schiff Base Reactions via Nanoparticles on a Mirror Platform

Schiff base reactions are widely used in pharmacy, catalysis, and volatile aldehyde detection. However, common biomarker sensing methods struggle to monitor this reaction process precisely due to their sensitivity, their time-consuming nature, and complex substrates. Here, we introduce the Nanoparticle-on-Mirror structure for in situ monitoring this reaction process through the application of a Au nanoparticle-p-Aminothiophenol-Au thin-film platform by surface-enhanced Raman scattering (SERS). Owing to the exposure of -NH2 groups and the local ultra-strong electromagnetic field in the nanocavity, the Schiff base reactions process can be rapidly monitored within two minutes. Meanwhile, the monitoring platform can detect benzaldehyde molecules as low as 10−6 M, showing excellent SERS performance. Notably, the Au-nanoparticle-p-Aminothiophenol-Au thin-film platform exhibited anti-interference and specificity, being able to identify BA in the presence of interference. The use of the Au-nanoparticle-p-Aminothiophenol-Au thin-film platform provides a sensing method for Schiff base reactions with accuracy and simplicity of operation, achieving a balanced approach for low-cost and high-performance real-time monitoring, which is expected to be applied in various catalytic reaction process monitoring and catalyst design processes.

Coal-straw co-digestion-induced biogenic methane production: perspectives on microbial communities and associated metabolic pathways

This study assessed the impacts of wheat straw as a cosubstrate on coal biocoverion into methane and the associated mechanism within methane metabolic pathways. Co-digestion of coal with varying wheat straw concentrations resulted in a remarkable (1246.05%) increase in methane yield compared to that of the control (CK). Moreover, microbial analysis revealed a uniform distribution of Methanosarcinaceae (51.14%) and Methanobacteriaceae (39.90%) in the co-digestion of coal and wheat straw (CWS1) at a ratio of 3:1 (w/w) compared to other treatments such as coal and wheat straw (CWS2) at a ratio of 3:0.5. In addition, Hungatieclostridiaceae and Rhodobacteriaceae were abundant in both co-digesters, whereas the bacterial communities in the CK group were significantly different and more abundant than those in the Peptostreptococcaceae and Enterobacteriaceae groups. The key enzymes related to methanogenic metabolic pathways, including EC: 1.2.99.5 and EC: 2.1.1.86 (facilitating the conversion of CO2 into methane), and EC:1.12.98.1 exhibited significant abundance within CWS1. Aromatic compounds such as 4-(2-chloroanilino)-4-oxobutanoic acid and phthalic acid were substantially more abundant in CWS1 and CWS2 than in CK, indicating the increased bioavailability of coal to microbial activities. This novel approach demonstrates that wheat straw co-digestion with coal during anaerobic digestion modulates microbial communities and their metabolic pathways to enhance methane production from complex substrates such as coal.

Effects of DOM and cations on the diffusion migration of PPCPs through ion exchange membranes

The transportation of pharmaceuticals and personal care products (PPCPs) in ion-exchange membranes was worrying, especially in complex substrates. Dissolved organic matter (DOM), the complexation of PPCPs and the membrane pollution formed by DOM were often confused in the existing studies. This paper investigated the diffusive migration patterns of three kinds of (PPCPs) through ion exchange membranes (IEMs) in complex substrates. Triclosan (TCS) exhibited the most probability of migration. Without considering the interference of environmental factors, more than 90 % of TCS was adsorbed by IEMs. The migration of sulfadiazine sodium (SD) and carbamazepine (CBZ) was less than 5 %. The DOM and cations altered the interaction of PPCPs and IEMs. DOM fouling on IEMs converted the direct strong binding of TCS to IEMs to indirect weak binding, and increased the transmembrane migration of TCS consequently. The presence of cations (Ca2+ and Mg2+) increased the inorganic binding of TCS to IEMs, and also promoted the transmembrane migration of TCS. However, coexisting of Mg2+ and humic acid (HA) decreased TCS migration through anion exchange membrane (AM), but increased TCS migration through cation exchange membrane (CM) due to the increasing of solution potential. The research provided a theoretical basis for exploring the safety of product solutions in IEMs systems.

Potential application of room temperature synthesized MIL-100(Fe) in enhancing methane production in microbial electrolysis Cells-Anaerobic digestion treating Protein-Rich wastewater

Microbial electrolysis cell-anaerobic digestion (MEC-AD) is an emerging technology for methane production. However, low substrate degradation efficiency remains a challenge when processing protein substrates. This study developed a MIL-100(Fe) carbon cloth anode to enhance methane production and substrate degradation in MEC-AD. The effects of MIL-100(Fe) prepared under hydrothermal (H-MIL-100(Fe)) and room temperature conditions (R-MIL-100(Fe)) were compared. Results indicated that H-MIL-100(Fe) and R-MIL-100(Fe) increased cumulative methane production by 16.01% and 14.99%, respectively compared to normal cloth, each influencing methane production through distinct mechanisms. Electrochemical characterization showed that H-MIL-100(Fe) enhanced the electrochemical performance more significantly due to the enrichment of Geotalea, with the oxidation current improved by 7.39-fold (R-MIL-100(Fe) increased it by only 2.95-fold) to promote growth of Methanobacterium. Metagenomic analysis revealed that R-MIL-100(Fe) tended to metabolize amino acids into methane rather than support cellular life activities, indicating its practicality under limited substrate concentration. In summary, R-MIL-100(Fe) shows greater potential for application due to its mild synthesis conditions and advantages in treating complex substrates.

Cs2CO3-Catalyzed Rauhut-Currier-Type Reaction for the Synthesis of 2,3-Dihydrobenzo[b]oxepin Derivatives.

The synthesis of fused benzoxepines relies on the use of complex substrates and methodologies. Herein, we report our experimental and theoretical findings about an unprecedented Rauhut-Currier-type reaction catalyzed by Cs2CO3 to access these important compounds. The developed methodology avoids the use of phosphine- or amine-based catalysts and additives. The reaction can be performed under microwave irradiation and proceeds with complete chemoselectivity.

Late-stage Functionalization using a Popular Titrating Agent: Aryl-Chlorides and -Fluorides Activation by the Diphenylacetic Acid Dianion.

Aryl-chlorides and -fluorides are common building blocks, but their use in synthesis is limited by the high stability of their Ar-X bonds. The generation of aryl radicals via activation of strong Ar-X bonds is possible through the irradiation of tailor-made organic anions, which become reductants stronger than lithium metal. We report that the combination of visible light with the cheap diphenylacetic acid dianion is an even better tool, showing excellent activity across a variety of complex substrates and providing opportunities for late-stage drug modification. Ar-X bonds are chemoselectively activated in the presence of more easily reducible functions, such as Alk-Cl ones and carbonyl groups. These results pave the way to original synthetic strategies that would be otherwise considered impossible.

Is enzymatic stoichiometry a reliable indicator of microbial limitations in carbon, nitrogen, or phosphorus?

The enzymatic stoichiometry approach is based on the assumption that the metabolic and stoichiometric requirements of soil microorganisms are reflected in the production of enzymes targeting specific nutrient resources, making enzyme activities a useful tool for assessing microbial nutrient limitations. In this approach, β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG) (occasionally combined with leucine aminopeptidase, LAP), and acid/alkaline phosphatase (AP) are used as proxies for the broader suite of enzymes responsible for catalyzing complex substrates containing carbon (C), nitrogen (N), and phosphorus (P), respectively, because these enzymes catalyze the terminal reactions that release products containing C, N, and P. The fundamental premise of the approach can thus be reformulated as follows: BG:NAG and BG:AP ratios reflect the relative limitations of C versus N and C versus P, respectively, with higher ratios indicating stronger C limitation. Previous meta-analyses have suggested that the enzymatic stoichiometry approach is unreliable, as N and P fertilization often leads to reduction in BG:NAG and BG:AP, respectively, contradicting the predictions of the approach. However, some researchers question the validity of assessing enzymatic stoichiometry after the artificial addition of nutrients via fertilizers. For providing more convincing evidence, this study conducted a meta-analysis to assess the impact of incorporating various C sources, largely representative of those found in natural ecosystems—glucose, cellulose, and plant residues—on the BG:NAG or BG:AP ratios. The results demonstrated that a considerable number of data points exhibited elevated values (i.e., C addition accelerated C limitations), undoubtedly contradicting the fundamental premise of the approach. These findings highlight the unreliability of enzymatic stoichiometry as an indicator of microbial nutrient limitation.

Evaluation of a mixture of livestock wastewater and food waste as a substrate in a continuous-flow microbial electrolysis cell

While the efficiency of microbial electrolysis cell (MEC) systems has improved remarkably, their application in continuous reactors and wastewater treatment remains poorly understood. This study evaluated the performance of a continuous-flow MEC using livestock wastewater and food waste as substrates. The MEC system achieved a hydrogen production rate of 5.2 L/L/day using acetate as a substrate, and a rate of 2.9–4.6 L/L/day when real wastewater mixtures were used. In terms of chemical oxygen demand (COD) removal, the system demonstrated high efficiency, with values ranging from 42.3 % to 62.2 % depending on the wastewater composition. Volatile fatty acid (VFA) removal reached up to 72.8 %. The current density averaged 9.9 A/m2 with acetate and decreased to 7.0 and 6.1 A/m2 in phases using wastewater, reflecting the adaptation of the microbial community to the more complex substrates. The microbial community was dominated by Firmicutes, Bacteroidetes, Proteobacteria, and Synergistetes, with Proteobacteria showing a particularly high abundance near the anion exchange membrane (AEM) on the anode. The MEC process demonstrates substantial promise as a sustainable technology for both biohydrogen production and wastewater treatment. With further optimization and scaling, MECs could play a crucial role in the circular economy by converting waste into clean energy while simultaneously treating wastewater, offering a pathway toward more sustainable industrial and environmental practices.

Unraveling the synergistic interplay of sulfur and wheat straw in heterotrophic-autotrophic denitrification for sustainable groundwater nitrate remediation

Nitrate pollution in groundwater is a global environmental issue that poses significant threats to human health and ecological security. This study focuses on elucidating the mechanisms of heterotrophic-autotrophic cooperative denitrification (HAD) by employing wheat straw and elemental sulfur as electron donors in varying proportions. The research initially underscores that heterotrophic denitrification (HD) accelerates the denitrification process due to its high-energy metabolism. However, as readily degradable organic matter diminished, reliance on more complex substrates such as lignocellulose posed a challenge to HD. This marks a pivotal transition towards autotrophic denitrification (AD), which, despite a slower initial rate, exhibits a more sustained denitrification performance. A low proportion of heterotrophic denitrification layer (e.g., 3:1) at the bottom facilitating efficient and sustainable denitrification. HD is capable of simultaneous removal of nitrates and nitrites, whereas AD demonstrates a higher affinity for nitrates, with nitrite accumulation reaching 100% at high influent nitrate concentrations (100 mg/L). HD not only provides the necessary alkaline environment for AD but also reduces sulfate production, whereas AD utilizes the residual organic carbon and ammonia produced by HD. The heterotrophic layer is characterized by a diverse community, whereas the autotrophic layer is predominantly composed of Thiobacillus. By delineating the interactive mechanisms and characteristics of HAD, this study highlights the importance of balancing heterotrophic and autotrophic activities for the effective remediation of groundwater nitrates.

Signal switching electrochemical and fluorescence dual-mode sensing platform for carbendazim determination based on “two-in-one” magneto-fluorescent Cdots

An innovative method for carbendazim (CBZ) detection was developed, consisting of an electrochemical-fluorescence dual-mode biosensor based on magneto-fluorescent composite M-CDs. M-CDs, as the fluorescent probe of this sensor, could combine the electrical signal-ferrocene to achieve the “signal switching” by specifically recognizing CBZ through aptamers, of which magnetic property was used to quickly separate from complex substrates without interference. The dual-mode sensor based on M-CDs demonstrated excellent linear responses in both electrochemical and fluorescence assays. It achieved detection ranges of 10 fg/mL − 300 ng/mL and 60 fg/mL – 100 ng/mL with detection limits (LODs) of 1.4 fg/mL and 2.3 fg/mL. The sensor exhibited exceptional detection performance, stability and anti-interference. In addition, the results of the sensor in actual samples were consistent with those of enzyme-linked immunosorbent assay (ELISA), which further demonstrated that the sensor could accurately trace detecting CBZ in real samples and had a certain application prospect.

Skeletal Editing through Single-Atom Insertion and Transmutation: An Insight into a New Era of Synthetic Organic Chemistry

AbstractConsidering the importance of heterocycles, significantly represented in medicinal chemistry and drug development, the single-atom insertion technique and transmutation strategy provide productive approaches towards complicated molecular structures through heterocycle diversification. It shows a potentially powerful approach for modifying complex substrates concisely and chemospecifically. Although skeletal editing applies to cyclic and acyclic compounds, this review focuses on the diversification of carbo- and heterocyclic compounds for synthesizing various medicinally important molecules via the single-atom insertion technique. The classification system is based on recent and critical historical methods of single-atom insertion as applied to the transmutation of aromatic rings.1 Introduction2 Skeletal Editing through Carbon-Atom Insertion2.1 Skeletal Editing of Indoles and Pyrroles Derivatives: Carbon-Atom Insertion into a C=C Bond2.2 Skeletal Editing of Pyrazole and Indazole Derivatives: Carbon-Atom Insertion into an N–N Bond2.3 Skeletal Editing of Pyrazole and Indazole Derivatives: Insertion of CF3 Group into Heteroarenes2.4 Skeletal Editing of Imidazole Derivatives: Carbon-Atom Insertion into C–N Bond2.5 Skeletal Editing through Atom-to-Atom Transmutation3 Skeletal Editing through N-Atom Insertion3.1 Nitrogen-Atom Insertion into Carbocycles3.2 Nitrogen-Atom Insertion into Heterocycles3.3 Carbon to Nitrogen Transmutation3.3 Molecular Editing through Isotopic Transmutation4 Conclusion

Late-Stage Halogenation of Complex Substrates with Readily Available Halogenating Reagents.

ConspectusLate-stage halogenation, targeting specific positions in complex substrates, has gained significant attention due to its potential for diversifying and functionalizing complex molecules such as natural products and pharmaceutical intermediates. Utilizing readily available halogenating reagents, such as hydrogen halides (HX), N-halosuccinimides (NXS), and dichloroethane (DCE) reagents for late-stage halogenation shows great promise for expanding the toolbox of synthetic chemists. However, the reactivity of haleniums (X+, X = Cl, Br, I) can be significantly hindered by the presence of various functional groups such as hydroxyl, amine, amide, or carboxylic acid groups. The developed methods of late-stage halogenation often rely on specialized activating reagents and conditions. Recently, our group (among others) has put great efforts into addressing these challenges and unlocking the potential of these readily available HX, NXS, and DCE reagents in complex molecule halogenation. Developing new methodologies, catalyst systems, and reaction conditions further enhanced their utility, enabling the efficient and selective halogenation of intricate substrates.With the long-term goal of achieving selective halogenation of complex molecules, we summarize herein three complementary research topics in our group: (1) Efficient oxidative halogenations: Taking inspiration from naturally occurring enzyme-catalyzed oxidative halogenation reactions, we focused on developing cost-effective oxidative halogenation reactions. We found the combination of dimethyl sulfoxide (DMSO) and HX (X = Cl, Br, I) efficient for the oxidative halogenation of aromatic compounds and alkenes. Additionally, we developed electrochemical oxidative halogenation using DCE as a practical chlorinating reagent for chlorination of (hetero)arenes. (2) Halenium reagent activation: Direct electrophilic halogenation using halenium reagents is a reliable method for obtaining organohalides. However, compared to highly reactive reagents, the common and readily available NXS and dihalodimethylhydantoin (DXDMH) demonstrate relatively lower reactivity. Therefore, we focused on developing oxygen-centered Lewis base catalysts such as DMSO, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and nitromethane to activate NXS or DXDMH, enabling selective halogenation of bioactive substrates. (3) Halogenation of inert substrates: Some substrates, such as electron-poor arenes and pyridines, are inert toward electrophilic functionalization reactions. We devised several strategies to enhance the reactivity of these molecules. These strategies, characterized by mild reaction conditions, the ready availability and stability of catalysts and reagents, and excellent tolerance for various functional groups, have emerged as versatile protocols for the late-stage aromatic halogenation of drugs, natural products, and peptides. By harnessing the versatility and selectivity of these catalysts and methodologies, synthetic chemists can unlock new possibilities in the synthesis of halogenated compounds, paving the way for the development of novel functional materials and biologically active molecules.

A dendrimer-based platform integrating surface-enhanced Raman scattering and class-incremental learning for rapidly detecting four pathogenic bacteria

Rapid monitoring of pathogens is crucial for preventing foodborne diseases, thus making it an urgent need to develop efficient, fast, and simple methods for on-site detection of multiple pathogens. With advances in SERS-based label-free biosensors and machine learning, progress is evident, yet challenges such as complex substrates and limited model interpretability persist. In this work, we reported a novel dendrimer-based platform that integrated surface-enhanced Raman scattering (SERS) with class-incremental learning (CIL) for quick and simultaneous detection of four pathogenic bacteria, namely Escherichia coli, Salmonella Paratyphi B, Pseudomonas aeruginosa, and Staphylococcus aureus. First, the poly(amidoamine) (PAMAM)-based gold nanoassemblies on silicon wafer (PGNAs/Si) was designed as a highly active SERS substrate with an easy fabrication process. Compared with naked gold nanoparticles, both sensitivity and repeatability were improved by introducing a controllable dendritic nanostructure with ultra-small internal nanogaps. The detection limits of four pathogens in water, food, and dietary supplement matrices were all on the order of 10 CFU/mL. Subsequently, to analyze the complex SERS spectra and distinguish samples with different pathogens, CIL models were established using the light gradient boosting machine (LightGBM) algorithm. Notably, the discriminative models demonstrated excellent classification performance with an accuracy of over 93.44 %. Further, the SHapley Additive exPlanations (SHAP) method was utilized to identify the key SERS features in accurately discriminating different pathogens. Together, these results demonstrate that the dendrimer-based platform, by integrating SERS with CIL, can rapidly detect four pathogenic bacteria, underscoring its potential for food safety testing or quality monitoring in medical supplies manufacturing.

Electrochemical sensing for simultaneous determination of dopamine and acetaminophen based on ZIF-8@ZIF-67 derived Co/Mo2C embedded in N-doped carbon hollow nanocages

The exploration of an economical and efficient noble metal-free heterogeneous catalyst is of great significance for the construction of an electrochemical method for the simultaneous detection of Dopamine (DA) and acetaminophen (AC). In this paper, we employed a facile strategy to obtain Co/Mo2C nanoparticles embedded in nitrogen-doped carbon hollow nanocages (Co/Mo2C@N-C HNCs) heterogeneous structure by pyrolyzing ZIF-8@ZIF-67 precursor. The unique hollow structure ensures a fast electron transport channel, N doping regulates the local electronic structure of the catalyst, and the synergistic effect with Mo2C and Co nanoparticles provides more electrocatalytic active sites. The Co/Mo2C@N-C HNCs electrode separates the overlapping voltammetry peaks of DA and AC into two distinct voltammetry peaks (△E=200 mV), thereby selectively determining DA in the presence of AC and vice versa. The transfer coefficient (α) and electron transfer number (n) of DA and AC electrocatalytic oxidation were also studied. Using Co/Mo2C@N-C HNCs as electrode, an electrochemical sensor platform for the simultaneous detection of acetaminophen (AC) and dopamine (DA) was first constructed with linear range of 1–185 μM, and 1–100 μM and low detection limit of 0.35 μM and 0.46 μM for AC and DA, respectively. Satisfactory results have been obtained in the determination of human serum and acetaminophen tablets samples. DFT calculation reveals the molecular mechanisms for DA and AC interacting with the Co/Mo2C@N-C HNCs catalysts. This strategy provides a new idea for the selective determination of several analytes in complex substrates.

How substrate surface area and surface curvature determine kinetics and titanate formation during non-hydrothermal alkali treatment of titanium microspheres

Titanium surface nanostructuring using alkali treatment gains significant attention in a wide range of fields, such as biomaterials, (photo)catalysis, (metal/ion) sorption, CO2 capture, electrochromism and sodium-ion batteries. Even though the physicochemical properties and application potentials of the surface nanostructures are fairly well understood, there is still debate about their exact formation mechanism, limiting knowledge based structural control through altered synthesis conditions. Moreover, this knowledge is largely focused on hydrothermal synthesis conditions, whereas non-hydrothermal conditions might provide benefits towards industrial application. Also the impact of substrate properties, rather than chemical reaction conditions, on the nanostructure formation is only limitedly reported in literature. This work reveals new fundamental knowledge of non-hydrothermal alkali treatment of titanium, using microspheres by implementing, for the first time, in-situ hydrogen measurement during alkali treatment in combination with the ex-situ determination of the sodium and oxygen content in the recovered alkali treated samples, providing critical information on the role of dissolution apart from the precipitation process. The effect of surface area and surface curvature on the dissolution and precipitation process, and the resulting impact on the physicochemical properties of the obtained titanate layer is studied. This shows the much larger impact on dissolution in contrast to precipitation, knowledge that is lacking in literature, but important when implementing alkali surface nanostructuring on complex (e.g. 3D printed) substrates, and considering the prospective shift from lab-scale to industry. The Ti dissolution step was found to be mainly controlled by the total surface area, while the rate determining step was found to be the titanate precipitation, not influenced by either surface area or particle size.The changes in oxygen content in the samples after transformation of titanate into TiO2 provided a novel method for its quantification. The microspheres were analysed chemically (Raman), structurally (XRD) and morphologically (SEM, MIP), screening the effect of surface area, particle size and reaction time on the growth behaviour of the titanate layer. The porous layer structurally corresponds to Na2Ti2O4(OH)2 for all evaluated conditions, with pores in the range of 10–600 nm. Increasing surface area and particle size results in local and non-uniform titanate growth, while titanate nanowire and strut formation between the microspheres were enhanced by reduced microsphere size and prolonged reaction times.

A Modified Arbuzov-Michalis Reaction for Selective Alkylation of Nucleophiles.

The alkylation of nucleophiles is among the most fundamental and well-developed transformations in chemistry. However, to achieve selective alkylation of complex substrates remains a nontrivial task. We report herein a general and selective alkylation method without using strong acids, bases, or metals. In this method, the readily available phosphinites/phosphites, in combination with ethyl acrylate, function as effective alkylating agents. Various nucleophilic groups, including alcohols, phenols, carboxylic acids, imides, and thiols can be alkylated. This method can be applied in the late-stage alkylation of natural products and pharmaceutical agents, achieving chemo- and site-selective modification of complex substrates. Experimental studies indicate the relative reactivity of a nucleophile depends on its acidity and its steric environment. Mechanistic studies suggest the reaction pathway resembles that of the Arbuzov-Michalis reaction.

A Modified Arbuzov‐Michalis Reaction for Selective Alkylation of Nucleophiles

AbstractThe alkylation of nucleophiles is among the most fundamental and well‐developed transformations in chemistry. However, to achieve selective alkylation of complex substrates remains a nontrivial task. We report herein a general and selective alkylation method without using strong acids, bases, or metals. In this method, the readily available phosphinites/phosphites, in combination with ethyl acrylate, function as effective alkylating agents. Various nucleophilic groups, including alcohols, phenols, carboxylic acids, imides, and thiols can be alkylated. This method can be applied in the late‐stage alkylation of natural products and pharmaceutical agents, achieving chemo‐ and site‐selective modification of complex substrates. Experimental studies indicate the relative reactivity of a nucleophile depends on its acidity and its steric environment. Mechanistic studies suggest the reaction pathway resembles that of the Arbuzov‐Michalis reaction.

Ecosystem engineers enhance the multifunctionality of an urban novel ecosystem: Population persistence and ecosystem resilience since the 1980s

In degraded urban habitats, nature-based solutions aim to enhance ecosystem functioning and service provision. Bivalves are increasingly reintroduced to urban environments to enhance water quality through biofiltration, yet their long-term sustainability remains uncertain. Following the restoration of the disused South Docks in Liverpool in the 1980s, natural colonization of mussels rapidly improved dock-basin water quality and supported diverse taxa, including other filter feeders. While the initial colonization phase has been well documented, there has been limited published research since the mid-1990s, despite ongoing routine water quality monitoring. Here, we assessed the long-term persistence of mussel populations, their associated biodiversity, and physico-chemical parameters of the water in Queens and Albert Docks by comparing historical (1980s to 1990s) and contemporary data from follow-up surveys (2012,2022). Following an initial period of poor water quality (high contamination and turbidity, low oxygen), the natural colonization of mussels from Albert Dock in 1988 extended throughout the South Docks. By the mid-1990s, the environment of the South Docks and its mussel populations had stabilized. The dock walls were dominated by mussels which provided important complex secondary substrate for invertebrates and macroalgae. Surveys conducted in 2012 and 2022 confirmed the continued dominance of mussels and estimates of mussel biofiltration rates confirm that mussels are continuing to contribute to maintaining water quality. A decline in salinity was observed in both docks in 2022, with evidence of recovery. While these ecosystems appear relatively stable, careful management of the hydrological regime is crucial to ensuring the persistence of mussels and resilient ecosystem service provision through biofiltration.

Oxyplasma meridianum gen. nov., sp. nov., an extremely acidophilic organotrophic member of the order Thermoplasmatales.

A mesophilic, hyperacidophilic archaeon, strain M1T, was isolated from a rock sample from Vulcano Island, Italy. Cells of this organism were cocci with an average diameter of 1 µm. Some cells possessed filaments. The strain grew in the range of temperatures between 15 and 52 °C and pH 0.5-4.0 with growth optima at 40 °C and pH 1.0. Strain M1T was aerobic and chemoorganotrophic, growing on complex substrates, such as casamino acids, trypticase, tryptone, yeast and beef extracts. No growth at expenses of oxidation of elemental sulphur or reduced sulphur compounds, pyrite, or ferrous sulphate was observed. The core lipids were glycerol dibiphytanyl glycerol tetraether lipids (membrane spanning) with 0 to 4 cyclopentane moieties and archaeol, with trace amounts of hydroxy archaeol. The dominant quinone was MK-7 : 7. The genome size of M1T was 1.67 Mbp with a G+C content of 39.76 mol%, and both characteristics were well within the common range for Thermoplasmatales. The phylogenetic analysis based on 16S rRNA gene sequence placed the strain M1T within the order Thermoplasmatales with sequence identities of 90.9, 90.3 and 90.5% to the closest SSU rRNA gene sequences from organisms with validly published names, Thermoplasma acidophilum, Thermoplasma volcanium and Thermogymnomonas acidicola, respectively. Based on the results of our genomic, phylogenetic, physiological and chemotaxonomic studies, we propose that strain M1T (=DSM 116605T=JCM 36570T) represents a new genus and species, Oxyplasma meridianum gen. nov., sp. nov., within the order Thermoplasmatales.

Distribution of pelagic and demersal fish assemblages by video prospection in the archipelago of Fernando de Noronha

This study presents an approach that complements previously identified trends in the distribution of acoustic biomass of demersal and pelagic fishes in Fernando de Noronha. Using underwater video as the main method of analysis, patterns of relative fish abundance were evaluated as indicators of biomass, richness, and trophic levels of demersal and pelagic assemblages. Thus, depth stratum, Marine Protected Area (MPA) including the National Marine Park and the Sustainable Fishing Zone, and oceanographic/abiotic factors (e.g., winds, currents, and substrate complexity) were considered. The results confirm that complex substrates and shallow areas (0–20 m) are characterised by greater abundance and species richness. However, it is important to note the limitation of video in detecting fish in deeper areas. Wind exposure also positively influences the abundance and diversity of demersal fish, demonstrating the impact of the "island effect" on species distribution. The research also highlights the relevance of the MPA in Fernando de Noronha for both biodiversity conservation and the sustainability of fishing activities. However, the analysis of trophic levels revealed an increased prevalence of higher trophic levels outside the MPA, mainly due to the abundance of the species Melichthys niger. The presence of complex substrates and lower trophic competition may explain this observation. Therefore, the study provides important insights for the planning of MPAs and the need to include the spatial distribution of higher trophic level species for marine conservation.