Search Results (243)

In 2024, an accident involving two tankers in the Kerch Strait resulted in the release of approximately 2400 tons of fuel oil into the Black Sea, causing significant contamination of seawater and the coastal zone. This study presents the first microbiological and molecular–ecological assessment of prokaryotic community composition and hydrocarbon-oxidizing bacteria (HOB) in coastal seawater and sand near Anapa (Russian Federation) following the spill. The taxonomic composition of nine samples was analyzed using high-throughput sequencing of 16S rRNA genes (V3–V4 regions), identifying Bacteria as the dominant domain (85.3–99.8%). In seawater samples, bacteria of the phyla Pseudomonadota, Cyanobacteriota, and Bacteroidota and archaea of the phyla Thermoplasmatota and Crenarchaeota predominated. Eighteen aerobic bacterial strains, including members of the genera Shewanella, Pseudoalteromonas, Halopseudomonas, Marinomonas, Pseudomonas, Vibrio, Alcanivorax, Ectopseudomonas, Nitratireductor, and Echinicola, were isolated from the zone of fuel oil spill. Several isolates demonstrated heavy oil degradation and biosurfactant production. Screening of collection strains isolated from other habitats revealed that Rhodococcus erythropolis TG65 and Marinobacter lutaoensis Pd1 and Pd2 degraded 92–94% of fuel oil n-alkanes. Elevated dissolved iron concentrations in the seawater indicate the possibility of a metabolic coupling between hydrocarbon oxidation and microbial iron reduction, mediated by indigenous Shewanella and Pseudomonas species. These findings indicate that indigenous HOB may contribute to the natural attenuation of aliphatic hydrocarbons in fuel oil. Full article

Drought stress severely constrains sorghum productivity, and seed priming has emerged as a potential strategy to enhance stress resilience. However, the role of cuticle deposition in seed priming-mediated drought tolerance remains unclear. In this study, the optimal GA priming concentration was determined and its effects on cuticular wax and cutin composition, as well as leaf water loss, were investigated in sorghum seedlings. A preliminary experiment identified 10 mg L⁻¹ GA as the optimal dose, as it produced the greatest height (11.5%) and biomass (79.8%) under drought stress while significantly reducing MDA and O₂⁻ levels, indicating effective alleviation of oxidative damage. Under well-watered conditions, GA priming moderately increased alkanes (45.6%) and primary alcohols (16.3%) while reducing aldehydes (27.3%). However, under drought conditions, GA induced substantially greater increases in alkanes (76.4%), primary alcohols (257.3%), amyrin (451.5%), and other alcohols (56.3%). Regarding cutin monomers, GA further elevated alkanoic acids and cyclopropaneoctanoic acid by 58.2% and 31.4%, respectively, on top of drought-induced accumulation, indicating a synergistic effect between GA and drought signals in promoting cuticular deposition. Additionally, GA redirected the production of cutin with a chain length of C16/C18 towardC22 cutin. GA-primed plants displayed the lowest water loss rates, correlating with enhanced cuticular deposition. Collectively, these findings demonstrate that, in the single genotype tested under controlled-environment conditions, GA priming enhances drought tolerance in sorghum seedlings, acting through the modulation of cuticle composition to reduce leaf water loss while alleviating oxidative damage and improving growth. Full article

Atractylodis Rhizoma is an important traditional Chinese medicinal material derived from two botanical origins, Maocangzhu (MCZ) and Beicangzhu (BCZ), which are difficult to distinguish by conventional morphological identification because of their similar appearance. However, differences in botanical origin may lead to variations in odor, taste, volatile constituents, and non-volatile metabolites, thereby affecting quality evaluation and clinical application. This study aimed to systematically characterize the sensory and chemical differences between MCZ and BCZ and to identify potential markers for their discrimination. A multi-dimensional analytical strategy combining electronic nose, electronic tongue, headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS), and ultra-high-performance liquid chromatography–Orbitrap high-resolution mass spectrometry (UPLC-Orbitrap MS) was established. Electronic nose and electronic tongue were used to digitize odor and taste characteristics, HS-GC-IMS was employed to profile volatile organic compounds, and UPLC-Orbitrap MS was applied to characterize non-volatile metabolites. Principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA), variable importance in projection (VIP) screening, permutation tests, and correlation analysis were further used to evaluate discrimination performance and screen characteristic markers. The electronic nose results showed that MCZ and BCZ exhibited distinct odor profiles, with W5S, W1W, and W1S identified as the main differential sensors, suggesting that nitrogen oxides, terpenoids, inorganic sulfides, and short-chain alkanes contributed to the odor differences between the two origins. Electronic tongue analysis further demonstrated clear taste discrimination, with sourness and richness identified as the key taste indicators. HS-GC-IMS detected 108 volatile organic compounds, and 24 volatile markers with VIP > 1.2 were screened as important contributors to the differentiation of MCZ and BCZ. Among them, propionic acid and 5-methyl-2-furancarboxaldehyde were mainly distributed in MCZ, whereas (E)-caryophyllene was present only or at higher levels in BCZ, indicating its potential as a characteristic volatile marker of BCZ. UPLC-Orbitrap MS detected 78 non-volatile constituents, and OPLS-DA screened 17 key non-volatile differential metabolites with VIP > 1.2. These results indicated that MCZ and BCZ could be clearly separated not only by sensory signals but also by volatile and non-volatile chemical profiles. This study revealed that the differences between MCZ and BCZ are mainly reflected in odor-active volatile compounds, key taste indicators, and non-volatile differential metabolites. The integration of electronic nose, electronic tongue, HS-GC-IMS, and UPLC-Orbitrap MS provides a comprehensive and reliable strategy for distinguishing the two botanical origins of Atractylodis Rhizoma. These findings provide valuable insights into the material basis underlying the sensory and chemical differences between MCZ and BCZ and offer scientific support for accurate authentication, quality evaluation, and rational clinical application of Atractylodis Rhizoma. Full article

Demand for greener and safer chemistries has driven the innovation of bioinspired and enzyme-mimicking catalysts for selective and efficient oxidation and hydrogenation under mild conditions. Natural catalysts, including peroxidases, oxidases, hydrogenases, oxygenases and dehydrogenases, boast remarkable activity, specificity, stability, selectivity, low energy requirements and atom economy. Disadvantages of enzymes, such as poor thermal stability, a narrow operational range, low recovery yield and the expense of purification, are motivating the discovery and design of enzyme substitutes. Several artificial platforms have appeared recently: nanozymes, artificial metalloenzymes, biomimetic metal Complexes, MOFs, atomic catalysts, bioinorganic hybrid systems, among others. These systems aim to replicate key structural and mechanistic features of enzymes while providing greater operational stability, recyclability, and scalability. Recent work has demonstrated the benefit of enzyme mimics in increasing eco-sustainability in reactions such as alcohol oxidation, selective alkane oxidation, waste degradation, catalytic photooxygen activation and biomass waste conversion. Similarly, biomimetic hydrogenation catalysts have shown outstanding activity in asymmetrically hydrogenating chemicals, reducing CO₂ into chemicals, hydrogenation by hydrogen transfer and creating hydrogen through water. Through control of active sites, second coordination sites, defects and electrons/protons in the system, significant gains have been seen in reaction selectivity and frequency of turning over substrate into product. Nanozymes, biohybrid catalysis and artificial catalysts guided by deep learning are further broadening the applications of biomimetic catalysis in oxidation and hydrogenation. The article review aims to provide a summary of the most current progress with bioinspired and enzyme-mimicking catalysts, focusing on catalytic mechanisms, how to design such catalysts, how green chemistry benefits from their development and where further application is likely in the coming years. Full article

An inevitable decrease in oil production from reservoirs all over the world necessitates the application of microbial enhancement of oil recovery (MEOR) technologies. The high total salinity of formation water is a factor strongly suppressing the growth of most industry-applicable strains of hydrocarbon-oxidizing bacteria. The halotolerant strain Ectopseudomonas guguanensis G3 isolated from an oil reservoir (Republic of Kazakhstan) has demonstrated high efficiency of oil degradation and presumable biosurfactant production. The ability of the strain to utilize crude oil, n-alkanes, toluene, and xylene and its resistance to NaCl concentrations up to 6% were shown, as well as a high decrease in the interfacial tension of the culture liquid. Genomic analysis of the strain confirmed its ability to oxidize aromatic oil compounds and a wide range of n-alkanes (with a chain length up to C₃₀) and revealed its potential capabilities to produce alginate, consume nitrate and urea as nitrogen sources, and synthesize betaine as an osmoprotectant. These findings demonstrate the high potential of E. guguanensis strain G3 to be used in oil reservoirs with high-salinity formation water in the biotechnology of oil displacement through oil degradation and in situ microbial metabolite production. Full article

This study aimed to analyze the phytochemical composition of hexane extracts from Bixa orellana L. leaves using multivariate analysis and to evaluate their antimicrobial and antioxidant activities. A total of 74 compounds were identified by Gas chromatography–mass spectrometry (GC-MS) from three cultivars, Peruvian red (PR), Peruvian green (PG), and Criolla (Cr), collected in distinct regions of Campeche, Mexico: Bécal (Be), Calkiní (Ca), and Bacabchén (Ba). The chemical classes identified included sesquiterpenes, sesquiterpenoids, alkanes, quinones, tocopherols, and sterols. Principal component analysis (PCA) indicated a clear separation of PRCa, PRBa, and CrBe from the other samples, with 86% of the total variation explained by 22 components. In PRCa (+)-ledol, (E)-β-farnesene, germacrene D, cis-β-santalene, and α-bisabolol were found abundantly. PRBa showed an abundance of β-elemene and moderate levels of caryophyllene oxide, guaiol, and γ-sitosterol. CrBe contained abundant (−)-spathulenol and phytol. The antimicrobial activity against Staphylococcus aureus showed that PRCa extracts exhibited the largest inhibition zones (23.5 ± 2.12 mm), statistically influenced by geographic origin (p = 0.0005). Conversely, PRBe and PRBa showed higher total polyphenol content and antioxidant activity, with the geographic origin × variety interaction significantly influencing these traits (p < 0.001). The findings highlight the importance of B. orellana, particularly the Peruvian red variety, as a valuable source of bioactive secondary metabolites and underscore the influence of cultivar phenotype and geographic origin on phytochemical variability and its antimicrobial and antioxidant properties. Full article

The addition of calcium oxide (CaO) as an additive to B35 biodiesel enhances molecular modifications through changes in the FAME chemical structure. CaO was dispersed in biodiesel using 48 kHz ultrasonic vibration for 48 hours, inducing an exothermic reaction that generated Ca⁺ and O⁻ ions. These ions primarily affected C–H bonds in CH₃, CH₂, and CH groups, with the strongest impact on CH₃ due to its highest bond energy. This perturbation triggered molecular fragmentation and the formation of acetylenic and sp³ alkane C–H compounds, serving as precursors for new functional groups. The study revealed a potential energy increase of 8.1% for acetylenic C–H chains and 13.2% for sp³ alkane C–H stretching. Full article

Maize (Zea mays L.) is a vital global crop whose productivity is severely threatened by abiotic stresses. Epicuticular waxes provide a hydrophobic barrier that protects land plants from environmental stresses. However, the role of key wax biosynthetic enzymes, such as aldehyde decarbonylase CER1, in maize stress adaptation remains unclear. In this study, we performed a functional characterization of ZmCER1 in maize. Our results show that the overexpression of ZmCER1 in both Arabidopsis and maize substantially improved tolerance to these abiotic stresses. Under stress conditions, the transgenic plants displayed better growth performance, elevated activities of antioxidant enzymes, and reduced levels of oxidative damage markers. Additionally, the alkane content—especially that of C29 and C31—was significantly increased in the ZmCER1OE lines. Through a yeast two-hybrid screening (Y2H screening), we identified the peroxisomal membrane protein ZmPEX14 as an interacting partner of ZmCER1, and the interaction was further confirmed by luciferase complementation (LUC) and bimolecular fluorescence complementation (BiFC) assays. We propose a model wherein ZmCER1 enhances stress tolerance not only by reinforcing the cuticular wax barrier but also by potentially regulating reactive oxygen species (ROS) detoxification via association with ZmPEX14. Collectively, our findings establish ZmCER1 as a key regulator of abiotic stress tolerance in maize and a promising candidate for the molecular breeding of stress-resilient crops. Full article

Microbial biodegradation represents a promising approach to addressing global plastic pollution, yet the metabolic pathways and environmental origins of polymer-degrading microorganisms remain incompletely characterized. This review synthesizes current knowledge on biodegradation mechanisms across major polymer classes and identifies key environmental reservoirs harboring native plastic-degrading microbiota. Biodegradation pathways differ fundamentally according to polymer chemistry. Polyesters such as PET undergo hydrolytic cleavage by PETases and MHETases, releasing terephthalic acid and ethylene glycol for assimilation via the β-ketoadipate pathway and the TCA cycle. Biodegradable polyesters (PLA, PBAT, PHAs, PCL) are similarly hydrolyzed by cutinases, lipases, and depolymerases. In contrast, polyolefins (PE, PP) and polystyrene lack hydrolyzable bonds and require oxidative attack by laccases, peroxidases, and alkane monooxygenases, followed by β-oxidation to acetyl-CoA. Three principal environmental reservoirs supply plastic-degrading microorganisms: contaminated ecosystems including landfills and the plastisphere; soil microbiota contributing ligninolytic fungi and actinomycetes; and compost environments yielding thermostable enzymes such as leaf-branch compost cutinase. Across all environments, microbial consortia demonstrate superior degradation efficiency compared to single-species cultures, reflecting the enzymatic complexity required for complete polymer mineralization. Understanding these pathways and their environmental origins provides a foundation for biological plastic waste management strategies. Full article

The ethylene aromatization (ETA) reaction is a pivotal route for non-petroleum-based aromatics production, yet a systematic understanding of its thermodynamic constraints and kinetic modulation remains elusive. Herein, an integrated thermodynamic and kinetic study is presented to elucidate the temperature-dependent reaction pathways over metal oxide-modified HZSM-5 catalysts. Thermodynamic calculations reveal that while oligomerization, cyclization, and the hydrogen transfer (HT) pathway are exothermic, the aromatics-generating dehydrogenation (DH) pathway is endothermic. Crucially, despite the general thermodynamic penalty imposed by elevated temperatures on most elementary steps, the overall ethylene aromatization reaction retains a strong driving force, underscoring the dehydrogenation pathway as the thermodynamic and kinetic key to aromatic selectivity. Experimentally, it is demonstrated that modifying HZSM-5 with ZnO, Ga₂O₃, and ZnGa₂O₄ effectively tunes the Lewis-to-Brønsted acid (L/B) ratio. A strong linear correlation is established between the L/B ratio and the apparent activation energy, with a higher L/B ratio significantly lowering the activation barrier. This synergistic effect optimally promotes the dehydrogenation pathway, suppresses alkane by-product formation, and maximizes aromatic yield within an optimal temperature window of 470–520 °C. The findings provide a fundamental and practical framework for the rational design of high-efficiency ethylene aromatization catalysts and the optimization of process conditions via targeted acid site engineering. Full article

Despite substantial reductions in precursor emissions, persistent summer ozone (O₃) pollution remains a critical environmental challenge in the North China Plain. This study integrated O₃ and volatile organic compound (VOC) data from the summers of 2014–2020 with an observation-based box model (OBM) to analyze O₃ pollution trends, VOC composition, sources, and sensitivity in Zhengzhou. The results indicated a continuous intensification of summer O₃ pollution, a progressive annual increase in polluted days, and an average annual concentration increase of 6.72 μg m⁻³ yr⁻¹. Further, the average VOC concentration on polluted days was 11.7% higher than that on non-polluted days, with alkanes dominating the component distribution, followed by aromatic hydrocarbons, alkenes, and alkynes. Subsequently, a source-apportionment model (positive matrix factorization) was used to identify six VOC sources: motor vehicle emissions (28.4%), industrial emissions (23.2%), solvent use (16.0%), liquefied petroleum gas/natural gas use (15.8%), fuel combustion (11.4%), and biological sources (5.4%). The photochemical age method corrected VOC loss during atmospheric transport, revealing that the traditional O₃-formation potential (OFP) method underestimated the contributions of alkenes and aromatic hydrocarbons, with isoprene, m/p-xylene, and ethylene as key species. Furthermore, multi-scenario simulations showed that solely reducing nitrogen oxides (NO_x) emissions caused an O₃ concentration rebound, while a 4:1 VOC to NO_x reduction ratio provided optimal control. By identifying the causal drivers of O₃ pollution in Zhengzhou, this study provides a scientific basis for designing precise emission-reduction strategies applicable to the North China Plain and analogous urban regions. Full article

Iso-cetane serves as an ideal component representing branched-chain alkanes in surrogate fuels for diesel. However, the predictive accuracy of existing detailed chemical kinetic models for iso-cetane requires improvement. In this study, focusing on the reaction processes of iso-cetane and its key intermediates, we first updated the thermodynamic data of iso-cetane and some of its intermediates, systematically analyzed the effects of various reactions on ignition delay time (IDT), and made targeted modifications to the relevant reaction rate constants. The reaction types involved include fuel cracking reactions of iso-cetane, hydrogen abstraction reactions, cracking reactions of fuel radicals, as well as the oxidation of fuel radicals, isomerization of alkylperoxy radicals ($\mathrm{R}{\dot{\mathrm{O}}}_2$), concerted elimination reactions, formation of cyclic ethers, and the formation and decomposition of ketohydroperoxides (KHP). Additionally, reactions related to the formation and consumption of p-alkyl-dihydroperoxides ($\dot{\mathrm{P}}{(\mathrm{OOH})}_2$) were supplemented. Based on the above work, we developed a detailed chemical kinetic model for iso-cetane, comprising 4541 species and 18,359 elementary reactions. Through systematic validation against experimental data on ignition delay time and concentration variations of key species during oxidation, the improved predictive performance of the proposed model was demonstrated. Furthermore, using sensitivity analysis and reaction pathway analysis for the ignition process, we revealed that the formation of the low-temperature negative temperature coefficient (NTC) region for iso-cetane is intrinsically associated with the competition between chain-branching and chain-propagating pathways. Full article

Thermal–oxidative coking of aviation fuel remains a critical limitation for fuel-cooled aero-engine systems operating under high heat loads. This study systematically investigates the oxidative coking behavior of RP-3 aviation kerosene, focusing on the coupled evolution of deposit morphology, composition, and operating conditions. Experiments were conducted in an electrically heated stainless-steel tube while independently varying dissolved oxygen concentration, fuel temperature, temperature gradient, operating pressure, and heating duration. Deposit layers were characterized by SEM and XPS, and residual fuel chemistry was analyzed using GC/MS. The results show that dissolved oxygen governs both the extent and mechanism of coking in the autoxidation regime (150–450 °C). Normal and elevated oxygen levels promote autoxidation of straight-chain alkanes, generating oxygen-containing intermediates that form flocculent, oxygen-rich deposits, whereas near-deoxygenated conditions suppress autoxidation but sustain sulfur-dominated, needle-like deposits. Temperature primarily controls deposition rate and morphology, with steep temperature gradients inducing localized coke formation, while pressure exerts only a minor indirect influence. Prolonged operation leads to deposit densification and non-linear accumulation behavior. These findings clarify the links between fuel chemistry, thermal conditions, and deposit architecture, providing a basis for morphology-aware coking models in fuel-cooled aero-engine systems. Full article

Chlorinated paraffins (CPs) are widely used, structurally complex mixtures of chlorinated alkanes whose ecological risks in aquatic ecosystems have raised increasing concern. However, the toxic effects and molecular mechanisms of CPs on primary aquatic producers remain poorly understood. In this study, we used the eukaryotic green algae Chlorella sp. and the prokaryotic cyanobacterium Microcystis aeruginosa (M. aeruginosa) as test organisms to systematically investigate the effects of CPs with different carbon chain lengths, namely short-chain CPs (SCCPs), medium-chain CPs (MCCPs), and long-chain CPs (LCCPs), on algal growth, photosynthetic pigment content, antioxidant systems, cellular ultrastructure, and the underlying molecular responses. Our results showed that CPs toxicity to algae is significantly dependent on both CPs carbon-chain length and algal species. Exposure to 1.0 mg/L SCCPs for 96 h produced a growth inhibition of Chlorella sp. of 14.45%. CPs’ exposure significantly altered algal Chl-a content and elicited antioxidant defense responses, and affected the synthesis and extracellular release of MC-RR and MC-LR in M. aeruginosa. Ultrastructural observations revealed cell surface wrinkling and deformation in both Chlorella sp. and M. aeruginosa. Chlorella sp. additionally exhibited thylakoid disintegration and plasmolysis. Transcriptomic analysis indicated that CPs with different chain lengths significantly downregulated genes in Chlorella sp. associated with DNA replication and mismatch repair, suggesting impairment of replication initiation and elongation and compromised genome stability. Concurrently, genes encoding photosynthetic antenna proteins and carbon fixation were upregulated. In M. aeruginosa, CPs exposure markedly disturbed energy metabolism pathways, including glycolysis/gluconeogenesis and oxidative phosphorylation, which were generally downregulated. This study provides a comparative assessment of CPs’ toxicity between the eukaryotic algae Chlorella sp. and the prokaryotic algae M. aeruginosa, revealing that toxicity is co-determined by carbon chain length and algal species. Additionally, it provides critical toxicological data and establishes a theoretical foundation for the scientific assessment of the aquatic ecological risks posed by CPs with different carbon chain lengths. Full article

This review examines the role of sulfate-reducing bacteria in the anaerobic degradation of hydrocarbons in marine sediments, where they contribute to the mineralization of organic matter under anoxic conditions. The metabolic diversity of these microorganisms is described, including their ability to degrade various classes of hydrocarbons such as short-chain (C₂–C₅), medium-chain (C₆–C₁₂), and long-chain (C₁₃–C₂₀₊) alkanes, alkenes, and aromatic compounds like naphthalene and phenanthrene. The primary mechanisms involved in the initial activation of these hydrocarbons—fumarate addition and carboxylation—are discussed, along with key enzymes, including alkylsuccinate synthase and benzylsuccinate synthase. Syntrophic interactions are also considered, particularly in which archaea initiate the oxidation of short-chain alkanes (e.g., ethane and butane), with sulfate-reducing bacteria serving as terminal electron acceptors via sulfate reduction. The potential application of these anaerobic processes in bioremediation strategies for oil-contaminated marine sediments is discussed. This microbially mediated degradation may offer a complementary approach to aerobic methods, particularly in oxygen-limited environments. Understanding the activity of sulfate-reducing bacteria activity is relevant to several areas: the development of remediation techniques for anoxic zones, the assessment of methane emissions from marine sediments, the management of microbiologically influenced corrosion, and potential biotechnological applications. Current research directions include the study of syntrophic microbial consortia and the exploration of bioelectrochemical systems. Full article