Search Results (1,404)

The escalating global demand for large-scale, cost-effective, and sustainable high-quality protein has positioned single-cell protein (SCP) production from one-carbon (C1) gases as a highly promising solution. In this study, eight chemolithoautotrophic hydrogen-oxidizing bacteria (HOB) were isolated from mangrove sediments. Based on the 16S rRNA gene sequence analysis, they belonged to genera Sulfurimonas, Sulfurovum, Thiomicrolovo, and Marinobacterium. Among these, Thiomicrolovo sp. ZZH C-3 was identified as the most promising candidate for SCP production based on the highest biomass and protein content, and was selected for further characterization. Strain ZZH C-3 is a Gram-negative, short rod-shaped bacterium with multiple flagella. It can grow chemolithoautotrophically by using molecular hydrogen as an energy source and molecular oxygen as an electron acceptor. Genomic analysis further confirmed that ZZH C-3 harbors a complete reverse tricarboxylic acid (rTCA) cycle gene set for carbon fixation, and diverse hydrogenases (Group I, II, IV) for hydrogen oxidation. Subsequently, its cultivation conditions and medium composition for SCP production were systematically optimized using single-factor experiments and response surface methodology (RSM). Results showed that the optimal growth conditions were 28 °C, pH 7.0, and with 1 g/L (NH₄)₂SO₄ as the nitrogen source, 5–10% oxygen concentration, 9.70 mg/L FeSO₄·7H₂O, 0.17 g/L CaCl₂·2H₂O, and 1.90 mg/L MnSO₄·H₂O. Under the optimized conditions, strain ZZH C-3 achieved a maximum specific growth rate of 0.46 h⁻¹. After 28 h of cultivation, the optical density at 600 nm (OD₆₀₀) reached 0.94, corresponding to a biomass concentration of 0.60 g/L, and the protein content ranked at 73.56%. The biomass yield on hydrogen (Y_H2) was approximately 3.01 g/g H₂, with an average H₂-to-CO₂ consumption molar ratio of about 3.78. Compared to the model HOB Cupriavidus necator, strain ZZH C-3 exhibited a lower H₂/CO₂ consumption ratio, superior substrate conversion efficiency, and high protein content. Overall, this study not only validated the potential of mangrove HOB for SCP production but also offers new insights for future metabolic engineering strategies designed to enhance CO₂-to-biomass conversion efficiency. Full article

Heterotrophic nanoflagellates (HNANs) are central components of the microbial loop, transferring carbon from bacteria to higher trophic levels and facilitating nutrient recycling. While many HNANs are free-swimming, some exhibit enhanced feeding efficiency when attached to surfaces, including diatom frustules. Here, we describe the attachment behavior of a novel interception-feeding HNAN affiliated with the order Bicosoecida to centric diatoms common in North Carolina coastal waters. Using growth experiments, live observations, and time-lapse microscopy, we quantified attachment frequency and assessed its influence on diatom growth for three diatom species: Coscinodiscus sp., Odontella sp., and Rhizosolenia sp. HNAN attachment differed significantly among diatom taxa: Coscinodiscus sp. hosted the highest and most sustained numbers per frustule, whereas after normalizing for surface area, Rhizosolenia sp. exhibited the highest attachment efficiency. Diatom peak growth was 1.2 to 2.1-fold higher and occurred earlier in HNAN co-cultures than in controls, indicating microbial recycling by the HNAN stimulated growth. These findings highlight the nuanced ecological role attached HNANs might play as they exploit diatom-associated boundary layers to enhance bacterial encounter rates. The growth trajectories in our lab experiments suggests that attachment behavior in situ can play a role in driving diatom bloom dynamics and, therefore, play an important role for carbon cycling. Full article

Obtaining enzymes through bioconversion depends on a complex relationship between the microorganisms and the biomass used. Here, we evaluate xylanase production by diverse actinobacterial species, cultivated using xylan as the sole carbon source and complex media containing sorghum as the substrate. Fifty-three actinobacteria were tested for xylanase production in a solid medium. Seventeen strains produced xylanase and were tested for their ability to produce xylanase, total cellulases (filter paper activity, FPase), and endoglycanase in submerged culture using a defined liquid medium. The best xylanase-producing species was Streptomyces capoamus, yielding 24 IU·mL⁻¹. For FPase, Streptomyces sp. showed the highest yield (1.12 IU·mL⁻¹); for endoglycanase, the best producer was Streptomyces ossamyceticus (0.99 IU·mL⁻¹). When sweet sorghum was used alone, S. curacoi, S. ossamyceticus, and S. capoamus showed xylanase activities of 4.5 IU·mL⁻¹, 4.4 IU·mL⁻¹, and 0.8 IU·mL⁻¹, respectively. However, FPase activity was not detected under the assay conditions. The results showed that there is an intraspecific difference in xylanase, endoglucanase, and FPase production by actinobacteria, with the species S. curacoi, S. ossamyceticus, and S. capoamus able to use sorghum as a carbon source, demonstrating biotechnological potential. Full article

In this study, we develop a game-theoretic optimization framework to analyze competing vessels’ technology choices between shore power (SP) and low-sulfur fuel oil (LSFO) within a maritime supply chain which is regulated by a cap-and-trade mechanism. Using a Stackelberg game approach, we construct two models—one port-led and the other vessel-led—to derive closed-form equilibrium for pricing, service quantities, profits, emissions, and social welfare. The results reveal three key findings. First, the leader in either Stackelberg structure always achieves higher profits, while total supply chain profits remain identical across power structures. Second, at low carbon prices, LSFO-equipped vessels provide more services and earn higher profits due to cost advantages. As the carbon price rises—which directly incentivizes emission reduction and accelerates maritime decarbonization—SP becomes more attractive and eventually dominates in profitability despite higher initial investment. Notably, although SP has lower unit emissions, its total emissions may surpass those of LSFO at certain carbon-price thresholds because the SP-equipped vessel optimally expands output. Third, intensified competition reduces service quantities, profits, and emissions, with a more substantial reduction effect on LSFO vessels. Overall, our results provide mathematically grounded insights for optimizing low-carbon technology adoption in maritime transport and offer actionable policy implications for carbon pricing that balance environmental objectives and supply chain efficiency. This research contributes specifically to the United Nations’ Sustainable Development Goals (SDGs), specifically SDG 13 (Climate Action) and SDG 9 (Industry, Innovation and Infrastructure). Full article

The rapid rise in atmospheric CO₂ necessitates strategies for mitigation and valorization. Microalgae offer potential through simultaneous CO₂ capture and production of high-value biomolecules. Five Chlorophyta strains (A–E: Micractinium sp., Chlamydomonas sp., Micractinium sp., Chlorococcum sp., and Chlorella vulgaris) were isolated from temperate waters and soils and tested for growth and biochemical responses under controlled nitrogen availability (low: 0.346 g L⁻¹ nitrate; high: 0.6 g L⁻¹ nitrate + ammonia), carbon supply (low: 0.04% CO₂; high: 4% CO₂), and cultivation systems (batch reactors, fermenters, and varied illumination). Over 14 days, maximum dry biomass was achieved in batch cultivation with CO₂ sparging, low nitrogen, and continuous light, ranging from 1.47 g L⁻¹ (strain A) to 2.67 g L⁻¹ (strain D). Biomass composition varied: proteins, 25–45%; carbohydrates, 20–35%; and lipids, 18–28%. Nitrogen limitation promoted lipid accumulation (e.g., strain D: +40%) with concurrent protein decline (−25%). Chlorophyll a/b displayed strain-specific plasticity; high CO₂ generally increased chlorophyll, while nitrogen stress reduced it up to 50%. Overall, this study demonstrates that locally adapted Chlorophyta strains can achieve high biomass productivity under CO₂ enrichment while allowing for flexible redirection of carbon flux toward lipids, carbohydrates, or pigments through nutrient management. Among the tested isolates, strains D and E emerged as the most promising candidates for integrated CO₂ sequestration and biomass production, while strains B, C, and D showed strong potential for biodiesel feedstock; strain A for carbohydrate valorization; and strain E for chlorophyll extraction. Future research should focus on scale-up validation in pilot photobioreactors under continuous operation, optimization of two-stage cultivation strategies for lipid production, integration with industrial CO₂ point sources, and strain improvement using modern genomics-assisted breeding and genome-editing technologies. These efforts will support the translation of regional microalgal resources into scalable carbon-capture and bioproduct platforms. Full article

Carbon quantum dots (CQDs) have attracted intense research interest due to their unique physicochemical properties and broad application potential. CQDs are a new class of ultrasmall fluorescent carbon nanoparticles (<10 nm) that exhibit bright photoluminescence, broad excitation spectra, high quantum yields (QYs), and excellent photostability. Structurally, they consist of graphitic sp²/sp³-hybridized carbon with amorphous or nanocrystalline cores. Unlike conventional semiconductor quantum dots (SQDs), which often contain toxic group II–VI, III–VI, or IV–VI elements, CQDs offer a safer and more environmentally friendly alternative for biomedical and cosmetic applications. This review summarizes recent advances in green-chemistry approaches for CQD synthesis, including top-down, bottom-up, waste-derived, and surface-functionalization methods. Particular attention is given to natural carbon sources, which provide low-cost, sustainable, and eco-friendly routes for scalable production. The optical, electronic, and toxicological properties of CQDs are discussed to clarify their performance and safety profiles. Special emphasis is placed on their emerging roles in wound healing and cosmetic formulations, which remain underexplored despite their promising potential. To our knowledge, this is the first comprehensive review focusing on the current progress, key challenges, and future perspectives of CQDs in beauty and personal care applications. Full article

This study investigates the interface between cement hydration, low-field NMR relaxometry, and the incorporation of carbon-based fillers into cementitious materials. The objective is to provide NMR-based insights into how carbon black (CB) and an acrylic superplasticizer (SP) influence cement hydration and the resulting microstructural evolution. CB was integrated into white Portland cement (WPC) using both wet and dry mixing approaches, with water content and SP dosage varied independently. First, water-based “inks” containing different SP/CB weight ratios were prepared and evaluated through dynamic light scattering (DLS) and ζ-potential measurements to assess colloidal stability and dispersibility. For the wet-mixing route, an in situ NMR experiment was performed to monitor the progressive incorporation of carbon ink into cement pastes while increasing the water content. The ability to distinguish ink-related signals from those originating from the cement paste represents a promising step toward non-destructive assessments of carbon dispersion in fresh pastes. Separately, ex situ NMR measurements were performed on samples extracted from dry-mixed pastes with various SP dosages. These experiments mark the SP-induced delay in hydration and the refinement of the pore network that is also associated with improved particle dispersion. Complementary optical microscopy (OM) and ultrasonic pulse velocity (UPV) measurements on hardened samples corroborate the NMR findings. Full article

Background: Occupational exposure to aerosol particles can pose a substantial health risk. The study aimed to characterise the deposition of occupationally relevant aerosols in a 3D anatomical adult nasal cavity model under steady and unsteady flows. Materials: The deposition of aerosolised wheat flour, pine wood sanding dust, carbon black, and Arizona Test Dust A3 was quantified under steady flows (5, 7.5, and 20 L/min per nostril) and an unsteady breathing pattern generated by the commercial breathing simulator. Image analysis with custom software quantified the area covered by deposited particles. The Downstream Penetration Index (DPI) was determined from the outlet mass. Results: The highest segmental deposition occurred in the anterior segment of the lateral wall (WA) and septum (SA), with moderate values in the middle lateral wall (WM) and the lowest in the posterior lateral wall (WP, nasopharynx) and septum (SP). Arizona Test Dust A3 and carbon black demonstrated higher middle-posterior deposition and DPI, consistent with finer particle size distributions (PSD) and greater sub-10 µm fractions. In contrast, wheat flour and pine wood dust, with larger median particle sizes and lower sub-10 µm fractions, showed stronger anterior filtration and lower DPI. Increased flow enhanced anterior filtration of coarse particles and shifted deposition forward, aligning with increased inertial impaction, but elevated DPI for fine particles. Under unsteady flow, deposition was intermediate between 7.5 and 20 L/min. Conclusions: This study shows that PSD, morphology, and flow conditions influence nasal deposition. Coarse aerosols were filtered in the anterior nose, while fine-rich aerosols showed relatively greater middle-posterior deposition and higher DPI. These findings are essential for assessing occupational exposure and developing interventions and prevention strategies. Full article

Background/Objectives: Respiratory dysfunction in Parkinson’s disease (PD) is frequently underrecognized, particularly when resting oxygen saturation is preserved. Dynamic stress testing, however, may reveal exercise-induced oxygen desaturation, reflecting a latent functional respiratory impairment. The relationship between exertional oxygen desaturation and cognitive performance in PD remains insufficiently explored. Objective: To investigate the association between exercise-induced oxygen desaturation and global cognitive performance in patients with PD, and to explore the contribution of pulmonary gas exchange impairment assessed by diffusing capacity of the lung for carbon monoxide (DLCO). Methods: This prospective, cross-sectional, single-center observational study with consecutive enrollment included 50 patients with idiopathic Parkinson’s disease undergoing multidisciplinary respiratory evaluation following neurological assessment. Participants underwent cognitive evaluation using the Romanian version of the Montreal Cognitive Assessment (MoCA), pulmonary function testing including DLCO and total lung capacity (TLC), and a supervised 6-min walk test (6MWT) with continuous pulse oximetry. Exercise-induced oxygen desaturation was defined as a decrease in SpO₂ of ≥4% from baseline. Correlation analyses and multivariable regression models were applied. Results: Exercise-induced oxygen desaturation was frequent, with 60% of patients exhibiting a ≥4% decrease in SpO₂ during the 6MWT. Greater desaturation was significantly associated with lower MoCA scores (Spearman’s r = −0.383, p = 0.006). No significant associations were found between exertional desaturation and resting pulmonary function parameters, including DLCO and TLC. In multivariable analysis, lower MoCA score and levodopa–carbidopa intestinal gel treatment independently predicted greater oxygen desaturation during exercise. Conclusions: Exercise-induced oxygen desaturation is common in patients with PD despite preserved resting oxygenation and is associated with poorer cognitive performance. These findings suggest that exertional desaturation may reflect a dynamic functional impairment and may be associated with increased physiological vulnerability. Functional exercise testing with oxygen saturation monitoring may provide complementary information beyond resting pulmonary assessments. Full article

To address the high-carbon emissions associated with the large use of Portland cement (PC) in traditional engineered cementitious composites (ECCs) and the resource constraints on supplementary cementitious materials (SCMs), this study proposes a strategy combining limestone calcined clay cement (LC³) as a PC replacement with the incorporation of hybrid synthetic fibers to develop low-carbon, environmentally friendly ECCs. The fundamental properties of the LC³-ECC were tested, and a sustainability analysis was conducted. The experimental results show that an increase in water-to-binder ratio (W/B) or superplasticizer (SP) dosage significantly enhanced fluidity while reducing the yield stress and plastic viscosity. An LC³-ECC with a W/B of 0.25, 0.45% SP and 2% polyethylene fibers exhibited the best tensile performance, achieving an ultimate tensile strain of 8.40%. In contrast, an increase in polypropylene fiber led to a degradation in crack-resistant properties. In terms of sustainability, replacing the PC with LC³ significantly reduced carbon emissions by 19.1–20.8%, while the cost of the limestone calcined clay cement–polypropylene fiber (LC³-PP) was approximately 50% of that of the limestone calcined clay cement–polyvinyl alcohol fiber (LC³-PVA). Furthermore, an integrated evaluation framework encompassing rheological, mechanical and environmental factors was established using performance radar charts. The dataset on the performance results and the developed assessment framework provide a foundation for optimizing the mixture proportioning of LC³-ECC in practical engineering applications. Full article

The synthesis of carbon dots (CDs) from coal represents a promising strategy for advancing both the efficient, low-carbon utilization of coal resources and the cost-effective production of CDs. To enable the controlled, high-quality conversion of CDs from coal, a comprehensive understanding of the relationship between the coal chemical structure and the properties of CDs is crucial. This study prepared CDs from nine kinds of coal using a chemical oxidation method, and the correlations between properties of coal-based carbon dots and the original materials were revealed. The results show that the luminescence sites of coal-derived CDs are mostly distributed around 435 nm or 500 nm, where the former one relates to the confined sp² domains and the latter one is associated with the defect structure. Coal with a volatile content of about 20–30% in the nine samples was found to produce higher CD yields, with a maximum mass yield of 19.96%, accompanied by stronger fluorescence intensity. During chemical oxidation processes, the unsaturated double bonds (C=C, C=O) and aliphatic chains firstly break, and then aromatic clusters are formed by dehydrocyclization between carbon crystallites, followed by the introduction of a C–O group. The growth of the C–O group in the CDs contributes to a stronger fluorescence property. Furthermore, strong correlations were found between the carbon skeleton structure of raw coal and photoluminescence characteristics of corresponding CDs, as reflected by Raman parameters A_D1/A_G, I_D1/I_G, and FWHM_D. The findings offer significant insights into the precise modulation and control of coal-based carbon dot structures. Full article

Today, PHB and its copolymers—potential plastic substitutes—are produced by fermenting sugar, which is not scalable to the volumes of plastic consumption. PHB from CH₄ can offer a sustainable process route, with CH₄ potentially produced from a variety of waste biomass streams through anaerobic digestion, gasification, and methanation. The high molar mass (M_w) of PHB is a key determinant of its mechanical properties, and strain, culture conditions and downstream processing influence it. In this work, the strain Methylocystis sp. GB 25 (DSMZ 7674) was grown on natural gas as the sole carbon and energy source and air (1:1) in a loop reactor with 350 L active fermentation volume, at 35 °C and ambient pressure. After two days of continuous growth, the bacteria were limited in P and N for 1, 2, and 2.5 days to determine the optimal conditions for PHB accumulation and the highest Mw as the target. The biomass was then centrifuged and spray-dried. For downstream processing, chloroform solvent extraction and selected enzymatic treatment were deployed, yielding ~40% PHB from the biomass. The PHB obtained by solvent extraction exhibited high average weight molar masses of M_w ~1.1–1.5 × 10⁶ g mol⁻¹. The highest M_w was obtained after one day of limitation, whereas enzyme treatment resulted in partially degraded PHB. Cold chloroform maceration, interesting due to energy savings, did not achieve sufficient extraction efficiency because it was unable to extract high-molar-mass PHB fractions. The extracted PHB has a high molar mass, more than double that of standard commercial PHB, and was characterized by DSC, which showed a high degree of crystallinity of up to 70% with a melting temperature of close to 180 °C. Mechanical tensile properties measurements, as well as dynamic mechanical thermal analysis (DMTA), were performed. Degradation of the PHB by enzymes was also determined. Methanotrophic PHB is a promising bioplastics material. The high M_w can limit and delay polymer degradation in practical processing steps, making the material more versatile and robust. Full article

Orchid seed germination requires symbiotic association with mycorrhizal fungi that provide essential nutrients for germination and subsequent growth. Extensive research has elucidated the pivotal role of the mycorrhizal fungus Tulasnella sp. in the modulation of seed germination and growth processes in Bletilla striata (Thunb.) Reiehb.f. However, the molecular mechanisms underlying this symbiosis remain poorly characterized. Our integrated transcriptomic-metabolomic analysis of symbiotic germination revealed that co-cultivation of Tulasnella sp. bj1 with B. striata seeds significantly downregulates the expression of plant-derived flavonoid biosynthetic genes, with flavonoid degradation potentially alleviating germination and growth inhibition. The bj1 strain modulates indoleacetic acid (IAA) biosynthesis in B. striata by upregulating the expression of plant-derived tryptophan decarboxylase (TDC) in the tryptophan pathway and hydrolytic enzymes (NtAMI) in the indoleacetamide pathway, with elevated IAA potentially contributing to seed germination and growth. Moreover, bj1 suppresses the jasmonic acid (JA) biosynthetic pathway of B. striata by downregulating key plant-derived biosynthetic genes, concurrently promoting the accumulation of 12-hydroxyjasmonic acid—a metabolite associated with plant immune regulation that may favor colonization and symbiotic establishment with B. striata seeds. Additionally, bj1 induces the expression of polysaccharide-degrading enzymes, potentially improving carbon source utilization to support protocorm development. In conclusion, bj1 modulates the immune response of B. striata seeds, facilitating the establishment of a symbiotic relationship. Subsequently, the germination and growth of B. striata seeds are enhanced through reduced flavonoid accumulation, increased IAA synthesis, and improved carbon source utilization. Consequently, this investigation provides a crucial foundation for elucidating mechanisms governing symbiotic germination in B. striata. Full article

Tillage practices regulate soil health by influencing soil’s physico-chemical qualities and its capacity to sequester organic carbon. Maintaining soil health contributes to ecosystem stability and fluidity in the soil–plant–atmosphere relationship. This study aimed to evaluate soil porosity (SP), aeration limit (SAL), soil capillary capacity (SCC), soil total capacity (STC), soil temperature (Ts), air temperature (Ta), nutrient availability, soil organic carbon (SOC), and soil organic matter (SOM) under three different tillage systems: no-tillage (NT), minimum tillage (MT), and conventional tillage (CT), based on a short-term field experiment. This research was conducted on Cambic Chernozem soil using a randomized complete block design with three replications. The results revealed a significant effect of tillage systems on all evaluated properties. SP reached a higher value under MT (60.01%), NT (56.74%) and CT (53.58%), respectively. This observation is similar with regard to SAL, SCC, and STC. It might be due to the reduced soil disturbance characteristics of conservation systems, thereby maintaining the soil’s natural state. There is a positive regression between these two properties across all three systems, with the highest R² = 0.8308 observed under MT. The highest carbon stocks were recorded in NT (2.82%) and MT (2.91%) compared to 2.01% in CT at surface depths of 0–5 and 5–10 cm. This can be explained by the accumulation of organic residues and a reduction in their oxidation. Nutrient availability (TN, P, and K) increased at depths of 0–5 cm and 5–10 cm, with the highest values in conservation systems. Furthermore, the results demonstrate a significant relationship and positive synergy between soil depth, tillage practices, and key physical and chemical soil properties, especially carbon stock, across the two cropping seasons. Full article

Actinidia deliciosa is a globally important economic fruit crop, and its fruit quality and yield are profoundly influenced by light and environmental conditions. Sucrose phosphate synthase (SPS), a key rate-limiting enzyme in the sucrose biosynthesis pathway, plays a central role in regulating carbon metabolism and sucrose accumulation in plants. However, comprehensive studies of the SPS gene family in A. deliciosa are still lacking, particularly regarding its expression in response to different light qualities. In this study, genome-wide identification of the SPS gene family in A. deliciosa was conducted using bioinformatics approaches. A total of 31 SPS genes were identified and named AdSPS1 to AdSPS31 on the basis of their chromosomal positions. The encoded proteins were predicted to be acidic, hydrophilic, and primarily localized in the chloroplast. All the AdSPS proteins contained the conserved domains Sucrose_synth, Glyco_trans_1, and S6PP, indicating potential roles in sucrose metabolism. Phylogenetic analysis classified the 31 AdSPS members into three subfamilies, A, B, and C, comprising 20, 5, and 6 members, respectively. Collinearity analysis revealed extensive syntenic relationships among AdSPS genes across different chromosomes, suggesting that gene duplication events contributed to the expansion of this gene family. Promoter cis-acting element analysis revealed that light-responsive elements were the most abundant among all the detected elements in the upstream regions of the AdSPS genes, implying potential regulation by light signals. Different light qualities significantly affected the contents of sucrose, glucose, and fructose, as well as SPS activity in kiwifruit leaves, with the highest activity observed under the R3B1 (red–blue light 3:1) treatment. Spearman’s correlation analysis indicated that AdSPS3 was significantly negatively correlated with sucrose, fructose, glucose, and SPS activity, suggesting a potential role in negatively regulating sugar accumulation in kiwifruit leaves, whereas AdSPS12 showed positive correlations with these parameters, implying a role in promoting sucrose synthesis. To further explore the light response of the AdSPS genes, eight representative members were selected for qRT‒PCR analysis under red light, blue light, and combined red‒blue light treatments. These results demonstrated that light quality significantly influenced SPS gene expression. Specifically, AdSPS6 and AdSPS24 were highly responsive to R1B1 (1:1 red‒blue light), AdSPS9 was significantly upregulated under R6B1 (6:1 red‒blue light), AdSPS21 was strongly induced by blue light, and AdSPS12 expression was suppressed. This study systematically identified and analyzed the SPS gene family in A. deliciosa, revealing its structural characteristics and light-responsive expression patterns. These findings suggest that AdSPS genes may play important roles in light-regulated carbon metabolism. These results provide a theoretical foundation and valuable genetic resources for further elucidating the molecular mechanisms of sucrose metabolism and light signal transduction in kiwifruit. Full article