Enzymatic conversion of carbon dioxide (CO2) to fuel or chemicals is appealing, but is limited by lack of efficient technology for regeneration and reuse of expensive cofactors. Here we show that ...cationic polyelectrolyte-doped hollow nanofibers, which can be fabricated via a facile coaxial electrospinning technology, provide an ideal scaffold for assembly of cofactor and multienzymes capable of synthesizing methanol from CO2 through a cascade multistep reaction involving cofactor regeneration. Cofactor and four enzymes including formate, formaldehyde, alcohol, and glutamate dehydrogenases were in situ coencapsulated inside the lumen of hollow nanofibers by involving them in the core-phase solution for coaxial electrospinning, in which cationic polyelectrolyte was predissolved. The polyelectrolyte penetrating across the shell of the hollow nanofibers enabled efficient tethering and retention of cofactor inside the lumen via ion-exchange interactions between oppositely charged polyelectrolytes and cofactor. With carbonic anhydrase assembled on the outer surface of the hollow nanofibers for accelerating hydration of CO2, these five-enzymes-cofactor catalyst system exhibited high activity for methanol synthesis. Compared with methanol yield of only 36.17% using free enzymes and cofactor, the hollow nanofiber-supported system afforded a high value up to 103.2%, the highest reported value so far. It was believed that the linear polyelectrolytes acted as spacers to enhance the shuttling of cofactor between enzymes that were coencapsulated within near vicinity, thus improving the efficiency of the system. The immobilized system showed good stability in reusing. About 80% of its original productivity was retained after 10 reusing cycles, with a cofactor-based cumulative methanol yield reached 940.5%.
Great progress has been made in the preparation and application of multi-shelled hollow micro-/nanostructures during the past decade. However, the synthetic methodologies and potential applications ...of these novel and interesting materials have not been reviewed comprehensively in the literature. In the current review we first describe different synthetic methodologies for multi-shelled hollow micro-/nanostructures as well as their compositional and geometric manipulation and then review their applications in energy conversion and storage, sensors, photocatalysis, and drug delivery. The correlation between the geometric properties of multi-shelled hollow micro-/nanostructures and their specific performance in relevant applications are highlighted. These results demonstrate that the geometry has a direct impact on the properties and potential applications of such materials. Finally, the emerging challenges and future development of multi-shelled hollow micro-/nanostructures are further discussed.
A major challenge in vaccine formulations is the stimulation of both the humoral and cellular immune response for well-defined antigens with high efficacy and safety. Adjuvant research has focused on ...developing particulate carriers to model the sizes, shapes and compositions of microbes or diseased cells, but not antigen fluidity and pliability. Here, we develop Pickering emulsions-that is, particle-stabilized emulsions that retain the force-dependent deformability and lateral mobility of presented antigens while displaying high biosafety and antigen-loading capabilities. Compared with solid particles and conventional surfactant-stabilized emulsions, the optimized Pickering emulsions enhance the recruitment, antigen uptake and activation of antigen-presenting cells, potently stimulating both humoral and cellular adaptive responses, and thus increasing the survival of mice upon lethal challenge. The pliability and lateral mobility of antigen-loaded Pickering emulsions may provide a facile, effective, safe and broadly applicable strategy to enhance adaptive immunity against infections and diseases.
A heterogeneous WS2/g-C3N4 composite photocatalyst was prepared by a facile ultrasound-assisted hydrothermal method. The WS2/g-C3N4 composite was used for photocatalytic regeneration of NAD+ to NADH, ...which were coupled with dehydrogenases for sustainable bioconversion of CO2 to methanol under visible light irradiation. Compared with pristine g-C3N4 and the physical mixture of WS2 and g-C3N4, the fabricated WS2/g-C3N4 composite catalyst with 5 wt% of WS2 showed the highest activity for methanol synthesis. The methanol productivity reached 372.1 μmol h−1 gcat−1, which is approximately 7.5 times higher than that obtained using pure g-C3N4. For further application demonstration, the activity of the WS2/g-C3N4 composite catalyst toward photodegradation of Rhodamine B (RhB) was evaluated. RhB removal ratio approaching 100% was achieved in 1 hour by using the WS2/g-C3N4 composite catalyst with 5 wt% of WS2, at an apparent degradation rate approximately 2.6 times higher than that of pure g-C3N4. Based on detailed investigations on physiochemical properties of the photocatalysts, the significantly enhanced reaction efficiency of the WS2/g-C3N4 composite was considered to be mainly benefiting from the formation of a heterojunction interface between WS2 and g-C3N4. Upon visible-light irradiation, the photo-induced electrons can transfer from the conduction band of g-C3N4 to WS2, thus recombination of electrons and holes was decreased and the photo-harvesting efficiency was enhanced.
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•IWWTPs bacterial communities exhibited a clear species abundance distribution.•Deterministic processes dominate IWWTPs bacterial communities assembly.•Different IWWTPs harbor unique ...core bacterial community.•IWWTP bacterial community was strongly linked to activated sludge function.
Microbial communities are responsible for biological treatment of many industrial wastewater, but our knowledge of their diversity, assembly patterns, and function is still poor. Here, we analyzed the bacterial communities of wastewater and activated sludge samples taken from 11 full-scale industrial wastewater treatment plants (IWWTPs) characterized by the same process design but different wastewater types and WWTP compartments. We found significantly different diversity and compositions of bacterial assemblages among distinct wastewater types and IWWTPs compartments. IWWTPs bacterial communities exhibited a clear species abundance distribution. The dispersal-driven process was weak in shaping IWWTP communities. Meanwhile, environmental and operating conditions were important factors in regulating the structure of the activated sludge community and pollutants removal, indicating that bacterial community was largely driven by deterministic mechanisms. The core microbial community in IWWTPs was different from that in municipal wastewater treatment plants (MWWTPs), and many taxa (e.g. the genus Citreitalea) rarely were detected before, indicating IWWTPs harbored unique core bacterial communities. Furthermore, we found that bacterial community compositions were strongly linked to activated sludge function. These findings are important to both microbial ecologists and environmental engineers, who may optimize the operation strategies jointly for maintaining biodiversity, which in turn may promote a more stable performance of the IWWTP. Overall, our study enhances the mechanistic understanding of the IWWTP microbial community diversity, assembly patterns, and function, and provides important implications for microbial ecology and wastewater treatment processes.
•Performances of media as function of pore-to-adsorbate size ratio were studied•Proteins with large span of radius ranges from 2.9 nm to 14.1 nm were studied•The best ratio of pore-to-adsorbate size ...was dependent on the protein size•Large protein needs greater pore-to-adsorbate size ratio•The study provides guidance to select suitable adsorbent for a given protein
Two commercially available agarose ion exchange media, DEAE-Capto and DEAE-Sepharose FF (DEAE-FF), and two gigaporous media DEAE -AP-120 nm and DEAE-AP-280 nm were evaluated for their applicability in adsorption of five proteins with large span of radius ranges from 2.9 nm to 14.1 nm, which include ovalbumin, bovine serum albumin (BSA), haptoglobin, thyroglobulin and hepatitis B surface antigen (HBsAg) virus like particle. The average pore radius of the four media was determined to be 6.9 nm, 18.5 nm, 59.4 nm and 139.3 nm, respectively, which was obtained by log normal distribution for DEAE-Capto and DEAE-FF and by bimodal Gaussian distribution for the two DEAE-AP media. The performance of these four media including phase ratio, static and dynamic binding capacity, and transport properties for the adsorption of these five model proteins as function of pore-to-adsorbate size ratio were investigated and compared. The best ratio of pore-to-adsorbate size was found dependent on the protein size. For protein with radius from 2.9 nm (ovalbumin) to 5.4 nm (BSA), the agarose media was superior to gigaporous media. Both the static and dynamic adsorption capacities reduced with the increase of pore size, and the highest values were obtained at the smallest pore-to-adsorbate size of about 2 times in this study, although the highest accessible surface area was obtained at pore-to-adsorbate size ratio about 16 to 20. For proteins with radius of 5.4 nm or larger than that, their adsorption capacities decreased firstly and then increased with the increase of ratio of pore-to-adsorbate size, and the highest values were obtained on the gigaporous media DEAE-AP-280 nm, which could provide faster diffusivity and larger accessible surface area. However, protein with radius of 14.1 nm (HBsAg) had much lower capacities compared to other proteins at the same pore-to-adsorbate size ratio, implying large protein needs greater pore-to-adsorbate size ratio to achieve a satisfactory capacity. For all the five tested proteins, the DEAE-Capto media having the smallest pore radius and branched dextran chains, was found superior to DEAE-FF in terms of both higher adsorption capacities and uptake kinetics, which suggested that the “chain delivery effect” took place on proteins over large size span from ovalbumin to HBsAg, though the effect on the larger proteins was much less significant than that on the smaller ones. Results from the present work provided more information on how do the relationships of pore size of chromatography media and adsorbate size interactively affect the chromatography behaviors, thus will provide general guidance for selection of suitable adsorbent for biologics of a given size.
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•PBTR framework for priority antibiotic screening was established for the first time.•Resistance risk was incorporated into environmental risk assessment of antibiotics.•A list of 74 ...antibiotics in Chinese seawater from 2000 to 2021 was established.•Priority antibiotics have been identified in the four seas of China for the first time.
Antibiotics are emerging pollutants that have detrimental effects on both target and non-target organisms in the environment. However, current methods for environmental risk assessment primarily focus on the risk to non-target organisms in ecosystems, overlooking a crucial risk of antibiotics - the induction of resistance in targeted bacteria. To address this oversight, we have incorporated resistance (R) risk with persistence, bioaccumulation and toxicity (PBT) to establish a more comprehensive PBTR (persistence, bioaccumulation, toxicity, and resistance) framework for antibiotic-specific risk assessment. Using the PBTR framework, we evaluated 74 antibiotics detected in Chinese seawater from 2000 to 2021, and identified priority antibiotics. Our analysis revealed that the priority antibiotics with R risk accounted for the largest proportion (50% to 70%), followed by P risk (40% to 58%), T risk (16% to 35%) and B risk (0 to 13%). To further categorize these priority antibiotics, we assigned them a risk level according to their fulfillment of criteria related to P, B, T, and R. Antibiotics meeting all four indicators were classified as Grade I, representing the highest risk level. Grade II and Grade III were assigned to antibiotics meeting three or two indicators, respectively. Antibiotics meeting only one indicator were classified as Grade IV, representing the lowest risk level. The majority of priority antibiotics fell into Grade IV, indicating low risk (55% to 79%), followed by Grade III (16% to 45%). The highest risk antibiotic identified in this study was clindamycin (CLIN), categorized as Grade II, in the East China Sea. Our findings aligned with previous studies for 25 antibiotics, affirming the validity of the PBTR framework. Moreover, we identified 13 new priority antibiotics, highlighting the advancement of this approach. This study provides a feasible screening strategy and monitoring recommendations for priority antibiotics in Chinese seawater.
The metabolic processes involved in simultaneous production of vitamin B
12
and propionic acid by
Propionibacterium freudenreichii
are very complicated. To further investigate the regulatory ...mechanism of this metabolism, a simplified metabolic network was established. The effects of glucose feeding, propionic acid removal, and 5,6-dimethylbenzimidazole (DMB) addition on the metabolic flux distribution were investigated. The results showed that synthesis of propionic acid can be increased by increasing the metabolic flux through the oxaloacetate and methylmalonyl-CoA branches in the early and middle stages of the coupled fermentation. After DMB addition, the synthesis of vitamin B
12
was significantly enhanced via increased metabolic flux through the δ-aminolevulinate branch, which promoted the synthesis of uroporphyrinogen III, a precursor of vitamin B
12
. Therefore, the analysis of metabolic flux at key nodes can provide theoretical guidance for the optimization of
P. freudenreichii
fermentation processes. In an experimental coupled fermentation process, the concentrations of vitamin B
12
and propionic acid reached 21.6 and 50.12 g/L respectively, increased by 105.71% and 73.91% compared with batch fermentation, which provides a new strategy for industrial production.
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•Coastal area is an ideal platform for studying antibiotic resistome from the “One Health” perspective.•Land-based wastewater disposal exports ARGs with higher diversity and abundance ...to sea.•Industrial WWTP effluent might be the source of highest antibiotic resistome risk.•mcr-4 and mcr-5 derived from industrial effluent were enriched in the ERA sediments.•HGT potential was higher between microbiome of industrial effluent and its ERA sediments.
Wastewater treatment plants (WWTPs) have been regarded as an important source of antibiotic resistance genes (ARGs) in environment, but out of municipal domestic WWTPs, few evidences show how environment is affected by industrial WWTPs. Here we chose Hangzhou Bay (HZB), China as our study area, where land-based municipal and industrial WWTPs discharged their effluent into the bay for decades. We adopted high-throughput metagenomic sequencing to examine the antibiotic resistome of the WWTP effluent and coastal sediment samples. And we proposed a conceptual framework for the assessment of antibiotic resistome risk, and a new bioinformatic pipeline for the evaluation of the potential horizontal gene transfer (HGT) frequency. Our results revealed that the diversity and abundance of ARGs in the WWTP’s effluent were significantly higher than those in the sediment. Furthermore, the antibiotic resistome in the effluent-receiving area (ERA) showed significant difference from that in HZB. For the first time, we identified that industrial WWTP effluent boosted antibiotic resistome risk in coastal sediment. The crucial evidences included: 1) the proportion of ARGs derived from WWTP activated sludge (WA) was higher (14.3 %) and two high-risky polymyxin resistance genes (mcr-4 and mcr-5) were enriched in the industrial effluent receiving area; 2) the HGT potential was higher between resistant microbiome of the industrial effluent and its ERA sediment; and 3) the highest resistome risk was determined in the industrial effluent, and some biocide resistance genes located on high-risky contigs were related to long-term stress of industrial chemicals. These findings highlight the important effects of industrial activities on the development of environmental antimicrobial resistance.
•Reveals a unique temperature-dependent adsorption behavior of cellulase on lignin.•Evaluation of effect of unproductive enzyme adsorption on the effectiveness of cellulase.•In-depth understanding of ...the recalcitrance of biomass against enzymatic hydrolysis.•Insights on the process of enzymatic hydrolysis of pretreated biomass.
Unproductive enzyme adsorption is an important factor in addition to steric hindrance of lignin that limits the enzymatic hydrolysis of lignocellulosic biomass. While both are important factors, enzymatic hydrolysis of pretreated biomass is most likely conducted in the presence of certain amount of lignin residues that may not necessarily present accessibility hindrance, but can competitively absorb the enzyme. This paper presents a study with purified lignin samples to elucidate the role of unproductive enzyme adsorption. It appeared that lignin adsorbed cellulase quickly at 4°C with adsorption equilibrium reached within 1h, similar to that observed for crystalline cellulose. Increasing temperature to 50°C (typical hydrolytic reaction condition) facilitated the rate of cellulase adsorption on cellulose with a peak of adsorption reached at 0.25h; however, adsorption on lignin was surprisingly slower and took over 12h to reach equilibrium, which was accompanied with a 10-fold increase in adsorption capacity. Despite the high adsorption capacity of lignin (which is comparable to that of cellulose) at 50°C, the presence of added lignin imposed only minimal impact on the enzyme apparent activity, most likely due to the slow adsorption kinetics of lignin.
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