Based on the beneficial effects of magnesium ions on biomolecules, it was first introduced into enzyme immobilization carriers to promote the comprehensive performance of immobilized enzymes in ...repeated use. Firstly, Fe3O4 nanoparticles (NPs) were prepared by the inverse microemulsion method, then, Mg2+ was doped in the process of coating β-cyclodextrin (β-CD) on the surface of Fe3O4 NPs. Afterward, through acetal reaction, glutaraldehyde (GA) was grafted to the material’s surface to obtain Mg2+-Fe3O4 @ β-CD-g-GA NPs, and covalent bond immobilization of Penicillin G acylase (PGA) was realized by the Schiff base reaction of the carriers’ aldehyde group and PGA’s amino group. After optimization of process conditions, the results show that the performances of the immobilized PGA achieve the best, when the concentration of the enzyme solution is 3.00 vol%, pH is 8.0, the immobilization time is 30 h, and the immobilization temperature is 37 °C. Its enzyme activity recovery (EAR), enzyme activity (EA) and enzyme loading capacity (ELC) are 95.6%, 31997 U/g, 110 mg/g, respectively. Lastly, the operational stability, reusability, and storage stability of Mg2+-Fe3O4 @ β-CD-g-GA-PGA NPs were researched. Relative to free PGA, immobilized PGA has better operation stability and storage stability. After 11 repeated uses, the immobilized PGA still has 56% of the initial vitality, and the carrier recovery (Re) is 86.6%.
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Ficin extract has been immobilized on different 4% aminated-agarose beads. Using just ion exchange, immobilization yield was poor and expressed activity did not surpass 10% of the offered enzyme, ...with no significant effects on enzyme stability. The treatment with glutaraldehyde of this ionically exchanged enzyme produced an almost full enzyme inactivation. Using aminated supports activated with glutaraldehyde, immobilization was optimal at pH 7 (at pH 5 immobilization yield was 80%, while at pH 9, the immobilized enzyme became inactivated). At pH 7, full immobilization was accomplished maintaining 40% activity versus a small synthetic substrate and 30% versus casein. Ficin stabilization upon immobilization could be observed but it depended on the inactivation pH and the substrate employed, suggesting the complexity of the mechanism of inactivation of the immobilized enzyme. The maximum enzyme loading on the support was determined to be around 70 mg/g. The loading has no significant effect on the enzyme stability or enzyme activity using the synthetic substrate but it had a significant effect on the activity using casein; the biocatalysts activity greatly decreased using more than 30 mg/g, suggesting that the near presence of other immobilized enzyme molecules may generate some steric hindrances for the casein hydrolysis.
The effects of microplastic exposure on the non-specific immune responses and intestinal microflora remain unclear. In this study, juveniles of the Chinese mitten crab (Eriocheir sinensis) were ...exposed to different concentrations of microplastics (0, 0.04, 0.4, 4, and 40 mg/L) for 7, 14, and 21 days to explore their effects. Under microplastic-induced stress, the contents or activities of most immune-related factors haemocyanin (Hc), alkaline phosphatase (AKP), phenoloxidase (PO), lysozyme (LSZ), and acid phosphatase (ACP) decreased after an initial increase in the low-dose or short exposure times in the haemolymph and hepatopancreas. The trends in Hc and LSZ gene expression were consistent with the corresponding changes in enzyme activities. Moreover, the haemocyte expression of caspase and MyD88 in the groups with microplastic-induced stress was higher than that in the control group, whereas the expression levels in the hepatopancreas were first increased and then decreased. Furthermore, the relative abundance of Firmicutes and Bacteroidetes decreased following exposure to 40 mg/L microplastics, whereas that of Fusobacteria and Proteobacteria increased. These results indicate that microplastics affect immune enzyme activity and immune-related gene expression and change the diversity and composition of the intestinal microflora in E. sinensis.
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•The effect of microplastics on enzyme activity and gene expression were evaluated in crab•Microplastics provokes different levels of immune inhibition in the hemolymph and hepatopancreas E. sinensis•Microplastic exposure altered the intestinal microbiota profile of E. sinensis
In the current study, we conducted a field experiment using the test plant, Brassica chinesis L. (pak choi), to investigate the effect of sugarcane bagasse-derived biochar on the bioavailability of ...cadmium (Cd), copper (Cu) and lead (Pb), and the health of soil microbiota in a contaminated soil. Biochar application significantly (P < 0.05) increased pak choi yield. Bioavailability of heavy metals to plant shoots and roots decreased with increasing biochar application rates (at 0, 1.5, 2.25 and 3.0 t ha−1). Sequential extraction of the biochar-treated and -untreated soil revealed that exchangeable Cd reduced whereas organically-bound fraction increased with increasing biochar rate. The labile fractions of Cu and Pb decreased, but the residual fraction increased in biochar-treated soils compared to the control. Urease, catalase and invertase activities, and the populations of bacteria and actinomycetes were significantly enhanced, whereas fungi population declined in biochar-treated soils. This study highlights that sugarcane bagasse biochar has the potential to support the remediation of soils contaminated with heavy metals, and as such can improve the yield and quality of agricultural crops.
•Sugarcane bagasse biochar amendment reduced availability of Cd, Cu and Pb in soils.•Heavy metals were less labile in the biochar-treated soils.•Biochar amendment induced an increase in soil enzyme and microbial activity.•Edible part of pak choi was safer for human consumption after biochar amendment.
The clinical application of oncology therapy is hampered by high glutathione concentrations, hypoxia, and inefficient activation of cell death mechanisms in cancer cells. In this study, Fe and Mo ...bimetallic sulfide nanomaterial (FeS2@MoS2) based on metal‐organic framework structure is rationally prepared with peroxidase (POD)‐, catalase (CAT)‐, superoxide dismutase (SOD)‐like activities and glutathione depletion ability, which can confer versatility for treating tumors and mending wounds. In the lesion area, FeS2@MoS2 with SOD‐like activity can facilitate the transformation of superoxide anions (O2−) to hydrogen peroxide (H2O2), and then the resulting H2O2 serves as a substrate for the Fenton reaction with FMS to produce highly toxic hydroxyl radicals (∙OH). Simultaneously, FeS2@MoS2 has an ability to deplete glutathione (GSH) and catalyze the decomposition of nicotinamide adenine dinucleotide phosphate (NADPH) to curb the regeneration of GSH from the source. Thus it can realize effective tumor elimination through synergistic apoptosis‐ferroptosis strategy. Based on the alteration of the H2O2 system, free radical production, glutathione depletion and the alleviation of hypoxia in the tumor microenvironment, FeS2@MoS2 NPS can not only significantly inhibit tumors in vivo and in vitro, but also inhibit multidrug‐resistant bacteria and hasten wound healing. It may open the door to the development of cascade nanoplatforms for effective tumor treatment and overcoming wound infection.
The bimetallic sulfide nano‐materials (FeS2@MoS2) based on a metal‐organic framework structure are prepared by calcination method. FeS2@MoS2 is multifunctional for tumor therapy and bacterial wound repair. It can eliminate tumor effectively through a synergistic apoptosis‐ferroxide apoptosis strategy, and bind to amino groups on the surface of drug‐resistant bacteria to effectively inhibit bacteria and accelerate wound healing.
Microplastics have become ubiquitous in soils on a global scale, which may elicit profound deleterious impacts on soil health. However, contradictory case studies have prevented a clear understanding ...of how microplastics hierarchically impact soil carbon cycling. A meta-analysis was performed to systematically elucidate the effects of microplastics on carbon cycling, particularly in terms of CO2 and CH4 emissions. Upon exposure to microplastics, the overall soil CO2 emissions increased by 54.3%, as were the soil organic carbon (22.6%), dissolved organic carbon (13.3%), and microbial biomass carbon (5.5%). Sufficient carbon substrates supported the replication of functional genes that governed the decomposition of carbon (4.0%; e.g., abfA, sga, and manB, etc.), whereas the gene copies for carbon fixation (accA and pccA) were negligibly affected. Moreover, soil enzymatic (e.g., dehydrogenase, fluorescein diacetate hydrolase, and chitinase) activities were also enhanced. Meanwhile, the CO2 emissions were positively correlated with the gene copy numbers of carbon-decomposing microorganisms. Similarly, the soil CH4 emissions increased by 9.7%, where the increment of methanogen (41.1%; mcrA) was slightly higher than that of methanotrophs (37.9%; pmoA, mmoX and mxaF). Moreover, CH4 emissions were positively correlated with methanogen gene copies, and the increment of CH4 emissions was more pronounced in paddy soil (11.3%) than in upland soil. Microplastics with smaller dimensions, round shapes, higher concentrations, and biodegradability leaded to higher soil CO2 and CH4 emissions. Meanwhile, the effect sizes of CO2 and CH4 emissions decreased over time. These findings revealed that soil carbon cycling was expedited following microplastics exposure, which should be factored into future environmental risk assessments.
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•Soils with microplastics increased CO2 (54.3%) and CH4 (9.7%) emissions.•Microorganism abundance in carbon degradation was increased upon microplastics.•Soil with biodegradable microplastics emitted more CO2 and CH4.•Smaller sizes, higher dosages and round microplastics induced more CO2 and CH4.
Soil extracellular enzyme stoichiometry (EES), the ratio of extracellular enzyme activities (EEAs) related to the acquisition of nutrients such as carbon (C), nitrogen (N) and phosphorus (P), ...reflects the demand for resources by microorganisms. However, how grassland restoration shifts microbial nutrient limitation as indicated by soil EES remains unclear. Here, we evaluated microbial nutrient limitation by studying soil EES across a chronosequence of grassland restoration sites. The ratio of the natural logarithm of C-, N-, and P-acquiring enzymes in our studied system ranged from 1:1.47:1.05 to 1:0.82:1.38, and the average was 1:1.08:1.28, deviating from the global ratio of 1:1:1 and indicating that microorganisms were co-limited by N and P. Enzyme N:P ratio increased and vector angles decreased with time since restoration, suggesting that the restored grassland shifted from P-limitation (angles>45°) to N-limitation (angles<45°), and N limitation gradually exacerbated over time. Strong relationships between microbial biomass C:N:P ratios and soil EES suggest that soil EES was dependent on microbial resource availability. We also found that the variation in soil EES was better explained by biotic than by abiotic factors, and the total variation explained increased with time since restoration, indicating that biotic control over soil EES increased over time as the environmental conditions such as soil moisture availability and nutrients improved for microorganisms. Overall, this study highlights the utility of the ecoenzymatic stoichiometry approach in assessing relationships in microbial resource ecology, and such insights provide guidance in developing restoration strategies such as the need for nutrient management in grassland ecosystems.
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•Soil C-, N-, P-acquiring enzymes gradually increased with grassland restoration.•The natural logarithm of soil C-, N-, P-acquiring enzyme ratio was 1:1.08:1.28.•Soil microorganisms shift from P- to N-limitation with grassland restoration.•The variation in soil EES was better accounted by biotic factors than by abiotic factors.
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•FM increased microbial C metabolism while very small effects on P metabolism.•Increased microbial C metabolism ascribe to increased soil moisture content.•N fertilization increased ...the microbial demand for P (microbial P limitation).•Changes in nutrient stoichiometry and N availability led to P limitation increase.•Microbial P limitation strongly inhibited nitrification and denitrification potential.
Variations in soil microbial metabolism currently represent one of the greatest areas of uncertainty with regard to soil nutrient cycles and the control of terrestrial carbon (C) and nitrogen (N) loss and are poorly understood in agricultural ecosystems with intensive farming practices. In this study, extracellular enzymatic stoichiometry models and quantitative PCR techniques were used to examine microbial metabolic limitation and its relationship with N-cycling gene expression in semi-arid agricultural ecosystems considering four N fertilization levels (N 0, N 100, N 250, and N 400 kg N ha−1) and two agronomic strategies (film mulching and no mulching). Film mulching increased microbial C limitation (reflecting microbial C metabolism size; 0.189 of the total effects), while very small effects on microbial phosphorus (P) limitation were observed (-0.007 of the total effects). N fertilization increased the microbial demand for P (microbial P limitation; 0.504 of the total effects). Increased microbial C metabolism was mainly attributed to increased soil moisture content after film mulching, which enhanced microbial decomposition of organic C (high C-acquiring enzyme activities). Changes in nutrient stoichiometry and the increase in N availability due to N fertilization were largely responsible for increased microbial P limitation. Furthermore, microbial P limitation negatively affected the abundance of AOA amoA, AOB amoA (involved in nitrification), nirK, nirS, nosZ (involved in denitrification) genes, strongly inhibiting nitrification and denitrification potential (-0.743 and -0.761 of the total effects, respectively). The present results suggest that agricultural ecosystems with film mulching are conducive to organic residue decomposition, while appropriate P limitation under N fertilization could reduce the loss of N due to nitrification and denitrification in soil. This study highlights the importance of elemental stoichiometry-driven microbial metabolic variation in understanding soil nutrient cycles and optimizing agricultural practices.
Phenolic compounds (PCs) are diverse in nature and undergo complex migration and transformations in the environment, making it challenging to use techniques such as chromatography and other ...traditional methods to determine the concentration of PCs by separation, individual monitoring and subsequent addition. To address this issue, a facile and on-site strategy was developed to measure the concentration of PCs using a novel nanozyme with polyphenol oxidase-like activity. First, the nanozyme was designed by coordinating the asymmetric ligand nicotinic acid with copper to mimic the structure of mononuclear and trinuclear copper clusters of natural laccases. Subsequently, by introducing 2-mercaptonicotinic acid to regulate the valence state of copper, the composite nanozyme CuNA10S was obtained with significantly enhanced activity. Interestingly, CuNA10S was shown to have a broad substrate spectrum capable of catalyzing common PCs. Building upon the superior performance of this nanozyme, a method was developed to determine the concentration of PCs. To enable rapid on-site sensing, we designed and prepared CuNA10S-based test strips and developed a tailored smartphone sensing platform. Using paper strip sensors combined with a smartphone sensing platform with RGB streamlined the sensing process, facilitating rapid on-site analysis of PCs within a range of 0–100 μM. Our method offers a solution for the quick screening of phenolic wastewater at contaminated sites, allowing sensitive and quick monitoring of PCs without the need for standard samples. This significantly simplifies the monitoring procedure compared to more cumbersome large-scale instrumental methods.
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•A novel nanozyme mimicking the laccase structure.•A facile and on-site sensing strategy for phenolic compounds.•The test paper strip-based smartphone-assisted sensing platform.
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