Soil enzymes, as indicators of microbial metabolism, play an important role in nutrient biogeochemistry at the ecosystem level. In this study, we present information from a comprehensive analysis of ...the latitudinal variations in, and stoichiometric relationships between, soil β-glucosidase (BG), N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP) in nine forest ecosystems along the North-South Transect in eastern China. The results showed that soil BG and NAG activities were higher in temperate forests than in subtropical and tropical forests. Soil AP activities were the opposite, which indicates that microbial nutrient demand in tropical forests was limited by the nutrient phosphorus (P). Soil BG and NAG activities were significantly and negatively correlated with mean annual temperature (MAT), mean annual precipitation (MAP), the soil carbon (C):P and soil nitrogen (N):P ratios, but not with the soil C:N ratio. Soil NAG and AP activities were inversely correlated with soil pH, and soil AP activity increased as soil pH decreased. The latitudinal variations in the C:N, C:P, and N:P acquisition ratios represented by ln(BG):ln(LAP + NAG):ln(AP) activities across ecosystems were significantly and negatively related to MAP and MAT. The C:P and N:P acquisition ratios were positively related to soil pH but negatively related to the soil C:P and N:P ratios. The C:N and C:P acquisition ratios were also negatively correlated with leaf C:N, C:P, and N:P ratios. This study provides useful information about environmental controls on enzyme stoichiometry, and also highlights the stoichiometric and energy limitations on the metabolism of soil microbes.
•Soil BG and NAG activities increased as latitude increased.•Soil acid phosphatase was greatest in tropical and subtropical climate zones.•Latitudinal variation mechanism of soil EEA stoichiometry along the NSTEC.•Variations in the soil EEA stoichiometry were influenced by climate and soil pH.•Soil EEA stoichiometry was correlated with nutrients in plant leaves and soils.
Soils always receive microplastics (MPs) from plastic mulching, compost, and sewage irrigation, but the effects of MPs on soil environment remain largely unexplored. The objectives of this study were ...to investigate the effects of three MPs (membranous polyethylene (PE), fibrous polypropylene (PP), and microsphere PP) on enzyme activities and microbial community structure in one loamy and sandy soil. The concentration of microsphere PP (2 mg/g) was one-tenth of those of the other two MPs (20 mg/g). The results showed that the effects of three MPs on urease, dehydrogenase, and alkaline phosphatase activities followed the order: fibrous PP > membranous PE > microsphere PP, membranous PE > microsphere PP > fibrous PP and fibrous PP > microsphere PP > membranous PE, respectively. Results from high-throughput sequencing of 16S rRNA revealed that the membranous PE and fibrous PP raised the alpha diversities of the soil microbiota, whereas the diversity indexes of microbiota on MPs surfaces were significantly lower than those in the amended soils. MPs significantly altered the microbial community structure, especially for the enrichment of Acidobacteria and Bacteroidetes, the depletion of Deinococcus-Thermus and Chloroflexi. Aeromicrobium, Streptomyces, Mycobacterium, Janibacter, Nocardia, Arthrobacter were prone to inhabit on the MPs surfaces. PRACTITIONER POINTS: Three microplastics had different effects on soil enzyme activities. Fibrous PP had a more persistent effect on microbial activity. Membranous PE and fibrous PP raised the alpha diversities of soil microbiota. The effects of membranous PE and fibrous PP on microbial communities were similar. Distinct microbial communities were enriched on the surfaces of microplastics.
•Biochar was used as a carrier for immobilizing Cd-Cu resistant strain NT-2.•Strain NT-2 quickly colonized and secreted EPS on the surface of biochar.•Application of 5% NT-2 loaded biochar decreased ...the bioavailability of Cd and Cu.•Soil enzyme activity markedly recovered in the NT-2 loaded biochar treatment.•NT-2 loaded biochar greatly improved soil microbial community profile.
The application of biochar in the remediation of heavy metal contaminated soil has received increasing global attention during the past decade. Although there has been some review work on the mechanism of heavy metals stabilization by biochar, the effects and mechanisms of interaction between biochar and functional microbes such as heavy metal tolerant, adsorption and transformation microbial strains remains unclear. In this paper, maize biochar and a heavy metal-tolerant strain Pseudomonas sp. NT-2 were selected to investigate the dynamic effects and potential mechanisms of biochar and bacteria loaded biochar on the stabilization of Cd and Cu mixed contaminated soil by a 75-day pot experiment. The results showed that, compared to the single biochar amendment, the application of biochar inoculated with NT-2 strain at the rate of 5% significantly increased the soil pH at the initial stage of incubation, and followed by a slight decline to a neutral-alkaline range during the reaction. The addition of NT-2 loaded biochar could also significantly increase the proportion of residual fraction of Cd and Cu, thus reduce the proportion of exchangeable and carbonate bound species in the soil, which lead to the decreasing of plant and human bioavailability of the metal in the soil indicated by DTPA and simulated human gastric solution extraction (UBM), respectively. Finally, the application of bacterial loaded biochar also markedly enhanced soil urease and catalase activities during the later stage of the incubation, and improved soil microbial community at the end of incubation, which indicates a recovery of soil function after the metal stabilization. The research results may provide some new insights into the development of functional materials and technologies for the green and sustainable remediation of heavy metal contaminated soil by the combination of biochar and functional microorganisms.
•Manure application significantly increased crop yield by 7.6%.•Manure application in acidic soils, warm and humid climates can benefit crop yield.•Long-term manure application increased soil ...sustainable productivity.
The intensive use of mineral fertilizer may have negative effects on plant growth and the soil environment, but the application of manure could alleviate these problems. However, the effects of manure application on crop yield and soil properties in different climates, soil conditions, and management practices should be investigated before we could conclude that it is universally practical. We performed a meta-analysis of 774 comparisons from 141 published studies and found that manure application increased yield by an average of 7.6% compared to mineral fertilizer. The effects of manure application were more pronounced in acidic soils, warm and/or humid climates, and longer experimental periods. Manure application also increased soil pH (3.3%), water-stable aggregation (28.8%), soil organic carbon (17.7%), total (15.5%) and available nitrogen (16.0%), available phosphorus (66.2%), available potassium (19.1%), the activities of urease (23.5%), sucrase (18.3%), and catalase (16.1%), and the abundances of bacteria (60.0%), fungi (27.7%), and actinomyces (38.0%). Manure application decreased soil bulk density (−3.9%). Increases in the nutrient pool and decompositional capacity of the soil may explain the positive effects of manure application on yield. Our results indicate that long-term manure application may improve sustainable soil productivity and crop yield in China.
Farming practices that integrate plastic film mulching and nitrogen (N) fertilization have been extensively used to enhance crop productivity. However, the interactive effects of mulching and N ...application on soil microbial properties and crop yields have received little attention. A 2‐year field experiment was carried out in the Loess Plateau to investigate the independent and combined effects of plastic mulch and N application rate on the soil microbial population, enzymatic activity and grain yield. From 2016 to 2017, two mulching patterns (i.e., plastic mulching and no mulching) were exposed to five different N application rates (0 (N0), 80 (N80), 160 (N160), 200 (N200) and 240 (N240) kg N ha−1). N application significantly affected the soil microbial community composition, as suggested by significant increases in soil total bacteria, cellulose‐decomposing bacteria and the bacterial‐to‐fungal ratio with N rates. In contrast, the mulching pattern significantly affected soil extracellular enzyme production. Furthermore, there were significant effects of mulching, N application and their interaction on grain yield. The highest grain yield (11,728 kg N ha−1 in 2016 and 12,350 kg N ha−1 in 2017) in both growing seasons was consistently obtained under plastic mulching with a N level of 200 kg N ha−1. Our study showed that plastic mulching significantly affected extracellular enzyme production, and N fertilizer application significantly affected the composition of the soil microbial community.
Highlights
Independent and coupled effects of mulching and N application on soil biological properties and grain performance were explored.
N application significantly influenced soil microbial community composition.
Mulching pattern rather than N application independently and significantly affected soil extracellular enzyme production
The combined application of plastic mulching with 200 kg N ha−1 should be seem as an optimum crop production pattern in this area.
As a less O2‐dependent photodynamic therapy (PDT), type I PDT is an effective approach to overcome the hypoxia‐induced low efficiency against solid tumors. However, the commonly used metal‐involved ...agents suffer from the long‐term biosafety concern. Herein, a metal‐free type I photosensitizer, N‐doped carbon dots/mesoporous silica nanoparticles (NCDs/MSN, ≈40 nm) nanohybrid with peroxidase (POD)‐like activity for synergistic PDT and enzyme‐activity treatment, is developed on gram scale via a facile one‐pot strategy through mixing carbon source and silica precursor with the assistance of template. Benefiting from the narrow bandgap (1.92 eV) and good charge separation capacity of NCDs/MSN, upon 640 nm light irradiation, the excited electrons in the conduction band can effectively generate O2•− by reduction of dissolved O2 via a one‐electron transfer process even under hypoxic conditions, inducing apoptosis of tumor cells. Moreover, the photoinduced O2•− can partially transform into more toxic •OH through a two‐electron reduction. Moreover, the POD‐like activity of NCDs/MSN can catalyze the endogenous H2O2 to •OH in the tumor microenvironment, further synergistically ablating 4T1 tumor cells. Therefore, a mass production way to synthesize a novel metal‐free type I photosensitizer with enzyme‐mimic activity for synergistic treatment of hypoxic tumors is provided, which exhibits promising clinical translation prospects.
A metal‐free mesoporous N‐doped carbon dots/mesoporous silica nanoparticles (NCDs/MSN) type I photosensitizer for synergistic photodynamic therapy and peroxidase‐like activity treatment of hypoxic tumors is developed via a facile one‐pot strategy. Upon 640 nm light irradiation, massive O2•– and •OH are generated through an electron transfer mechanism even in hypoxic conditions. Moreover, NCDs/MSN can catalyze overpressed H2O2 to •OH in tumor microenvironment due to its enzyme‐mimic activity, enhancing the anti‐tumor outcome.
The proceeding study aimed to isolate glyphosate-degrading bacteria from soil and determine optimal degradation conditions through single-factor experiments and response surface methodology. The ...detoxifying efficacy of the isolate on glyphosate was assessed using earthworm model. The results indicate that Pseudomonas putida HE exhibited the highest glyphosate degradation rate. Optimal conditions for glyphosate degradation were observed at an inoculation percentage of approximately 5%, a pH of 7, and a temperature of 30 °C. Glyphosate induced notable neurotoxicity and reproductive toxicity in earthworms, evidenced by reduced activity of the neurotoxicity-associated enzyme AChE. Additionally, an increase in the activities of catalase, superoxide dismutase, and lactate dehydrogenase was observed. H&E staining revealed structural disruptions in the earthworm clitellum, with notable atrophy in the structure of spermathecae. Furthermore, glyphosate activation of earthworm immune systems led to increased expression of immune-related genes, specifically coelomic cytolytic factor and lysozyme. Notably, the introduction of strain HE mitigated the glyphosate toxicity to the earthworms mentioned above. P. putida HE was able to increase soil enzyme activities that were reduced due to glyphosate. The isolate P. putida HE, emerged as an effective and cost-efficient remedy for glyphosate degradation and toxicity reduction in natural settings, showcasing potential applications in real ecological settings.
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•A novel glyphosate-degrading P. putida strain HE was isolated and characterized.•The optimal conditions for glyphosate degradation by P. putida HE was studied.•Glyphosate was shown to cause neurological, reproductive, and immunological toxicity in earthworms.•P. putida HE alleviates glyphosate-induced toxicity in earthworms.•Glyphosate and P. putida HE affects soil enzyme activities.
High-throughput profiling of key enzyme activities of carbon, nitrogen, and antioxidant metabolism is emerging as a valuable approach to integrate cell physiological phenotyping into a holistic ...functional phenomics approach. However, the analyses of the large datasets generated by this method represent a bottleneck, often keeping researchers from exploiting the full potential of their studies. We address these limitations through the exemplary application of a set of data evaluation and visualisation tools within a case study. This includes the introduction of multivariate statistical analyses which can easily be implemented in similar studies, allowing researchers to extract more valuable information to identify enzymatic biosignatures. Through a literature meta-analysis, we demonstrate how enzyme activity profiling has already provided functional information on the mechanisms regulating plant development and response mechanisms to abiotic stress and pathogen attack. The high robustness of the distinct enzymatic biosignatures observed during developmental processes and under stress conditions underpins the enormous potential of enzyme activity profiling for future applications both in basic and applied research. Enzyme activity profiling will complement molecular -omics approaches to contribute to the mechanistic understanding required to narrow the genotype-to-phenotype knowledge gap and to identify predictive biomarkers for plant breeding to develop climate-resilient crops.
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•CO2 and weak magnetic field promoted TN removal efficiency as high as 96.2 ± 1.6 %.•N2O emission flux decreased by 20.5% with 35 mT weak magnetic field.•Fe3O4 precipitate decreased ...and low-density metastable FeO(OH)/ FeCO3 increased.•Abundance of denitrifier unclassified Rhodocyclaceae and Denitratisoma increased.
Combining iron-carbon micro-electrolysis and autotrophic denitrification is promising for nitrate removal from wastewater. In this study, four continuous reactors were constructed using CO2 and weak magnetic field (WMF) to address challenges like iron passivation and pH stability. In the reactors with CO2 + WMF (10 and 35 mT), the increase in total nitrogen removal efficiency was significantly higher (96.2 ± 1.6 % and 94.1 ± 2.7 %, respectively) than that of the control (51.6 ± 2.7 %), and Fe3O4 converted to low-density FeO(OH) and FeCO3, preventing passivation film formation. The WMF application decreased the N2O emissions flux by 8.7 % and 20.5 %, respectively. With CO2 + WMF, the relative enzyme activity and abundance of denitrifying bacteria, especially unclassified_Rhodocyclaceae and Denitratisoma, increased. Thus, this study demonstrates that CO2 and WMF optimize the nitrate removal process, significantly enhancing removal efficiency, reducing greenhouse gas emissions, and improving process stability.
Ohmic heating (OH), an emerging food processing technology employed in the food processing industry, raises potential food safety concerns due to the recovery of sublethally injured pathogens such as ...Staphylococcus aureus (S. aureus). In the present study, sensitivity to various stress conditions and the changes in cellular-related factors of OH-injured S. aureus during repair were investigated. The results indicated that liquid media differences (nutrient broth (NB), phosphate-buffered saline (PBS), milk, and cucumber juice) affected the recovery process of injured cells. Nutrient enrichment determines the bacterial repair rate, and the rates of repair for these media were milk > NB > cucumber juice > PBS. The sensitivity of injured cells to various stressors, including different acids, temperature, nisin, simulated gastric fluid, and bile salt, increased during the injury phase and subsequently diminished upon repair. Additionally, the intracellular ATP content, enzyme activities (Na+/K+-ATPase, Ca2+/Mg2+-ATPase, and T-ATPase) and ion concentrations (Mg2+, K+, and Ca2+) gradually increased during repair. After 5 h of repair, the intracellular substances content of cell's was significantly higher than that of the injured bacteria without repair, while some indicators (e.g., Na+/K+-ATPase, K+, and Ca2+) were not restored to the untreated level. The results of this study indicated that OH-injured S. aureus exhibited strengthened resistance post-recovery, potentially due to the restoration of cellular structures. These findings have implications for optimizing food storage conditions and advancing OH processes in the food industry.
•The nutrient richness of culture medium influences the repair of OH-injured S. aureus.•The sensitivity of the injured cells increased and restored during repair.•The intracellular enzyme activity and ion concentrations, and cell membrane integrity were repaired during repair.
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