Urease Activity Research Articles

Enhancing soil quality in intensive rice cultivation through short-term growth of green manure and its incorporation combined with rice husk or its ash: a laboratory incubation study

ABSTRACT A novel approach, i.e. mung bean was grown in paddy soil for 1 month as a pre-rice crop, which is a short but a feasible period applicable to the current intensive rice monoculture cropping system in the Vietnamese Mekong Delta. This study aimed to assess how short-term growth of green manure and its incorporation combined with rice husk or its ash impact the soil quality of sandy loam soil and silty clay soil. Four treatments, viz. soil without mung bean (control), soil plus mung bean incorporation, soil plus mung bean and rice husk of 10 Mg ha−1, and soil plus mung bean and rice husk ash of 5 Mg ha−1, were established. Different soil parameters were determined to evaluate their initial effects after incubating for 60 days. In both soils, the incorporation of mung bean significantly increased β-glucosidase, acid phosphatase, and urease activities, as well as C mineralization compared with control. Soil labile C was increased by 15–50% by incorporation of mung bean, irrespective of the application of rice husk or its ash, compared to that in control. The highest total C and available N were found in mung bean combined with rice husk followed by mung bean with rice husk ash, only mung bean, and control. Sandy loam soil with a lower exchangeable K level showed significant improvements in the exchangeable K content with rice husk and its ash amendments. Therefore, these practices, short-term green manure planting, could offer benefits to farmers for enhancing soil quality such as enzyme activities in the intensive paddy cultivation.

Enhancing Soil Health and Tea Plant Quality Through Integrated Organic and Chemical Fertilization Strategies

As the global demand for high-quality tea increases, adopting sustainable agricultural practices is crucial to maintaining environmental health and improving crop productivity. Employing organic fertilizers has the potential to boost agricultural output and improve soil health, as well as curb the spread of pests and diseases. The purpose of this survey was to determine the impact of a range of organic fertilizer mixtures on both tea plants and rhizosphere soil characteristics in tea plantations. This study investigated the response of Jin Guanyin tea (Camellia sinensis L.) plants to various organic fertilizer ratios: 2/3 chemical fertilizer + 1/3 organic fertilizer (JTC), 1/2 chemical fertilizer + 1/2 organic fertilizer (JHOC), 1/3 chemical fertilizer + 2/3 organic fertilizer (JTO), and organic fertilizer only (JOF), with chemical fertilizer alone (JCF) as the control. The experiment was conducted in Xingcun Town, Wuyishan, Fujian Province, China, on 13 October 2021. Key metrics measured included tea plant growth indicators, soil physicochemical properties, enzyme activities, and microbial functional diversity. Results show that JTC and JTO produce the largest leaf area and bud weight, significantly surpassing those in JCF. JCF demonstrated the longest new tip length and highest bud density, while JHOC achieved the highest chlorophyll content, significantly exceeding JCF. Soil analysis revealed that total nitrogen, available nitrogen, organic matter, and pH were highest in JOF, significantly overtaking JCF. Conversely, total phosphorus, available potassium, and available phosphorus levels were highest in JCF. JHOC also had the highest total potassium content compared to JCF. Soil enzyme activity assessments showed that polyphenol oxidase and urease activities peaked in JTC, significantly exceeding those in JCF. JHOC exhibited the highest acid phosphatase activity, while JTO exhibited the highest protease activity. Catalase activity was highest in JOF, both significantly surpassing JCF. Microbial functional diversity analysis indicated that combined organic fertilization improved soil microorganisms’ utilization of carbon sources, significantly enhancing the Shannon diversity index and evenness. Key carbon sources identified included α-cyclodextrin, D-galacturonic acid, and 4-hydroxy benzoic acid. Overall, JHOC emerged as the optimal fertilization strategy, yielding superior growth indicators, enhanced soil physicochemical properties, increased enzyme activity, and improved microbial functional diversity compared to JCF. This study has important value for guiding the rational application of fertilizers in tea gardens, improving the soil environment of tea gardens, enhancing the quality of tea leaves, and achieving sustainable tea production.

Effects of Microplastic Pollution on Microbial Activity and Carbon Metabolism Function in Soil

Clarifying the ecological effects of microplastics （MPs） in soil is a frontier problem in environmental science research. A 60-d microcosmic culture experiment was conducted using soil with three relative abundances （2%, 5%, and 10%, MPs/soil）, of traditional MPs polystyrene （PS） and biodegradable MPs polylactic acid （PLA）. Additionally, the changes in microbial activity and carbon metabolism function in the soil after cultivation were analyzed. The results showed that： After cultivation with MPs, the soil pH decreased and the content of dissolved organic carbon （DOC） in the soil significantly increased. The addition of MPs significantly reduced the activities of catalase and polyphenol oxidase in the soil and the reduction degree was related to the concentration of MPs. However, the addition of PLA significantly enhanced the activity of soil urease, while PS had no significant effect on urease activity. The addition of MPs led to a decrease in the carbon metabolism ability of soil microbial communities. The carbon metabolism ability of soil microorganisms cultured with PS was higher than that of those cultured with PLA. The inhibitory effect of both on soil carbon metabolism was positively correlated with their concentration. The concentrations of PS （10%） and PLA （10%） had the strongest inhibitory effect on soil microbial carbon metabolism ability, with a decrease of 63.91% and 82.27%, respectively. PLA had a greater impact on soil microbial activity and carbon metabolism than that of PS because PLA in soil degraded easily to produce harmful dissolved organic matter and smaller plastic particles. The research results provide a theoretical basis for clarifying the ecological effects of MPs in soil and basic data for future development of standards related to soil MPs pollution.

Physicochemical property and microbial community characteristics of the casing soil for cultivating Oudemansiella raphanipes

BackgroundCasing soil is critical for the cultivation process of Oudemansiella raphanipes and promotes the formation of mushroom fruiting bodies. Therefore, reliable casing soil indicators are crucial for obtaining high yields of high-quality mushrooms.MethodsIn this study, soil enzyme activity, physicochemical properties, and microorganisms at five cultivation stages [namely casing (A1), mycelial (A2), primordial (A3), fruiting (A4), and harvesting (A5)] of O. raphanipes cultivation were evaluated in casing soils.ResultsThe results indicated that sucrase and catalase activities were significantly increased with increasing cultivation time (p < 0.01), and the activities peaked [16.67 and 0.25 g/(g·h), respectively] at A4. Urease activity peaked [1.56 g/(g·h)] at A1, and it decreased gradually (p < 0.01). Polyphenol oxidase activity was significantly higher at A2 [0.95 g/(g·h)] than at the other stages and was significantly lower at A1 [0.06 g/(g·h)]. Soil pH peaked at A1 (8.20) and decreased gradually (p = 0.003). Soil total organic carbon content increased significantly with increasing cultivation time (p < 0.001) and was the highest at A5 (8.40 g/kg). The available phosphorus at A1 (0.40 g/kg) was significantly higher than those at the other stages (p = 0.004), and the available nitrogen at A1 (0.28 g/kg) and A3 (0.26 g/kg) was significantly higher than those at the other stages (p < 0.001). The number and diversity of bacteria and fungi in soil increased gradually, and nine bacterial and four fungal genera were identified.ConclusionThis study offers soil characteristic and microbial community data for O. raphanipes casing soil at different cultivation stages, which could facilitate sustainable cultivation of O. raphanipes and reduction of live contaminants.

English

Paddy residues burning is a common practice in the sub-continent to manage paddy waste,which results in deterioration of air quality in the surrounding areas and causes smog issue. In situ decomposition could be a viable option to manage this problem. About thirteen (13) cellulose degrading bacterial strains were selected and further screened based on various enzymatic activities. Finally, two strains (GW7 and HA 121) with highest enzymatic potential were selected for optimization of factors to enhance cellulase production. The selected bacterial strain GW7 was found positive for urease, protease, catalase, phosphates and cellulase activity. While HA121 strain was positive for urease, protease, phosphatase and cellulase enzymes. The strains GW7 and HA121 exhibited maximum cellulose activity of 23 U mL-1 and 19 U mL-1, respectively, at optimized conditions. The optimal conditions for GW7 were temperature 35°C, pH 8, 1.5% glucose and 0.5% urea concentration. However, for HA121 the highest cellulase activity was attained when 1% glucose and 0.5% urea as co-inducers were used at a temperature of 35 °C and pH 8 where cellulase enzyme production was found to be 19 U mL-1. The optimization of cellulolytic bacterial cultures for enhanced cellulase production has established its potential utilization for field application.

Curious Effects of Overlooked Aspects on Urease Activity

Curious Effects of Overlooked Aspects on Urease Activity

Mechanism of antimony oxidation and adsorption using immobilized Klebsiella aerogenes HC10 in soil

Klebsiella aerogenes HC10 is one of the few strains isolated from contaminated soil that efficiently oxidizes Sb. However, the sensitivity of microorganisms to environmental conditions limits Sb-oxidizing bacteria applications in soil remediation. Immobilizing Sb-oxidizing bacteria is a promising strategy to improve colonization rates and microorganism inefficiencies and to strengthen bioremediation in Sb-contaminated soil. This study evaluated the feasibility of an immobilization approach to enhance Sb oxidation and the remediation performance of strain HC10 in soil. The results indicated that a mixed matrix of polyvinyl alcohol and sodium alginate as fixed carriers provided a porous microstructural environment conducive to HC10 colonization and proliferation. Sb(III) concentration was reduced by 9.8 mg/L. The total Sb decreased by 3.8 mg/L by immobilized HC10 after 7 d. Key metabolites involved in Sb oxidation and adsorption were significantly upregulated. In soil, immobilized HC10 removed 48.68 % and 61.74 % of water-extractable and citric acid-extractable Sb(III), respectively. Some well-crystallized (hydr)oxide Sb fractions binding to the mineral surface were transformed into the mineral lattice form, creating an inner-sphere complex that effectively immobilized Sb. Immobilized HC10 enhanced hydrogen peroxidase, urease, and sucrase activities related to soil antioxidants and nutrient cycling. Immobilized HC10 promoted the proliferation of indigenous bacteria, which emerged as the dominant bacterial community with the potential for Sb oxidation. The ars operon genes associated with Sb resistance and transport were significantly expressed in HC10 treatments, providing a crucial basis for colonization in the soil. These results highlight the potential of immobilized Sb-oxidizing bacteria for enhanced bioremediation of Sb-contaminated soil.

Improving non-uniform gravelly sand using microbially induced carbonate precipitation: An outdoor cubic-meter scale trial by engineering contractors

Soil improvement using microbially induced carbonate precipitation (MICP) remains largely confined to the laboratory, with only a very small number of large-scale experiments having been completed under field conditions and none by engineering contractors. This study presents a cubic-meter scale improvement of heterogeneous natural sand collected from a local quarry, with a wide variation in grain size, via MICP. The MICP trial was conducted by engineering contractors in a cubic test cell under variable temperatures ranging from 5 °C to 19 °C. The upscaling of cultivation of Sporosarcina pasteurii (600 L for each treatment cycle) under non-sterile conditions, as performed by engineering contractors, achieved an optical density (OD600) of 0.89 and a specific urease activity of 2.5 mM urea/min/OD600. Post-MICP-treated sands were subjected to a series of coring, block sampling and laboratory tests. The block sampling process indicated that the majority of sand was effectively cemented, with a small region near a side wall forming a less well-cemented zone, likely induced by less effective fluid delivery in this region. The unconfined compressive strengths of three cores (diameter: 10 cm, length: 22 cm) were 3.6, 4.4, and 7.6 MPa. Consolidated-drained triaxial tests on sub-sampled cores also demonstrated rock-like material behaviour, with a peak friction angle of 43.6° and peak cohesion of 0.64 MPa, and ultimate state frictional angles of 42.0° and ultimate cohesion of 0.12 MPa. The increased shear parameters of the bio-cemented samples (relative to the untreated samples) have many implications for mitigation of geotechnical hazards such as soil liquefaction. The study marks a step forward industrial implementation of MICP for soil improvement by engineering contractors without prior knowledge of MICP.

Plant litter crust enhances nitrogen accumulation by regulating microbial diversity and urease activity in semi-arid sandy soils

Plant litter plays a crucial role in regulating soil nitrogen (N) cycling in dryland ecosystems. However, the mechanisms by which plant litter crust drives microbial community composition to influence N levels in sandy soils remain unclear. In this study, we examined the effects of litter crust on sandy soil microhabitat characteristics (temperature, moisture, and porosity), microbial diversity and composition, urease activity, and soil N variables (total-N, nitrate-N, and ammonium-N) across different stages of litter crust development (including early-, mid-, and post-term) in a field setting. We found that litter crust promotes bacterial and fungal alpha diversity in sandy soils, leading to a shift in bacterial community composition from oligotrophs (i.e., Actinobacteria) to copiotrophs (i.e., Proteobacteria and Bacteroidetes), and a shift in fungal community composition dominance from Ascomycota to Basidiomycota. Litter crust enhances the complexity and stability of bacterial and fungal co-occurrence networks in sandy soils, especially in early- and mid-term stages of crust development. Additionally, litter crust increases nitrification (aerobic ammonia oxidation) and decreases denitrification (nitrate reduction) in these soils. Notably, the increase in soil moisture and urease activity, along with the decrease in soil temperature due to litter crust, effectively promotes N accumulation in sandy soils. Our results demonstrate that N levels during the litter crust period are mainly influenced by a combination of bacterial beta diversity and fungal alpha diversity at the 0–5 cm depth, and bacterial alpha diversity along with soil properties (i.e., soil variables and urease activity) at the 5–10 cm depth. Overall, our results reveal that litter crust contributes to N accumulation in sandy soils by regulating bacterial and fungal community composition and diversity, as well as by buffering soil temperature and soil moisture, and enhancing urease activity. These findings provide new insights into the critical role of soil microbes in maintaining N functions during litter crust development in semi-arid sandy ecosystems.

The CRISPR/Cas system-mediated function of Hg2+ on urease activity for colorimetric detection of the tumor biomarker in clinical samples

Detecting tumor biomarkers in blood samples is essential in cancer diagnosis and prognosis. This study proposes a CRISPR/Cas system-mediated colorimetric assay to detect the tumor biomarker in human serum samples. It involves using the tumor biomarker as a switch of the CRISPR/Cas system to modulate the function of Hg2+, which is a typical urease inhibitor. The detection of carcinoembryonic antigen (CEA) is demonstrated as an example. The CEA aptamer is used to activate the CRISPR/Cas system, allowing for the cleavage of a single-stranded DNA (ssDNA) rich in thymine (T) nucleotides, thereby causing the inhibition of the urease activity by Hg2+. However, in the presence of CEA, the CRISPR/Cas system cannot be activated due to the specific binding of CEA to its aptamer, which leads to the capture of Hg2+ owing to the formation of a DNA hairpin structure with T-Hg2+-T coordination bonds. Thus, the urease activity is remained. Since the enzymatic hydrolysis of urea by urease increases the pH of the urea solution containing phenol red and changes the solution from yellow to pink, CEA can be detected with the assistance of the colorimetric assay. This method shows high sensitivity and selectivity for CEA with a detection limit of 0.028 ng/mL. In addition, serum samples from patients with normal and abnormal levels are tested to verify the validity of the proposed method for practical applications. Overall, this study provides a simple, fast, and stable colorimetric assay to detect the tumor biomarker in human serum and has great potential for early cancer screening and prognostic determination.

Streptomyces sp. 30702 composite chitosan alleviates continuous cropping obstacles in Chinese yam by improving rhizospheric soil microbial environment: A field study in Hainan

Yam is a vital medicinal plant, yet its cultivation faces increasing challenges, particularly due to pathogenic diseases linked to continuous cropping obstacles. This study examines the effects of Streptomyces sp. 30702 and Chitosan on anthracnose and soil microbial communities across four treatment groups: CK (control), SP (Streptomyces sp. 30702), CTS (chitosan), and SC (combined Streptomyces sp. 30702 and Chitosan) within a continuous yam cropping system. The yam was watered every 20 days with 0.25 g plant−1 of chitosan and 4.2 × 10⁵ CFU plant−1 of Streptomyces sp. 30702. Notably, the SC treatment significantly reduced the disease index by 41.31 %, cut root-knot nematode populations by 95.40 %, and boosted yield by 205.45 % compared to CK (P > 0.05). SC treatment also increased soil levels of available nitrogen, phosphorus, potassium, and urease activity. High-throughput sequencing highlighted the dominance of three bacterial phyla (Acidobacteriota, Proteobacteria, and Actinobacteriota) and three fungal phyla (Ascomycota, Basidiomycota, and unidentified Fungi) at harvest. At the bacterial genus level, Bacillus showed a significant increase in SC compared to CK, while LEfSe analysis identified five marker microorganisms in CTS (including Flavobacterium) and four in SC at the fungal genus level. Importantly, SC management reduced the relative abundance of Colletotrichum, the primary cause of anthracnose, by 42.27 % compared to CK. In the Hainan yam continuous cropping system, four Amplicon Sequence Variants (ASVs) were identified as bacterial connectors, two as module hubs, and two as fungal connectors, underscoring their roles in decomposition and environmental adaptability. The results of the Redundancy Analysis (RDA) indicate that available phosphorus in the soil significantly affects the composition of bacterial and fungal communities, with the greatest influence. Additionally, available potassium, available nitrogen, and root-knot nematodes significantly influence the bacterial community, while available nitrogen and root-knot nematodes significantly affect the fungal community (P < 0.05). Overall, the combination of Streptomyces sp. 30702 and chitosan proved to be an effective bio-agent duo, regulating soil microbial communities, reducing anthracnose, and providing a theoretical basis for addressing continuous cropping challenges in yam cultivation.

Exploration of urease-aided calcium carbonate mineralization by enzyme analyses of Neobacillus mesonae strain NS-6.

Urease containing nickel cofactor is crucial for urea-hydrolytic induced calcium carbonate (CaCO3) precipitation (UICP). However, limited information exists regarding the influence of amino acid residues interacting with nickel ions in its structure on induced CaCO3 mineralization. Herein, RT-qPCR was used to demonstrate that the addition of NiCl2 dramatically upregulated the expression of urease structural gene ureC that was correlated with nickel binding in Neobacillus mesonae strain NS-6. Homology modeling and molecular docking were employed to construct the three-dimensional structure of urease and seek the key residues involved in nickel binding process, and virtual mutation technology was adopted to inform three key residues coordinated with nickel ions and urea, His249, His275, and Asp363. Four metrics, including root mean square deviation values for mutations of those key residues in urease-urea complexes severally and wild-type, were calculated by molecular dynamics simulations when they were mutated into alanine, respectively. Subsequently, the mutations of H249A, H275A, and D363A were characterized using western blotting to reveal a decrease in the relative expression and activity of urease, along with a corresponding reduction in CaCO3 precipitation. Ultimately, the mutations also exhibited that they had lower substrate affinity and catalytic efficiency for urea through enzymatic properties analysis. The findings suggested that those residues played a pivotal role in UICP of strain NS-6, which would expand the theoretical basis for modulating urease activity.IMPORTANCEUrease-producing bacterium is of great importance in diverse application fields, such as environmental remediation, due to its key driving characteristics in catalyzing urea hydrolysis via urea-hydrolytic induced CaCO3 precipitation (UICP). As essential cofactors of urease, nickel ions play a crucial role in regulating urease catalysis and maintaining structural stability. Numerous investigations have emphasized the impact of nickel ions on urease activity in recent years, to our best knowledge, only a few literatures have studied the molecular-level regulation of nickel-ligand residues. This study focused on the highly urease-producing bacterial Neobacillus mesonae NS-6 to explore the effects of specific nickel-ligand residues on the urease-aided CaCO3 mineralization process using molecular simulation predictions and targeted mutation experiments. The aim was to provide a molecular-level understanding of the interactive effects between urea and critical residues associated with the urease active center, as well as propose an effective modification strategy to enhance the application of UICP in future environmental areas.

Microplastic effects on soil nitrogen cycling enzymes: A global meta-analysis of environmental and edaphic factors

Microplastic accumulation in soil ecosystems poses significant environmental concerns, potentially impacting nitrogen cycling processes and ecosystem health. This meta-analysis of 147 studies (1138 data points) assessed the impact of microplastics (MPs) on soil nitrogen-acquisition enzymes. We found that MPs exposure significantly increased soil urease (UE) and leucine aminopeptidase activities by 7.6 % and 8.0 %, respectively, while N-acetyl-β-D-glucosaminidase activity was not significantly affected. Biodegradable MPs showed more pronounced effects compared to conventional MPs. Enzyme activities were influenced by MPs properties (e.g., polymer type, size, concentration), experimental conditions (e.g., field or laboratory setting, temperature, nitrogen fertilization), and soil properties (e.g., clay content, pH, organic carbon, total nitrogen). For instance, acidic soils enhanced UE activity, while neutral soils reduced it. These findings emphasize the complex interactions between MPs and soil ecosystems, highlighting the need for context-specific environmental management strategies and policy-making approaches to mitigate the impacts of MPs pollution on soil health.

Improving the Microenvironmental of Spring Soybean Culture and Increasing the Yield by Optimization of Water and Nitrogen

Optimizing water and nitrogen management is an effective measure to reduce nitrogen fertilizer loss and environmental pollution risks. This study aims to quantify the impacts of different water and nitrogen management strategies on the soil microenvironment and yield of spring soybeans in southern Xinjiang. In this study, two irrigation quotas were established: W1—36 mm (low water) and W2—45 mm (high water). Three nitrogen application gradients were established: low nitrogen (150 kg·hm−2, N1), medium nitrogen (225 kg·hm−2, N2), and high nitrogen (300 k kg·hm−2, N3). The analysis focused on soil physicochemical properties, enzyme activities, microbial community diversity, soybean yield, and soybean quality changes. The results indicate that the activities of nitrate reductase and urease, as well as total nitrogen content, increased with higher irrigation and nitrogen application rates. The W2N3 treatment significantly increased 0.15 to 4.39, 0.18 to 1.04, and 0.31 to 1.73 times. (p &lt; 0.05). Alkaline protease and sucrase activities increased with higher irrigation amounts, while their response to nitrogen application exhibited an initial increase followed by a decrease. The W2N2 treatment significantly increased by 0.10 to 0.34 and 0.07 to 1.46 times (p &lt; 0.05). Irrigation significantly affected the soil bacterial community structure, while the coupling effects of water and nitrogen notably influenced soil bacterial abundance (p &lt; 0.05). Increases in irrigation and nitrogen application enhanced bacterial diversity and species abundance. Partial least squares path analysis indicated that water–nitrogen coupling directly influenced the soil microenvironment and indirectly produced positive effects on soybean yield and quality. An irrigation quota of 4500 m3 hm−2 and a nitrogen application rate of 300 kg·hm−2 can ensure soybean yield while enhancing soil microbial abundance. The findings provide insights into the response mechanisms of soil microbial communities in spring soybeans to water–nitrogen management, clarify the relationship between soil microenvironments and the yield and quality of spring soybeans, and identify optimal irrigation and fertilization strategies for high quality and yield. This research offers a theoretical basis and technical support for soybean cultivation in southern Xinjiang.

The Effects of Heavy Metals on Enzyme Activity and Microbial Biomass of the Soil Around the Waste Disposal Site (Case Study of Saravan - Iran)

ABSTRACT Municipal solid waste is considered an environmental threat in Iran. The study was performed on soil near the Saravan dumpsite and measured the concentrations of 8 metals (Zn, Cu, As, Hg, Pb, Cr, Cd, and Ni) in soil, by inductively coupled plasma mass spectrometry. The average content of As, Cu, Cr, Pb, Zn, Hg, Ni, and Cd in soil were 10.48, 20.22, 19.07, 24.95, 28.83, 0.13, 19.91, and 0.1 mg/kg, respectively. The mobility factors based on water-soluble and exchangeable fractions were As (8.85%), Zn (4.19%), Pb (1.85%), Cu (1.60%), and Cr (0.02%), and not detectable for Hg, Ni, and Cd. Evaluation of metals contamination by pollution index, integrated pollution index, and Nemerowʼs pollution index for each metal showed that PI for all metals except Hg was in the range of low to moderate, and for Hg, 50% in high pollution grade; the average of the IPI (1.21), indicated a moderate pollution condition; the mean value of the PINemerow (1.20), which was in slight pollution grade. The correlations between total concentrations of metals, and bioavailable fractions with microbial biomass carbon, basal respiration, microbial quotient, metabolic quotient, urease, and alkaline phosphatase activities were moderate (r = 0.4-0.6). The activity of urease was from 37.79 to 1414.31 µg N gˉ1 dm.2 hˉ1 and alkaline phosphatase from 34.66 to 698.78 µg nitrophenyl gˉ1 dm. hˉ1. Due to the rainy climate and the continuous leaching of the surface soil, we suggested performing waste separation and the treatment of leachate produced before flowing downstream.

Impact of Chinese milk vetch incorporation with reduced chemical fertilizers on the soil properties, rice growth and cadmium uptake in Cd-contaminated paddy fields

Green manure returning can improve soil fertility and crop production, and immobilize heavy metals in the soil. However, limited information is available on the effects of green manure replacing chemical fertilizers on soil properties and crop growth. In this study, we investigated the effects of Chinese milk vetch incorporation with reduced chemical fertilizers on soil properties, rice agronomic traits and cadmium (Cd) accumulation by field experiments, and four treatments were conducted: chemical fertilizer alone (CF), milk vetch alone (MV), milk vetch plus 80% chemical fertilizers (MVCF80), and milk vetch plus 50% chemical fertilizers (MVCF50). The results showed that all milk vetch treatments decreased soil pH and Eh, and increased the SOM, DOC contents and the activities of catalase and urease. The soil DTPA-Cd contents decreased by 20.41%, 18.20%, and 21.22%, and the Cd accumulation in rice root, stem, leaf, and grain decreased by 21.13%-37.62%, 20.74%-39.61%, and 21.91%-43.56% under MV, MVCF80, and MVCF50 treatments, respectively. Additionally, the MVCF80 treatment showed a better rice agronomic traits and grain yield than others. These data revealed the great potential of milk vetch incorporation with chemical fertilizer reduction in decreasing Cd accumulation in rice plants and improving rice quality and yield of Cd-contaminated paddy fields.

Effect of Biochars Derived from Different Agricultural Wastes Under Different Pyrolyzing Temperatures on Microbial Properties of a Loam-Clay Soil During Plant Growing Season

ABSTRACT A two-season experiment to identify an efficient strategy for the optimized soil microbial activity using biochar from four agricultural residues subjected to two different pyrolyzing temperatures (300°C and 500°C) was conducted in greenhouse conditions. The biochar types were identified according to the final pyrolyzing temperature as vineyard pruning biochar-300°C (VB300), vineyard pruning biochar-500°C (VB500), tomato biochar-300°C (TB300), tomato biochar-500°C (TB500), clove biochar-300°C (CB300), clove biochar-500°C (CB500), banana biochar-300°C (BB300) and banana biochar-500°C (BB500). The experimental design consisted of a randomized complete block design with five replications and 9 treatments including the control with a total of 45 pots. Soil samples were taken after biochar applications at two-week intervals (0, 2nd, 4th, 6th and 8th week) during the growth period of lettuce (Lactuca sativa var. Crispa) and analyzed for chemical (pH and EC) and biological parameters (urease, alkaline phosphatase, β-glucosidase, dehydrogenase, nitrification, denitrification activities and bacterial count). Biochar applications were found to have an impact on enzyme activities in various degrees. Selected biochar treatments increased pH, EC, urease, alkaline phosphatase, β-glucosidase and nitrification activities but not the bacterial count in the first growing period. However, no significant difference was found among treatments in the second growing period (except β-glucosidase). Overall evaluation of the data suggested that, under the experimental conditions, feedstock type, rather than pyrolyzing temperature, appeared to be more influential on the biological parameters monitored and banana biochar was found to be the most effective one in the short term.

The Role of Sodium Alginate Hydrogel in Maintaining Soil Homeostasis Exposed to Sulcotrione

Herbicides are the most widely used agrochemicals in crop protection, which has led to serious environmental pollution around the world, including soil ecosystems. It is important to look for new solutions that lead to an improvement in soil quality, even if only through the use of hydrogels. The aim of this study was therefore to determine the effect of sodium alginate on the microbiological and biochemical properties of sulcotrione-treated soil. It was found that both the herbicide and the sodium alginate had a significant effect on the soil environment. An amount of 10 g kg−1 of sodium alginate was applied to the soil, while sulcotrione was applied to the soil in the following amounts: 0.00 (C), 0.200 (R), 0.999 (5R), and 9.999 mg kg−1 (50R). Sulcotrione stimulated the activity of dehydrogenases, catalase, arylsulfatase, and β-glucosidase and inhibited the activities of alkaline phosphatase, acid phosphatase, and urease as well as the proliferation of organotrophic bacteria, actinobacteria, and fungi. This caused an increase in the colony development index (CD) of organotrophic bacteria and fungi and decreased the colony development index value of actinobacteria. It also increased the value of the ecophysiological diversity index (EP) of fungi. The addition of sodium alginate to the soil increased the numbers of organotrophic bacteria, actinobacteria, and fungi as well as the activities of dehydrogenases, catalase, urease, alkaline phosphatase, and arylsulfatase. The hydrogel had different effects on β-glucosidase activity. Acid phosphatase showed a significant decrease in activity after the addition of sodium alginate to the soil. Under the influence of sodium alginate, there was an increase in the index of colony development of actinobacteria and fungi, while there were decreases in organotrophic bacteria and the index of ecophysiological diversity of actinobacteria and fungi. The proliferation of microorganisms and the enzymatic activity of the soil changed over time both in soil enriched with sodium alginate and without its addition. This study may be useful for evaluating the effects of sulcotrione on the microbiological and biochemical properties of soil and the effectiveness of sodium alginate in improving the quality of soil exposed to sulcotrione.

Biodegradable Acid‐Responsive Nanocarrier for Enhanced Antibiotic Therapy Against Drug‐Resistant Helicobacter Pylori via Urease Inhibition

AbstractMetal ion‐based inhibition of urease activity is a promising strategy for treating Helicobacter pylori (H. pylori) infections. However, the challenges of safe delivery and reducing cytotoxicity persist. In this study, an innovative nanocarrier capable of acid‐responsive release of Ag+ and antibiotics is developed, with complete degradation after treatment. Mesoporous organosilica nanoparticle (MON) is encapsulated with hyaluronic acid (HA) to prevent drug leakage and further coated with bacterial outer membrane vesicle (OMV) from Escherichia coli Nissle 1917, creating a nanocarrier with cell‐protective capabilities. Ag+ and antibiotic clarithromycin (CLR) are incorporated into the nanocarrier to form CLR‐Ag+@MON@HA@OMV (CAMO), designed for the targeted treatment of gastric H. pylori infection. The HA encapsulation ensures acid‐responsive release of CLR and Ag+ in the stomach, preventing premature release at non‐inflammatory sites. There is a potential for Ag⁺ in CAMO to replace Ni2⁺ at the active site of urease, enhancing the bactericidal effect of CLR through urease inhibition. Furthermore, the OMV provides additional cytoprotection, mitigating cell damage and inflammation response induced by the H. pylori infection. This study introduces a safe and effective nanocarrier that eradicates H. pylori and alleviates gastric inflammation.

The effect of three urease inhibitors on H. pylori viability, urease activity and urease gene expression.

Treatment of Helicobacter pylori (H. pylori) infections is challenged by antibiotic resistance. The urease enzyme contributes to H. pylori colonization in the gastric acidic environment by producing a neutral microenvironment. We hypothesized that urease inhibition could affect H. pylori viability. This work aimed to assess the effects of acetohydroxamic acid (AHA), ebselen and baicalin on urease activity, bacterial viability and urease genes expression in H. pylori isolates. Forty-nine H. pylori clinical isolates were collected. Urease activity was assessed using the phenol red method. The urease inhibition assay assessed inhibitors' effects on urease activity. Flow cytometry assessed the effect of inhibitors on bacterial viability. Real time PCR was used to compare urease genes expression levels following urease inhibition. Urease activity levels differed between isolates. Acetohydroxamic acid inhibited urease activity at a concentration of 2.5 mM. Although baicalin inhibited urease activity at lower concentrations, major effects were seen at 8 mM. Ebselen's major inhibition was demonstrated at 0.06 mM. Baicalin (8 mM) significantly reduced ATP production compared to untreated isolates. Baicalin, ebselen and acetohydroxamic acid significantly reduced H. pylori viability. Increased urease genes expression was detected after exposure to all urease inhibitors. In conclusion, higher concentrations of baicalin were needed to inhibit urease activity, compared to acetohydroxamic acid and ebselen. Baicalin, ebselen and acetohydroxamic acid reduced H. pylori viability. Therefore, these inhibitors should be further investigated as alternative treatments for H. pylori infection.