Urease Enzyme Activity Research Articles

Revealing the Enhancement and Degradation Mechanisms Affecting the Performance of Carbonate Precipitation in EICP Process

Given that acid-rich rainfall can cause serious damage to heritage buildings in NW China and subsequently accelerate their aging problem, countermeasures to protect their integrity and also to preserve the continuity of Chinese culture are in pressing need. Enzyme-induced carbonate precipitation (EICP) that modifies the mechanical properties of the soil through enhancing the interparticle bonds by the precipitated crystals and the formation of other carbonate minerals is under a spotlight in recent years. EICP is considered as an alternative to the microbial-induced carbonate precipitation (MICP) because cultivating soil microbes are considered to be challenging in field applications. This study conducts a series of test tube experiments to reproduce the ordinary EICP process, and the produced carbonate precipitation is compared with that of the modified EICP process subjected to the effect of higher MgCl2, NH4Cl, and CaCl2 concentrations, respectively. The modified EICP, subjected to the effect of higher MgCl2 concentrations, performs the best with the highest carbonate precipitation. The enhancement mechanism of carbonate precipitation is well interpreted through elevating the activity of urease enzyme by introducing the magnesium ions. Furthermore, the degradation of carbonate precipitation presents when subjected to the effect of higher NH4Cl concentration. The decreasing activity of urease enzyme and the reverse EICP process play a leading role in degrading the carbonate precipitation. Moreover, when subjected to the effect of higher CaCl2 concentrations, the slower rate of urea hydrolysis and the decreasing activity of urease enzyme are primarily responsible for forming the “hijacking” phenomenon of carbonate precipitation. The findings of this study explore the potential use of the EICP technology for the protection of heritage buildings in NW China.

Microalgae biomass as a renewable biostimulant: meat processing industry effluent treatment, soil health improvement, and plant growth

ABSTRACT Microalgae biomass contributes to effluent bioremediation. It is a concentrated source of nutrients and organic carbon, making it a potential alternative as a soil biostimulant. In this context, this study aimed to evaluate the soil application of microalgae biomass produced from the meat processing industry effluent treatment. The biomass was applied dry and as a mixture to demonstrate its potential to increase plant production and soil metabolic functions, analyzed short-term. Doses of 0.25%, 0.5%, 1%, and 2% biomass were applied in soils from (i) Horizon A: taken at a depth between 0 and 10 cm and; (ii) Horizon B: taken at a depth between 20 and 40 cm. Corn growth (Zea Mays L.), basal soil respiration, microbial biomass carbon, total organic carbon, β-glucosidase, acid phosphatase, arylsulfatase, and urease enzymatic activity were evaluated in each sample. It is concluded that applying 2% microalgae biomass led to higher basal soil respiration, microbial biomass carbon, and β-glucosidase, acid phosphatase, arylsulfatase enzymatic activity in both soils. On the other hand, boron may have contributed to urease activity reduction in Soil A. Although 2% biomass led to higher soils characteristics, that dose did not promote higher plant growth. Hence, considering that plant growth must be in line with changes in soil characteristics, the result that provided the higher plant shoot dry matter mass was by applying 0.55% biomass in both soils. Therefore, the application of microalgae biomass produced from a meat processing industry effluent treatment promoted a biologically active soil and boosted plant growth.

Responses of the Soil Microbial Community to Salinity Stress in Maize Fields.

Simple SummarySoil microorganisms are the core of maintaining soil ecological functions. Recognition of microbial community diversity in saline soil contributes to nutrient management and crop production. Meanwhile, microbial activity is easily affected by changes in soil properties. This study addressed how the composition and diversity of bacterial and fungal communities changed under different saline conditions to identify the sensitivity of bacteria or fungi to salinity. The primary objective was to evaluate the relationship between soil’s microbial community diversity and soil’s physicochemical factors, and to explore the vital microbial predictors in salinized soil. The results showed that Firmicutes and Bacteroidetes are pivotal in salinized soil, and this finding can provide guidance for the demand for plant rhizosphere growth-promoting bacteria as a bioindicator in saline soil.To investigate the diversity and structure of soil bacterial and fungal communities in saline soils, soil samples with three increasing salinity levels (S1, S2 and S3) were collected from a maize field in Yanqi, Xinjiang Province, China. The results showed that the K+, Na+, Ca2+ and Mg2+ values in the bulk soil were higher than those in the rhizosphere soil, with significant differences in S2 and S3 (p < 0.05). The enzyme activities of alkaline phosphatase (ALP), invertase, urease and catalase (CAT) were lower in the bulk soil than those in the rhizosphere. Principal coordinate analysis (PCoA) demonstrated that the soil microbial community structure exhibited significant differences between different salinized soils (p < 0.001). Data implied that the fungi were more susceptible to salinity stress than the bacteria based on the Shannon and Chao1 indexes. Mantel tests identified Ca2+, available phosphorus (AP), saturated electrical conductivity (ECe) and available kalium (AK) as the dominant environmental factors correlated with bacterial community structures (p < 0.001); and AP, urease, Ca2+ and ECe as the dominant factors correlated with fungal community structures (p < 0.001). The relative abundances of Firmicutes and Bacteroidetes showed positive correlations with the salinity gradient. Our findings regarding the bacteria having positive correlations with the level of salinization might be a useful biological indicator of microorganisms in saline soils.

Isolation and Evaluation of Rhizosphere Actinomycetes With Potential Application for Biocontrolling Fusarium Wilt of Banana Caused by Fusarium oxysporum f. sp. cubense Tropical Race 4.

Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense tropical race 4 (TR4) is globally one of the most destructive soil-borne fungal diseases. Biological control using environmental microorganisms is considered as an alternative and sustainable strategy. Actinomycetes have the potential to explore biocontrol agents due to their production of diverse metabolites. The isolation and identification of high-efficiency and broad-spectrum antagonistic actinomycetes are the key for the application of biocontrol agents. In the present study, 60 actinomycetes were obtained from the rhizosphere soil of Machilus pingii in the primitive ecological natural reserve of Hainan province, China. Seventeen isolates and their extracts exhibited significant antifungal activity against F. oxysporum TR4. Particularly, strain BITDG-11 with the strongest inhibition ability had a broad-spectrum antifungal activity. The assay of its physiological and biochemical profiles showed that strain BITDG-11 had the ability to produce IAA and siderophores and had a positive response to gelatin liquefaction and nitrate reduction. Enzyme activities of chitinase, β-1,3-glucanase, lipase, and urease were also detected. Average nucleotide identity calculated by comparison with the standard strain genome of Streptomyces albospinus JCM3399 was 86.55% below the novel species threshold, suggesting that the strain could be a novel species. In addition, Streptomyces BITDG-11 obviously reduced the disease index of banana plantlets and promoted plant growth at 45 days post inoculation. The higher and lasting expression levels of defense genes and activities of antioxidant enzymes were induced in the roots of banana. Genome sequencing revealed that the Streptomyces BITDG-11 chromosome contained large numbers of conserved biosynthesis gene clusters encoding terpenes, non-ribosomal peptides, polyketides, siderophores, and ectoines. Fifteen bioactive secondary metabolites were further identified from Streptomyces BITDG-11 extract by gas chromatography–mass spectrometry. Dibutyl phthalate demonstrating a strong antifungal activity was the major compound with the highest peak area. Hence, Streptomyces sp. BITDG-11 has a great potential to become an essential constituent of modern agricultural practice as biofertilizers and biocontrol agents.

A Study on the Hydrolysis of Urea Contained in Wastewater and Continuous Recovery of Ammonia by an Enzymatic Membrane Reactor

1. Background: Urea is the main product of the nitrogenous breakdown of protein metabolism in mammals. In this study, process intensification for enzymatic hydrolysis of urea by urease enzyme (jack bean urease) was examined in a membrane reactor. 2. Methods: Batch and continuous enzymatic hydrolysis reactions were performed at different substrate concentrations to determine the digestibility and affinity of the substrate with that of the enzyme. The hydrolysate samples were obtained by an optimized continuous enzyme membrane reactor (EMR) coupled with an ultra-filtration membrane (250 kDa). Feed concentration varied from 100 to 500 mg/L. Laboratory experiments were conducted at room temperature (20 ± 1 °C), with a flow rate of 20 mL/min, urease concentration of 0.067 g/L, ionic strength (I = 0, 0.01, 0.05), and ammonium nitrogen addition of (0, 100 mg/L, 200 mg/L, 500 mg/L). Moreover, the effect of ionic strength, ammonium nitrogen concentration, feed concentration, and enzyme concentration on urea hydrolysis was examined. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX) analysis were used to identify the physicochemical properties as well as the elemental composition of the Ultra-Filtration membrane used in this study. 3. Results: The study revealed that higher ionic strength and higher concentrations of NH4SO2 and ammonium nitrogen (NH3-N) inhibithydrolysis of urea by reducing the urease enzyme activity in the system over time. 4. Conclusions: Herein, a sustainable alternative for the conversion of urea to ammonia by utilizing urease in an EMR was demonstrated.

Effects of Different Biochar Amendments on Soil Enzyme Activities and Carbondioxide Emission

ABSTRACT Biochar production from organic waste offers an important alternative for waste management, also improves soil properties (bio-physico-chemical) and reduces heavy metal pollution risk caused by the excessive use of chemical fertilizers applied directly to the soils. Biochar is also proposed as an important management strategy to mitigate the negative impacts of greenhouse gases, which are among the most important causes of global climate change. This study aimed to investigate the effects of biochars produced from six different plant wastes on soil enzyme activity, CO2–C emission, total nitrogen (Nt), and nitrate (NO3–N) concentrations. Almond shell (AS), tobacco waste (TW), pomegranate peel (PP), cotton waste (CW), orange peel (OP), and wheat straw (WS) biochars were applied to the soil at the rates of 0.5, 1.0, and 1.5%, and the biochar amended soils were incubated in the laboratory environment (25 ± 2) for 37 weeks. The highest CO2 ̶ C emission was recorded in OP biochar treatment, while the lowest emission was measured in PP treatment, indicating that OP biochar addition tended to decrease C mineralization in the soil. The addition of AS biochar significantly increased the dehydrogenase and urease enzyme activities, while urease activity did not show a significant increase. The results can be attributed to the differences in composition and properties (C: N ratio, pH) of the biochars applied as well as the nature of the feedstocks used in biochar production. Biochar applications increased the Nt and NO3–N concentrations of the soils, and the highest increase was obtained in the WS treatment. The results of the study revealed that PP biochar can be recommended to reduce CO2–C emission from soils, AS biochar has a significant effect on urease and dehydrogenase enzyme activities, and the effect of WS biochar on Nt and NO3–N concentrations of soils were higher than the other five biochar types.

Enzymatic Activity of Sod-Podzolic Soil under Sosnowsky’s Hogweed

The activity of soil phosphatase, urease and invertase enzymes in sod-podzolic soil under the influence of Sosnowsky’s hogweed in the spring has been studied. In soil samples under the mono-community of Sosnowsky’s hogweed, high activity of the phosphatase and urease enzymes has been noted; the indicator of invertase activity is characterized as very weak or absent.

Gibberellic acid and urease inhibitor optimize nitrogen uptake and yield of maize at varying nitrogen levels under changing climate.

Worldwide, nitrogen (N) deficiency is the main yield limiting factor owing to its losses via leaching and volatilization. Urease inhibitors slow down urea hydrolysis in soil by inhibiting urease enzyme activities whereas gibberellic acid is growth regulator. That is why, we evaluated the role of urease inhibitor [N-(n-butyl)thiophosphorictriamide (NBPT)] and gibberellic acid (GA3) in improving nitrogen uptake and yield of maize under different N levels (120 and 150 kg ha-1) along with control. Both N levels alone and in combination with GA3 and NBPT significantly increased yield and yield components of maize over control. In addition, 150 kg N ha-1 + NBPT + GA3 produced highest biological, grain, and stover yields, 1000 grain weight, plant height, and N uptake exhibiting 33.15%, 56.46%, 27.56%, 19.56%, 23.24%, and 78% increase over 150 kg N ha-1, respectively. The sole use of gibberellic acid or NBPT with each level of N also improved the yield and yield components of maize compared to sole N application and control. Furthermore, application of 120 kg N ha-1 along with NBPT and GA3 performed at par to 150 kg N ha-1 + NBPT + GA3 but it was superior than sole applied 150 kg N ha-1 for all the studied traits. These results imply that application of GA3 and/or NBPT can reduce dependence on urea and improve the yield and N uptake in maize by slowing urea hydrolysis in calcareous soils and shall be practiced.

Investigating Helicobacter pylori-related pyloric hypomotility: functional, histological, and molecular alterations.

Multiple theories have been proposed describing the pathogenic mechanisms of Helicobacter pylori (H. pylori)-associated gastric motility disorders. We assessed ex vivo pyloric activity in H. pylori-infected rats, and tried to explore the associated ghrelin hormone alteration and pyloric fibrogenesis. In addition, miR-1 was assessed in pyloric tissue samples, being recently accused of having a role in smooth muscle dysfunction. Ninety adult male Wistar albino rats were assigned into nine groups: 1) control group, 2) sterile broth (vehicle group), 3) amoxicillin control, 4) omeperazole control, 5) clarithromycin control, 6) triple therapy control, 7) H. pylori- group, 8) H. pylori-clarithromycin group, and 9) H. pylori-triple therapy group. Urease enzyme activity was applied as an indicator of H. pylori infection. Ex vivo pyloric contractility was evaluated. Serum ghrelin was assessed, and histological tissue evaluation was performed. Besides, pyloric muscle miR-1 expression was measured. The immunological epithelial to mesenchymal transition (EMT) markers; transforming growth factor β (TGFβ), α-smooth muscle actin (α-SMA), and E-cadherin-3 were also evaluated. By H. pylori infection, a significant (P < 0.001) reduced pyloric contractility index was recorded. The miR-1 expression was decreased (P < 0.001) in the H. pylori-infected group, associated with reduced serum ghrelin, elevated TGFβ, and α-SMA levels and reduced E-cadherin levels. Decreased miR-1 and disturbed molecular pattern were improved by treatment. In conclusion, H. pylori infection was associated with reduced miR-1, epithelial to mesenchymal transition, and pyloric hypomotility. The miR-1 may be a target for further studies to assess its possible involvement in H. pylori-associated pyloric dysfunction, which might help in the management of human H. pylori manifestations and complications.NEW & NOTEWORTHY This work is investigating functional, histopathological, and molecular changes underlying Helicobacter pylori hypomotility and is correlating these with miR-1, whose disturbance is supposed to be involved in smooth muscle dysfunction and cell proliferation according to literature. Epithelial to mesenchymal transition and reduced ghrelin hormone may contribute to H. pylori infection-associated hypomotility. H. pylori infection was associated with reduced pyloric miR-1 expression. Targeting miR-1 could be valuable in the clinical management of pyloric hypofunction.

Inhibition of Urease, Elastase, and β-Glucuronidase Enzymatic Activity by Applying Aqueous Extracts of Opuntia oligacantha C.F. Först Acid Fruits: In Vitro Essay under Simulated Digestive Conditions

Non-communicable diseases such as gastric inflammatory diseases and the hepatic pathologies are mainly related to bad lifestyle habits such as recurrent consumption of non-steroidal anti-inflammatory drugs (NSAIDs), excessive intake of alcohol, tobacco, steroids (high doses), alkaline agents, strong acid foods, and high-fat food, and Helicobacter pylori infections, among others. The fruit of Opuntia oligacantha C.F. Först var. Ulapa (xoconostle) is currently being studied due its nutritional and functional properties. The objective of the present study was to evaluate gastroprotective, anti-inflammatory, and hepatoprotective activities of different parts of xoconostle fruit by establishing in vitro simulated gastrointestinal conditions. Four treatments were established to test aqueous extracts (pericarp (P), mesocarp (M), endocarp (E) and whole fruit (W)). The quantified bioactive compounds were the total phenols, flavonoids, tannins, and betalains. The enzymatic assays were: urease, elastase, and β-glucuronidase. Significant differences (p &lt; 0.05) of bioactive compounds content were measured in xoconostle extracts, the highest concentration was found in W (phenols 313 mg GAE/100 g, flavonoids 189 mg QE/100 g, tannins 71 mg CATE/100 g). The betalains content was higher in E; 17 mg/100 g significant differences were observed (p &lt; 0.05) in the enzymatic inhibitions test (urease, elastase and β-glucuronidase), where W presented the highest inhibition activity (86%, 79%, and 84%), respectively. Bioactive compounds after in vitro gastrointestinal tests were maintained above 60% enzymatic inhibition activity.

Bioinformatic analysis of metal transportomes from Mycobacteria Sp.

Mycobacterium is immovable induce aerobic, acid-fast gram-positive bacilli with high genomic content (59-66%). In the operon structure frequently establish for the genes of three molecular components: the ABC-binding protein, the membrane protein, and the substrate-binding protein, the rates of multidrug resistant and metal ions. The main objective of this study was to analyze the metal ions from five Mycobacterium species and to identify the metal transporters with “Genomic Island” associated features, in-silico analysis allowed identification of metal and drug transporters, phylogenetic analysis, genomic island path analysis, prediction of interacting metal ions, 3D structure, domain analysis and for the NiCoT metal transporter from Mycobacterium tuberculosis. These data are the first results of a big frame project that aims to accelerate the prioritizing of gene candidates that control element accumulation by taking advantage of high-throughput. The present in-silico study reveals the complete suite of NiCoT Metal Transporter in Mycobacterium tuberculosis H37Rv, which is involved in urease enzyme activity and biological function. The STRING analysis defines that the functional partners involved in transport of metal ions. While high expression yields of membrane proteins remain significant bottleneck for many proteins.

Effects of different fertilizers on some soil enzymes activity and chlorophyll contents of two cotton (G. hirsutum L.) varieties grown in a saline and non-saline soil

Cotton plant has two physiological development periods which are vegetative and generative periods. The activities of urease, dehydrogenase, glucosidase and alkaline phosphatase enzymes in the soil continue during the growth of plants. In this study, three different fertilizer sources (diammonium phosphate (DAP), vermicompost and manure) and two cotton varieties (Candia and Lima) were used in non-saline and saline soil conditions. The experimental layout was randomized plots with 3 replications. Total chlorophyll content of Candia and Lima cotton (Gossypium hirsutum L.) cultivars and urease, dehydrogenase, glucosidase and alkaline phosphate enzyme activities of the soil were determined. The chlorophyll content of cotton plants was significantly (p < 0.01) different in fertilizer treatments applied in non-saline and saline soils. The lowest chlorophyll value (17.83) in non-saline soil was obtained in the control, while the highest chlorophyll value (32.64) was recorded in the DAP fertilizer treatments. The lowest chlorophyll value (20.33) in saline soil was obtained from DAP fertilizer, while the highest chlorophyll value (24.11) was obtained in the vermicompost application. The fertilizer treatment significantly affected the urease activity in non-saline (p < 0.01) and saline (p < 0.05) soils. The highest mean urease enzyme activity in non-saline (102.74 µg N g−1 dry soil h−1) and saline (120.23 µg N g−1 dry soil h−1) soils was obtained in the DAP treatments. The highest mean dehydrogenase enzyme activity in non-saline (35.99 µg TPF g−1 dry soil 24 h−1) and saline (48.63 µg TPF g−1 dry soil 24 h−1) soils was obtained in cattle manure application. The difference between fertilizer applications was significant at p < 0.01 level in both soils.

Middle Bronze Age land use practices in the northwestern Alpine foreland – a multi-proxy study of colluvial deposits, archaeological features and peat bogs

Abstract. This paper aims to reconstruct Middle Bronze Age (MBA; 1600–1250 BCE) land use practices in the northwestern Alpine foreland (SW Germany, Hegau). We used a multi-proxy approach including the analysis of biogeochemical proxies from colluvial deposits and buried topsoils in the surroundings of the well-documented settlement site of Anselfingen and off-site pollen data from two peat bogs. This approach allowed for in-depth insights into the MBA subsistence economy and shows that the MBA in the northwestern Alpine foreland was a period of establishing settlements with sophisticated land management and land use practices. The reconstruction of phases of colluvial deposition was based on ages from optically stimulated luminescence (OSL) and radiocarbon (AMS14C) dating from multi-layered colluvial deposits and supports the local archaeological record with the first phase of major colluvial deposition occurring during the MBA followed by phases of colluvial deposition during the Iron Age, the Medieval period and modern times. The on-site deposition of charred archaeobotanical remains and animal bones from archaeological features, as well as polycyclic aromatic hydrocarbons (PAHs), charcoal spectra, phytoliths, soil microstructure, urease enzymatic activity, microbial biomass carbon (Cmic) and heavy metal contents from colluvial deposits, were used as proxies for on-site and near-site land use practices. The charcoal spectra indicate MBA forest management which favored the dominance of Quercus in the woodland vegetation in the surrounding area north of the settlement site. Increased levels of 5β stanols (up to 40 %) and the occurrence of pig bones (up to 14 %) support the presence of a forest pasture mainly used for pig farming. In the surrounding area south of the settlement, an arable field with a buried MBA plow horizon (2Apb) could be verified by soil micromorphological investigations and high concentrations of grass phytoliths from leaves and stems. Agricultural practices (e.g., plowing) focussed on five staple crops (Hordeum distichon/vulgare, Triticum dicoccum, Triticum monococcum, Triticum spelta, Triticum aestivum/turgidum), while the presence of stilted pantries as storage facilities and of heat stones indicate post-harvest processing of cereal crops and other agrarian products within the settlement. In the area surrounding the settlement, increased levels of urease activity, compared to microbial biomass carbon (up to 2.1 µg N µg Cmic-1), and input of herbivorous and omnivorous animal faeces indicate livestock husbandry on fallow land. The PAH suites and their spatial distribution support the use of fire for various purposes, e.g., for opening and maintaining the landscape, for domestic burning and for technical applications. The off-site palynological data support the observed change in on-site and near-site vegetation as well as the occurrence of related land use practices. During the Early and Middle Bronze Age, fire played a major role in shaping the landscape (peak of micro-charcoal during the MBA), and anthropogenic activities promoted Quercus-dominated forest ecosystems at the expense of natural beech forests. This indicates a broader regional human influence in the northwestern Alpine foreland at low- and mid-altitude inland sites during the Middle Bronze Age.

PH-Sensitive Oscillatory Motion of a Urease Motor on the Urea Aqueous Phase.

A self-propelled object coupled with an enzyme reaction between urease and urea was investigated at the air/aqueous interface. A plastic object that was fixed to a urease-immobilized filter paper was used as a self-propelled object, termed a urease motor, placed on an aqueous urea solution. The driving force of the urease motor is the difference in the surface tension around the object. Oscillatory motion or no motion was triggered depending on the initial pH of the urea solution. Both the frequency and maximum speed of the oscillatory motion varied depending on the initial pH of the water phase. The mechanisms underlying the oscillatory motion and no motion were discussed in relation to the bell-shaped enzyme activity of urease in the enzyme reaction and the surface tension around the urease motor.

Effect of Integrated Use of Organic Manures and Chemical Fertilizers under Soil Test Crop Response Approach on Soil Properties and Yield of Maize (Zea mays L.)

A field experiment was conducted at Crop Research Centre, G.B. Pant University of Agriculture and Technology, Pantnagar, during kharif 2019 to study the effect of integrated use of organic manures and chemical fertilizers under STCR approach on physico-chemical, biological properties of soil and yield of maize crop in a Mollisol. The experiment comprised of 9 treatments replicated thrice. The treatment details were Control (no fertilizers), RDF, STCR (inorganic mode), STCR INM mode, 75% STCR dose of N (inorganic mode) + Green manure, 50% STCR dose of N (inorganic mode) + Green Manure, 75% RDN + Green Manure, 50% RDN + Green Manure and FYM + Green Manure + Intercropping with urd. The lowest yield and soil properties were observed under control. The highest water holding capacity (63.20%), available N (183.98 kg ha-1), available P (28.94 kg ha-1), microbial biomass carbon (335.35 µg/g soil) and urease enzyme activity (30.06 µg urea/g soil/h) was observed under T4 (STCR INM mode). The highest organic carbon (0.99%), available K (200.85 kg ha-1) and dehydrogenase activity (223.60 µgTPF/gsoil/day) was observed under T5 (75% STCR dose of N (inorganic mode) + Green manure). The highest maize yield was observed under T4 (STCR INM mode). Therefore, the present investigation clearly reveals the significance of balanced and efficient utilization of resources under STCR approach on soil and crop productivity of maize crop.

Bio-Cementation in Construction Materials: A Review.

The rapid development of the construction sector has led to massive use of raw construction materials, which are at risk of exhaustion. The problem is aggravated by the high demand for cement as binding powder and the mass production of clay bricks for construction purposes. This scenario has led to high energy consumption and carbon emissions in their production. In this regard, bio-cementation is considered a green solution to building construction, because this technology is environmentally friendly and capable of reducing carbon emissions, thus slowing the global warming rate. Most of the previously published articles have focused on microbiologically induced calcium carbonate precipitation (MICP), with the mechanism of bio-cementation related to the occurrence of urea hydrolysis as a result of the urease enzymatic activity by the microbes that yielded ammonium and carbonate ions. These ions would then react with calcium ions under favorable conditions to precipitate calcium carbonate. MICP was investigated for crack repair and the surface treatment of various types of construction materials. Research on MICP for the production of binders in construction materials has become a recent trend in construction engineering. With the development of cutting edge MICP research, it is beneficial for this article to review the recent trend of MICP in construction engineering, so that a comprehensive understanding on microbial utilization for bio-cementation can be achieved.

In situ synthesis of micro-plastics embedded sewage-sludge co-pyrolyzed biochar: Implications for the remediation of Cr and Pb availability and enzymatic activities from the contaminated soil

Careful designing of biochar (BC) employing biological and industrial waste materials has gained much attention to improve soil health via reducing the bioavailability of heavy metals (HMs) in the contaminated-soil. Herein, a forty-day pot experiment was conducted to explore the influence of micro-plastic (MP) embedded sewage-sludge (SS). The effects of SS and MP dosage ratios (0–15%) on the physicochemical properties of the modified-biochars were also studied with slow-pyrolyzed (SBC-500 °C) and flash-pyrolyzed biochar (FSBC-700 °C). Our investigations found remarkable positive synergistic effects for the SBC-15% involving increased soil pH, CEC, high carbon contents, and alleviation in Cr and Pb leaching than control and FSBC-700 °C. Besides, SBC-15% containing high carbon functional groups can effectively mitigate the Cr and Pb availability stress by intensifying the adsorption or passivation in the amended-soil, thereby, significantly reducing the Cr and Pb EDTA-extractable contents. Chemical fractionation analyses further confirmed that SBC-15% addition was more helpful for Cr and Pb immobilization and ultimately reducing transfer-rate, bioconcentration-factor, and translocation-factor as compared to FSBC-15% and control due to its higher alkalinity, surface area/porosity, and available carbon functional groups. The maize biomass (root and shoot) increased by more than 50%, and the activities of soil enzymes such as urease, alkaline phosphatase, and glucosidase enzyme activities were also enhanced. This ecologically feasible strategy would pave an efficient way to make full use of the SS and MP for the biochar synthesis with excellent soil remediation performance.

Effects of Co-Applications of Biochar and Solid Digestate on Enzyme Activities and Heavy Metals Bioavailability in Cd-Polluted Greenhouse Soil

To deal with the problems of increasing the heavy metal (HM) bioavailability and declining the soil biological properties resulting from a direct application of solid digestate (SD). A low-temperature fruit biochar and pig-SD (BSD-0, BSD-1, BSD-2, BSD-4, BSD-8) co-application experiment was performed to evaluate enzyme activities and HM bioavailability in Cd-polluted greenhouse soil. The advantage of BSD co-applications compared to SD application was maintained the stable of pH and electrical conductivity (EC) in soil and was more effective to improve soil organic matter (OM). BSD-8 treatment significantly promoted the uptake of available nitrogen, available phosphorus, and available potassium by plants. The immobilization effect of BSD co-applications on Cu, Zn, and Cd was better than SD application. BSD-8 treatment has the best immobilization effect on Cd and the contents of bioavailable Cd was 0.167 mg kg−1. The optimal enzyme activities of invertase, urease, and alkaline phosphatase were shown in BSD-8 treatment, which were 0.027 mg glucose g−1 soil h−1, 88.654 mg NH3-N g−1 soil h−1, and 15.766 μmol PNP g−1 soil h−1, respectively. The activities of enzymes also were influenced by soil physicochemical properties and HM bioavailability. BSD-8 treatment was suggested as an appropriate mixing proportion to alleviate soil acidification and salinization, decreasing HM bioavailability and stimulating enzyme activities in Cd-polluted soil.

Cover crop enzyme activities and resultant soil ammonium concentrations under different tillage systems

Increased interest in managing agroecosystems for soil health has led to adoption of conservation management practices such as cover cropping and no-tillage. There is a dearth of knowledge surrounding cover crop residue N cycling and release, impacting subsequent N availability for the cash crop after cover crop termination. The microbial degradation of plant material and subsequent nutrient release is mediated by extracellular enzymes. This study used litter bag methodology to investigate the enzyme activities of three cover crop residues (cereal rye (CR) (Secale cereale L.), hairy vetch (HV) (Vicia villosa Roth), and a CR/HV mixture) in two tillage systems (no-tillage and reduced tillage) during the cover crop decomposition period in a corn (Zea mays L.) agroecosystem. The dynamics and amounts of β-glucosidase (EC 3.2.1.21) and urease (EC 3.5.1.5) enzyme activities on cover crop residue were quantified to determine if enzyme activities or stoichiometry are dependent on litter quality or can indicate N cycling potential. Results revealed that cover crop and tillage significantly impacted urease and β-glucosidase residue enzyme activity dynamics and amounts (p < 0.05). β-glucosidase activity of CR, HV, and a CR/HV mixture decreased by 76 %, 81 % and 77 % during the 2016 decomposition period, respectively. On average, urease activities of cover crop residues and soil ammonium concentrations increased during this period. In 2017, urease activities significantly decreased in all treatments (p < 0.05). β-glucosidase enzyme activity significantly decreased from 38 days after termination to 123 days after termination in all cover crop and tillage treatments (p < 0.05). Urease activities were significantly higher in the tillage treatments compared to no-tillage at the beginning of the 2017 decomposition period (p < 0.05). Soil ammonium concentrations significantly increased by 38 % across all treatments in 2017 during the decomposition period and concentrations were 12 times higher in 2017 at corn maturity compared to 2016. These results indicate potential for cover crops to stimulate residue β-glucosidase activity, suppress urease activity and ammonification, and increase soil N immobilization during corn N demanding growth stages. Furthermore, this study indicates that growers should consider optimum cover crop winter biomass accumulation levels to avoid potential N immobilization.

A Comparative Study of Soil and Foliar Nickel Application on Growth, Yield and Nutritional Quality of Barley (Hordeum Vulgare L.) Grown in Inceptisol

ABSTRACT Nickel (Ni) deficiency is common in intensively cultivated soils. As Ni is a costly input, thus, judicious use in agriculture is needed to address its deficiency economically. In view of deficiency of Ni, a field experiment was conducted to evaluate the responses for soil (SA), foliar (FA) and combination of these two methods of Ni application on growth, yield, nutritional quality and bio-chemical properties of soil using barley as a test crop. Foliar application of 0.2% NiSO4 significantly enhanced growth, yield, and nutrients concentration in grain as compared to SA. The highest grain and straw yield was in 5.0 kg SA Ni ha−1 + 0.2% FA of NiSO4 but it was statically at par with 0.2% FA of NiSO4. Application of 10 kg SA Ni ha−1 + 0.2% FA of NiSO4 resulted in a significant yield decrease. The maximum bacterial population was with 5 kg SA Ni ha−1, whereas actinomycetes population in 7.5 kg SA Ni ha−1. However, higher dose of Ni had a synergistic effect on the fungal population and urease enzyme activity. It was inferred that 0.2% FA of NiSO4 may be economically used over soil application to mitigate the deficiency of Ni in barley.