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1.
Sci Total Environ ; 951: 175652, 2024 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-39168344

RESUMEN

Bio-tiles are a biobased alternative to conventional tiles that utilise a promising technology called microbially induced calcium carbonate (CaCO3) precipitation (MICP). This technology has low energy requirements and also sequesters carbon. Bio-tiles have been made in previous work using a submersion method, however, the process required additives such as 0.3 M magnesium chloride to achieve bio-tiles that meet international standards. The current study aimed to improve the bio-tile strength properties with CaCO3 crystal seeding and a pumping method instead of the use of magnesium that also increases ionic strength. With this technique, cementation solution containing the required calcium and urea for the MICP reaction was pumped through a sealed mould in a series of programmed treatments. The highest concentration of ureolytic Sporosarcina pasteurii with an effective urease activity of 40 mmol NH4-N/L·min was found to be most beneficial to the breaking strength of the bio-tiles, as were the shortest retention times of 1 h between treatments. Seeding with CaCO3 crystals offered significant benefit to the MICP process. Pre-seeding of the geotextiles was explored and the mass of seeds initially present on the geotextiles was found to have a direct improvement on the breaking strength of 21-82 %, increasing with seed loading. The highest CaCO3 seed loading tested of 0.072 g seeds/cm2 geotextile resulted in bio-tiles with a breaking strength of 940 ± 92 N and a modulus of rupture of 16.4 ± 1.7 N/mm2, meeting international targets for extruded tiles with 6-10 % water absorption. When a seed loading of 0.021 g/cm2 was used instead, bio-tiles meeting targets for tiles with a water absorption of >10 % were produced at 628 ± 18 N and 10.5 ± 1.1 N/mm2.


Asunto(s)
Carbonato de Calcio , Sporosarcina , Carbonato de Calcio/química , Precipitación Química , Materiales de Construcción
2.
Front Bioeng Biotechnol ; 12: 1410203, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38994125

RESUMEN

Intensive agricultural activities could cause lead (Pb) bioaccumulation, threatening human health. Although the enzyme-induced carbonate precipitation (EICP) technology has been applied to tackle the aforesaid problem, the urease may denature or even lose its activity when subjected to a significant Pb2+ toxicity effect. To this end, the nano-hydroxyapatite (nHAP)-assisted EICP was proposed to reduce the mobility of Pb2+. Results indicated that a below 30% immobilization efficiency at 60 mM Pb2+ was attained under EICP. nHAP adsorbed the majority of Pb2+, preventing Pb2+ attachment to urease. Further, hydroxylphosphohedyphane or hydroxylpyromorphite was formed at 60 mM Pb2+, followed by the formation of cerussite, allowing hydroxylphosphohedyphane or hydroxylpyromorphite to be wrapped by cerussite. By contrast, carbonate-bearing hydroxylpyromorphite of higher stability (Pb10(PO4)6CO3) was developed at 20 mM Pb2+ as CO3 2- substituted the hydroxyl group in hydroxylpyromorphite. Moreover, nHAP helped EICP to form nucleated minerals. As a result, the EICP-nHAP technology raised the immobilization efficiency at 60 mM Pb2+ up to 70%. The findings highlight the potential of applying the EICP-nHAP technology to Pb-containing water bodies remediation.

3.
J Biosci Bioeng ; 138(1): 63-72, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38614831

RESUMEN

Among different microbial-induced calcium carbonate precipitation (MICCP) mechanisms utilized for biomineralization, ureolysis leads to the greatest yields of calcium carbonate. Unfortunately, it is reported that urea-induced growth inhibition can delay urea hydrolysis but it is not clear how this affects MICCP kinetics. This study investigated the impact of urea addition on the MICCP performance of Lysinibacillus sphaericus MB284 not previously grown on urea (thereafter named bio-agents), compared with those previously cultured in urea-rich media (20 g/L) (hereafter named bio-agents+ or bio-agents-plus). While it was discovered that initial urea concentrations exceeding 3 g/L temporarily hindered cell growth and MICCP reactions for bio-agents, employing bio-agents+ accelerated the initiation of bacterial growth by 33% and led to a 1.46-fold increase in the initial yield of calcium carbonate in media containing 20 g/L of urea. The improved tolerance of bio-agents+ to urea is attributed to the presence of pre-produced endogenous urease, which serves to reduce the initial urea concentration, alleviate growth inhibition, and expedite biomineralization. Notably, elevating the initial concentration of bio-agents+ from OD600 of 0.01 to 1, housing a higher content of endogenous urease, accelerated the initiation of MICCP reactions and boosted the ultimate yield of biomineralization by 2.6 times while the media was supplemented with 20 g/L of urea. These results elucidate the advantages of employing bio-agents+ with higher initial cell concentrations to successfully mitigate the temporary inhibitory effects of urea on biomineralization kinetics, offering a promising strategy for accelerating the production of calcium carbonate for applications like bio self-healing of concrete.


Asunto(s)
Bacillaceae , Carbonato de Calcio , Precipitación Química , Urea , Ureasa , Carbonato de Calcio/metabolismo , Carbonato de Calcio/farmacología , Carbonato de Calcio/química , Urea/metabolismo , Urea/farmacología , Bacillaceae/metabolismo , Cinética , Ureasa/metabolismo , Biomineralización , Medios de Cultivo/química
4.
Mikrochim Acta ; 190(10): 390, 2023 09 12.
Artículo en Inglés | MEDLINE | ID: mdl-37700117

RESUMEN

Zirconium copper oxide microflowers (Zr/CuO MF) based non-enzymatic sensor was developed for glucose detection in saliva, urine, and blood. An easy urea hydrolysis method was employed for the synthesis of the metal oxide and further calcined to improve the catalytic property. The flower-like morphology of the Zr/CuO was confirmed by SEM analysis and the presence of copper and zirconium was examined using energy dispersive X-ray analysis (EDAX). The Zr/CuO MF modified screen-printed electrodes exhibited excellent glucose sensing performance in 0.15 M NaOH medium and could quantify glucose in the range from 10 µM to 27 mM. A high sensitivity of 1.815 ± 0.003 mA mM-1 cm-2 was obtained for lower glucose concentration from 15 µM to 3 mM and 1.250 ± 0.006 mA mM-1 cm-2 for higher concentration glucose from 3 to 27 mM. The limit of detection of the fabricated sensor was found to be 0.8 µM. The sensor displayed high selectivity and stability towards glucose in different body fluids like saliva, urine, and blood serum at a working potential of 0.6 V (vs. Ag/AgCl). In saliva, urine, and serum samples, the sensor exhibited excellent recovery of 95-108, 92-108, and 93-101% in saliva, urine, and serum, respectively, with a relative standard deviation of less than 10%, demonstrating high accuracy and reliability of the sensor. The developed sensor is promising for developing an invasive and non-invasive point-of-care testing device for glucose detection.


Asunto(s)
Líquidos Corporales , Saliva , Suero , Cobre , Glucosa , Circonio , Reproducibilidad de los Resultados , Óxidos
5.
Nanotechnology ; 34(50)2023 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-37703834

RESUMEN

ß-FeOOH nanorods were prepared via the urea hydrolysis process with the average length of 289.1 nm and average diameter of 61.2 nm, while magneticα-Fe2O3/Fe3O4heterostructure nanorods were prepared via the urea calcination process withß-FeOOH nanorods as precursor, and the optimum conditions were the calcination temperature of 400 °C, the calcination time of 2 h, theß-FeOOH/urea mass ratio of 1:6. The average length, diameter, and the saturation magnetization of the heterostructure nanorods prepared under the optimum conditions were 328.8 nm, 63.4 nm and 42 emu·g-1, respectively. The Prussian blue test demonstrated that the heterostructure nanorods could be taken up by HepG2 cells, and cytotoxicity tests proved that the heterostructure nanorods had no significant effect on the viabilities of LO2 and HepG2 cells within 72 h in the range of 100-1600µg·ml-1. Therefore, magneticα-Fe2O3/Fe3O4heterostructure nanorods had better biocompatibility with LO2 and HepG2 cells.

6.
Environ Sci Pollut Res Int ; 30(34): 82014-82030, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37316626

RESUMEN

Carbon disulfide (CS2) is one of the sulfur components that are naturally present in petroleum fractions. Its presence causes corrosion issues in the fuel facilities and deactivates the catalysts in the petrochemical processes. It is a hazardous component that negatively impacts the environment and public health due to its toxicity. This study used zinc-carbon (ZC) composite as a CS2 adsorbent from the gasoline fraction model component. The carbon is derived from date stone biomass. The ZC composite was prepared via a homogenous precipitation process by urea hydrolysis. The physicochemical properties of the prepared adsorbent are characterized using different techniques. The results confirm the loading of zinc oxide/hydroxide carbonate and urea-derived species on the carbon surface. The results were compared by the parent samples, raw carbon, and zinc hydroxide prepared by conventional and homogeneous precipitation. The CS2 adsorption process was performed using a batch system at atmospheric pressure. The effects of adsorbent dosage and adsorption temperatures have been examined. The results indicate that ZC has the highest CS2 adsorption capacity (124.3 mg.g-1 at 30 °C) compared to the parent adsorbents and the previously reported data. The kinetics and thermodynamic calculation results indicate the spontaneity and feasibility of the CS2 adsorption process.


Asunto(s)
Disulfuro de Carbono , Gasolina , Sustancias Peligrosas , Disulfuro de Carbono/análisis , Disulfuro de Carbono/química , Disulfuro de Carbono/toxicidad , Zinc/química , Carbono/química , Microondas , Adsorción , Sustancias Peligrosas/análisis , Sustancias Peligrosas/química , Sustancias Peligrosas/toxicidad
7.
Sci Total Environ ; 895: 165050, 2023 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-37355135

RESUMEN

Using the biomimetic process known as microbially induced calcium carbonate precipitation (MICP), the growth of bio-tiles was investigated as an alternative to conventionally fired ceramic tiles which require operating temperatures above 1000 °C, therefore adding to global carbon emissions. The ureolytic activity of Sporosarcina pasteurii was controlled by centrifuging and dilution with fresh yeast extract media. The bio-tiles were grown using a novel submersion method in which custom moulds were placed in exact positions within the bio-reactor and each was mixed individually from beneath. Five parameters were optimised to achieve bio-tiles (dimensions of 100 × 100 × 10 mm) of breaking strength comparable to conventional tiles of equivalent thickness. By optimising ureolytic activity (4.0 mmol/L·min), the cementation solution concentration (0.3 M), the particle size distribution (D10 = 312 µm; D50 = 469 µm), the volume of cementation solution, as well as the addition of supplemental magnesium (0.3 M), bio-tiles with a breaking strength 637 N ± 60 N and a modulus of rupture of 13.0 N/mm2 ± 2.3 N were produced. These parameters exceed the conventional standards of breaking strength and modulus of rupture of 600 N and 8 N/mm2, respectively, the standards set for tiles with a water absorption above 10 %. This is also the first time that an optimum CaCO3 precipitation rate constant has been identified (0.11-0.18 day-1) for producing bio-tiles that meet the strength properties of conventional extruded ceramic tiles. The tile manufacturing technique described in this study is easy to operate and scale since multiple bio-tiles can be produced in larger cementation tanks. This natural tile making process also benefits the environment by operating at room temperature.


Asunto(s)
Carbonato de Calcio , Urea , Temperatura , Agua , Precipitación Química
8.
Front Bioeng Biotechnol ; 11: 1118993, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37139046

RESUMEN

The sand production during oil and gas extraction poses a severe challenge to the oil and gas companies as it causes erosion of pipelines and valves, damages the pumps, and ultimately decreases production. There are several solutions implemented to contain sand production including chemical and mechanical means. In recent times, extensive work has been done in geotechnical engineering on the application of enzyme-induced calcite precipitation (EICP) techniques for consolidating and increasing the shear strength of sandy soil. In this technique, calcite is precipitated in the loose sand through enzymatic activity to provide stiffness and strength to the loose sand. In this research, we investigated the process of EICP using a new enzyme named alpha-amylase. Different parameters were investigated to get the maximum calcite precipitation. The investigated parameters include enzyme concentration, enzyme volume, calcium chloride (CaCl2) concentration, temperature, the synergistic impact of magnesium chloride (MgCl2) and CaCl2, Xanthan Gum, and solution pH. The generated precipitate characteristics were evaluated using a variety of methods, including Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). It was observed that the pH, temperature, and concentrations of salts significantly impact the precipitation. The precipitation was observed to be enzyme concentration-dependent and increase with an increase in enzyme concentration as long as a high salt concentration was available. Adding more volume of enzyme brought a slight change in precipitation% due to excessive enzymes with little or no substrate available. The optimum precipitation (87%) was yielded at 12 pH and with 2.5 g/L of Xanthan Gum as a stabilizer at a temperature of 75°C. The synergistic effect of both CaCl2 and MgCl2 yielded the highest CaCO3 precipitation (32.2%) at (0.6:0.4) molar ratio. The findings of this research exhibited the significant advantages and insights of alpha-amylase enzyme in EICP, enabling further investigation of two precipitation mechanisms (calcite precipitation and dolomite precipitation).

9.
J Environ Manage ; 326(Pt A): 116653, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36410300

RESUMEN

For the sake of exploring a new economical and low-carbon alternative for real nitrate-containing wastewater treatment, a new combined partial denitrification-anammox with urea hydrolysis (U-PD-Anammox) process was developed. The nitrogen removal performance of this process was investigated through long-term operation in a sequencing batch reactor (SBR) and two submerged anaerobic biological filters (SABF). Results showed that the average NO3--N to NO2-N transformation ratio improved to 82.6% with organic carbon source to NO3-N ratio of 1.8, and urea hydrolysis provided sufficient NH4+-N and inorganic carbon to anammox process for nitrogen removal. The influent NH4+-N/NO2--N ratio for subsequent anammox reactor could be adjacent to the optimal ratio of 1.32 during the whole operation. The combined process showed efficient nitrogen removal performance with 85% NO3--N removal, 93.8% total nitrogen removal and total nitrogen loading rate as 1.1 ± 0.5 kg N/(m3·d). High-throughput sequencing analysis results revealed that Genera Thauera, Hyphomicrobium and Candidatus Brocadia were the dominant species responsible for partial denitrification, urea hydrolysis and anammox, respectively. The proposed process was more economically and environmental-friendly than the traditional denitrification process with 51.7% operational cost reduction, 99.7% N2O and 60% CO2 emission decrement, facilitating the sustainable development of the nitrate-containing wastewater treatment industry in the future.


Asunto(s)
Nitratos , Purificación del Agua , Carbono , Urea , Desnitrificación , Hidrólisis , Oxidación Anaeróbica del Amoníaco , Dióxido de Nitrógeno , Óxidos de Nitrógeno , Nitrógeno
10.
Water Res ; 222: 118891, 2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-35907300

RESUMEN

Human and animal source-separated urine, stored and allowed to naturally hydrolyse (the bio-catalysed transformation of urea to ammonia and bicarbonate), has been used for millennia as a fertiliser in agriculture. In a context of growing water scarcity and climate uncertainty, source-separation of urine is facing a strong revival thanks to the emergence of cost-effective waterless collection systems. Concomitantly, urine source-separation can be used as a method for nutrient recovery and subsequent reuse. In its simplest form, such recovery consists of collection followed by urea hydrolysis and storage as sole treatment. Numerous guidelines, including by the World Health Organisation, consider that this is sufficient to stabilise the nutrients and inactivate any potential pathogens in the urine. However, it is still unclear whether said urine is effectively free from other compounds of concern, such as anthropogenic micropollutants with known toxicological effects. Moreover, it is also currently unknown if the metabolites produced by human consumption of these products behave in similar way during short- and long-term storage i.e. whether any changes in chemical structure mean that these could be sorbed and/or precipitated in a different way, or if they can potentially be degraded by the biomass inherently present in urine collection systems. Finally, there is currently no knowledge of whether the observed concentrations of micropollutants in stored hydrolysed urine could potentially have toxicological effects if/when applied to soils and edible crops. To fill these research gaps, 20 commonly consumed compounds were selected in this study and their concentrations in the liquid and solid phases studied in the short- and long-term (up to ≥ 2 years). During the initial process of urea hydrolysis (≤ 5 days), ethyl-glucuronide was the sole compound effectively removed (by deconjugation), while only two other compounds, erythromycin and its metabolite, saw a reduction in their concentration (likely due to biomass sorption). Subsequently, during early storage (≤ 15 days), only three additional compounds were removed: paracetamol (> 99%), acesulfame (11.5%) and carbamazepine-10,11 epoxide (40.7%). Finally, long-term storage of up to 24 months did not result in any further significant removal for any of the measured compounds, indicating that the procedure of hydrolysis + storage is not effective for the removal of anthropogenic micropollutants. The results of this investigation raise strong concerns about the direct reuse of hydrolysed/stored human source-separated urine, and evidence the need for post-processing before implementation as fertiliser into edible crops due to the inherent toxicological risk, particularly to infants.


Asunto(s)
Fertilizantes , Urea , Agricultura , Amoníaco/análisis , Fertilizantes/análisis , Humanos , Hidrólisis , Urea/química , Orina/química
11.
Front Bioeng Biotechnol ; 10: 889717, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35586552

RESUMEN

Lead and copper ions from wastewater induced by metallurgical processes are accumulated in soils, threatening plant and human health. The bioinspired calcium carbonate precipitation is proven effective in improving the cementation between soil particles. However, studies on capsulizing heavy metal ions using the bioinspired calcium carbonate precipitation are remarkably limited. The present study conducted a series of test tube experiments to investigate the effects of bacterial culture and calcium source addition on the remediation efficiency against lead and copper ions. The calcium carbonate precipitation was reproduced using the Visual MINTEQ software package to reveal the mechanism affecting the remediation efficiency. The degradation in the remediation efficiency against lead ions relies mainly upon the degree of urea hydrolysis. However, higher degrees of urea hydrolysis cause remediation efficiency against copper ions to reduce to zero. Such high degree of urea hydrolysis turns pH surrounding conditions into highly alkaline environments. Therefore, pursuing higher degrees of urea hydrolysis might not be the most crucial factor while remedying copper ions. The findings shed light on the importance of modifying pH surrounding conditions in capsulizing copper ions using the bioinspired calcium carbonate precipitation.

12.
Front Bioeng Biotechnol ; 10: 849631, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35223803

RESUMEN

Heavy metal contamination not only causes threat to human health but also raises sustainable development concerns. The use of traditional methods to remediate heavy metal contamination is however time-consuming, and the remediation efficiency may not meet the requirements as expected. The present study conducted a series of test tube experiments to investigate the effect of calcium source on the lead and copper removals. In addition to the test tube experiments, numerical simulations were performed using Visual MINTEQ software package considering different degrees of urea hydrolysis derived from the experiments. The remediation efficiency degrades when NH4 + and OH- concentrations are not sufficient to precipitate the majority of Pb2+ and Cu2+. It also degrades when CaO turns pH into highly alkaline conditions. The numerical simulations do not take the dissolution of precipitation into account and therefore overestimate the remediation efficiency when subjected to lower Pb(NO3)2 or Cu(NO3)2 concentrations. The findings highlight the potential of applying the enzyme-induced carbonate precipitation to lead and copper remediations.

13.
Chemosphere ; 288(Pt 2): 132586, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34718026

RESUMEN

The adsorptive removal performance of strontium (Sr) through bio-mineralization metabolism under various parameters was evaluated in this study. The primary mechanism of bio-mineralization used in this study was the urea hydrolysis process through bacterial enzymatic catalysis. Bacillus sp, which was isolated from river sediment, was used as a ureolytic bacteria. Various environmental conditions were set as different initial concentrations of Sr (10, 50, 100, 200, and 500 mg/L), and various ratios of Mg/Ca (4, 2, 1, 0.5, and 0.25). The concentrations of Sr2+, Ca2+, and Mg2+ in the solution of the batch experiment were measured to identify the bio-mineralization performance and the removal rate of Sr. In addition, the main Sr removal mechanism of ureolytic bacteria was identified. As a result, for Sr removal of bacteria, the bio-mineralization mechanism was more predominant than the adsorption of Sr. The rapid growth and high nucleation site production were observed when the initial concentration of Sr2+ increased and the Mg/Ca ratio was lowered, resulting in high biomineralization performance and Sr removal rate. The main phases of carbonate minerals formed in the presence of Sr, Ca, and Mg were SrCO3 and SrCa(CO3)2. Mg2+ could retard the bacterial growth and participate in the formation of carbonate minerals, when a large amount of Mg2+ was present. Furthermore, the desorption rate of Sr2+ from bacterial pastes containing the carbonate minerals increased as the concentration of HCl increased, although the carbonate minerals were in a stable state.


Asunto(s)
Estroncio , Adsorción
14.
J Environ Manage ; 304: 114307, 2022 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-34942547

RESUMEN

Microbial Induced Calcite Precipitation (MICP) via biostimulation of urea hydrolysis is a biogeochemical process in which soil indigenous ureolytic microorganisms catalyse the decomposition of urea into ammonium and carbonate ions which, in the presence of calcium, precipitate as calcium carbonate minerals. The environmental conditions created by urine in soil resemble those induced by MICP via urea hydrolysis. Thus, this study assesses the suitability of a waste product, cow urine, as a source of nutrients for MICP. Urea stability in fresh and sterilised urine were monitored for a month to cover the length of a potential MICP intervention. An experimental soil column set up was used to compare the soil response to the repeated application of fresh and sterilised cow urine, within pH of 7 and 9, and the chemical-based solution. Urea hydrolysis and the carbonate content in solution were monitored to assess the suitability of the proposed alternative. In addition, the nitrification process was monitored. Key findings indicated i) urea concentration and stability in fresh and sterilised cow urine are suitable for MICP application; ii) the soil response to treatments of cow urine within pH of 7 and 9 are similar to the chemical-based solution; and iii) increasing solution pH results in a faster activation of ureolytic microorganisms and higher carbonate content in solution. These results demonstrate that cow urine is a suitable substitute of the chemical-based MICP application.


Asunto(s)
Carbonato de Calcio , Suelo , Animales , Bovinos , Precipitación Química , Nutrientes , Arena
15.
Carbohydr Polym ; 275: 118584, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34742403

RESUMEN

Here, Cotton fabric was functionalized via hybrid coating including 2D MgAl LDH (layered double hydroxide) and SA (stearic acid). The urea hydrolysis was employed for construction of vertically aligned LDH on surface of cellulose fibers under hydrothermal condition. The in situ formation mechanism of LDH on cotton surface was nucleation, growth, and interaction with activated cellulose chains. The partial cellulose ionization in the alkaline solution led to nucleophilic behavior towards electron deficient atom. The effect of different ageing, synthesis temperature, and amount of SA were investigated and optimized at 100 °C for 24 h with 0.05 M. The superhydrophobic surface architecture of treated cotton with hierarchical micro/nanostructure was inspired from the Taro leaf structure with continuous contact line presented WCA of 154 ° and CAH of 9 °. The Cotton@LDH@SA exhibited efficient oil/water separation after several washes (>90%) with good stain resistant. Also, the physico-mechanical properties were studied.


Asunto(s)
Celulosa/química , Colocasia/química , Fibra de Algodón , Hidróxidos/química , Urea/química , Aluminio/química , Hidrólisis , Interacciones Hidrofóbicas e Hidrofílicas , Magnesio/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Ácidos Esteáricos/química , Textiles , Humectabilidad , Difracción de Rayos X/métodos
16.
Anim Nutr ; 7(4): 989-996, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34738029

RESUMEN

Inefficient dietary nitrogen (N) conversion to microbial proteins, and the subsequent use by ruminants, is a major research focus across different fields. Excess bacterial ammonia (NH3) produced due to degradation or hydrolyses of N containing compounds, such as urea, leads to an inefficiency in a host's ability to utilize nitrogen. Urea is a non-protein N containing compound used by ruminants as an ammonia source, obtained from feed and endogenous sources. It is hydrolyzed by ureases from rumen bacteria to produce NH3 which is used for microbial protein synthesis. However, lack of information exists regarding urea hydrolysis in ruminal bacteria, and how urea gets to hydrolysis sites. Therefore, this review describes research on sites of urea hydrolysis, urea transport routes towards these sites, the role and structure of urea transporters in rumen epithelium and bacteria, the composition of ruminal ureolytic bacteria, mechanisms behind urea hydrolysis by bacterial ureases, and factors influencing urea hydrolysis. This review explores the current knowledge on the structure and physiological role of urea transport and ureolytic bacteria, for the regulation of urea hydrolysis and recycling in ruminants. Lastly, underlying mechanisms of urea transportation in rumen bacteria and their physiological importance are currently unknown, and therefore future research should be directed to this subject.

17.
Biosensors (Basel) ; 11(6)2021 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-34201174

RESUMEN

The development of in situ analytical devices has gained outstanding scientific interest. A solid sensing membrane composed of 1,2-naphthoquinone-4-sulfonate (NQS) derivatizing reagent embedded into a polymeric polydimethylsiloxane (PDMS) composite was proposed for in situ ammonium (NH4+) and urea (NH2CONH2) analysis in water and urine samples, respectively. Satisfactory strategies were also applied for urease-catalyzed hydrolysis of urea, either in solution or glass-supported urease immobilization. Using diffuse reflectance measurements combined with digital image processing of color intensity (RGB coordinates), qualitative and quantitative analyte detection was assessed after the colorimetric reaction took place inside the sensing membrane. A suitable linear relationship was found between the sensor response and analyte concentration, and the results were validated by a thymol-PDMS-based sensor based on the Berthelot reaction. The suggested sensing device offers advantages such as rapidity, versatility, portability, and employment of non-toxic reagents that facilitate in situ analysis in an energy-efficient manner.


Asunto(s)
Naftoquinonas/química , Urea/metabolismo , Ureasa/metabolismo , Colorimetría , Dimetilpolisiloxanos , Polímeros , Ureasa/análisis , Agua/química
18.
Front Microbiol ; 12: 721478, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34322113

RESUMEN

[This corrects the article DOI: 10.3389/fmicb.2021.646748.].

19.
Materials (Basel) ; 14(9)2021 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-33922871

RESUMEN

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.

20.
Front Microbiol ; 12: 646748, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33897660

RESUMEN

Microbially induced calcium carbonate precipitation (MICP) is a bio-geochemical process involving calcium carbonate precipitation and possible co-precipitation of other metals. The study investigated the extent to which a urease-positive bacterium, Sporosarcina pasteurii, can tolerate a range of metals (e.g., Cu, Zn, Pb, Cd, and Sr), and analyzed the role of calcium carbonate bioprecipitation in eliminating these divalent toxicants from aqueous solutions. The experiments using S. pasteurii were performed aerobically in growth media including urea, CaCl2 (30 mM) and different metals such Cu, Zn, Pb, and Cd (0.01 ∼ 1 mM), and Sr (1 ∼ 30 mM). Microbial growth and urea degradation led to an increase in pH and OD600, facilitating the precipitation of calcium carbonate. The metal types and concentrations contributed to the mineralogy of various calcium carbonates precipitated and differences in metal removal rates. Pb and Sr showed more than 99% removal efficiency, whereas Cu, Zn, and Cd showed a low removal efficiency of 30∼60% at a low concentration of 0.05 mM or less. Thus the removal efficiency of metal ions during MICP varied with the types and concentrations of divalent cations. The MICP in the presence of divalent metals also affected the mineralogical properties such as carbonate mineralogy, shape, and crystallinity.

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