Urease Enzyme Activity Research Articles

The effect of the antibiotic tetracycline hydrochloride on the biotransformation of urea when exposed to soil nitrifying strains

Introduction. The consequences of uncontrolled use of antibiotics in agriculture are an urgent problem of environmental hygiene. Tetracycline can enter the soil with the urine of domestic animals, inhibit the vital activity of soil bacterial strains and inhibit the processes of enzymatic hydrolysis of urea (carbamide), disrupting the global nitrogen cycle in nature. The lack of both quantitative and qualitative criteria for assessing this influence determined the relevance of the research. Materials and methods. The studies were carried out using the “Stayer” chromatographic system with cationic and anionic separating columns and exclusive analysis methods developed by the authors. When modelling solutions of heavy metals, an atomic absorption spectrometer MGA - 915MD with ETA was used. The objects of research were model solutions of carbamide with different content of inhibiting substances. As a source of urease and strains of Nitrobacter and Nitrosomonas, sod-podzolic soil from the Educational and Experimental Soil-Ecological Center “Chashnikovo” of Lomonosov Moscow State University was used. Results. An improved, more rapid chromatographic method for the analysis of urea in water is proposed compared to the method described by the authors earlier. The inhibitory effect of the antibiotic tetracycline hydrochloride on the process of biotransformation of nitrite into nitrate caused by Nitrobacter strains has been shown. No significant effect of the antibiotic on the biotransformation of urea into ammonium and ammonium into nitrite under the action of Nitrosomonas strains has been established. Limitations. The studies were carried out on the model of water systems, which included an aqueous phase containing different concentrations of the antibiotic, soil suspension, urea, heavy metal ions at a temperature of t = 30 ○C, pH ~ 6.5. The influence of salt background, pH, and temperature on biotransformation has not been studied, which could, without changing the overall picture, reveal nuances in the kinetics of the main processes. Conclusion. Studies have shown the absence of the effect of the antibiotic tetracycline hydrochloride on the kinetics of the decomposition of urea to ammonium and carbon dioxide due to urease enzymatic activity; there is no effect of the antibiotic on the oxidation of ammonium to nitrites by Nitrosomonas strains. It was found: selective inhibitory effect of an antibiotic during the oxidation of nitrite to nitrate, due to Nitrobacter strains; inhibition of biotransformation processes by chromium ions along the entire chain of transformations from urea to nitrate; and the inhibitory effect of excess oxygen on the totality of biotransformation processes during air bubbling through the aqueous phase.

The Effects of Catch Crops on Properties of Continuous Cropping Soil and Growth of Vegetables in Greenhouse

Continuous cropping has become a key factor limiting the sustainable development of greenhouse vegetables. It is a matter of great importance to maintain and improve the effective fertility of greenhouse soil. Catch crops planted as green manure is an effective method to improve soil quality. In order to determine the effects of catch crops on soil characteristics and the growth of afterculture vegetables, onion, corn, wheat, soybean and cabbage were planted as catch crops for two years during the summer fallow season, with no catch crop as CK. The results showed that the total porosity and organic matter content of the soil, with corn and wheat as catch crops, was significantly increased by 2.93%, 5.25% and 21.32%, 51.61%, respectively, while pH was decreased, compared with CK. The urease, sucrase, invertase, catalase and FDA enzyme activity of the soil with corn and wheat as catch crops was significantly increased by 30.14% and 30.21%, 14.81% and 25.31%, 15.43% and 15.21%, 29.37% and 28.69%, 46.32% and 44.23%. Meanwhile, the enzyme activity of the soil was increased with each catch crop planted. The amount of culturable bacteria and actinomycetes in the soil with corn and wheat as catch crops was increased by 33.42% and 38.12% at the period of 150dayII, while fungi was decreased by 59.95%. The yield of vegetables with corn and wheat as catch crops significantly increased by 5.59~13.33% and 4.35~11.18% compared with CK. Overall, catch crops could improve the soil quality as well as the growth of afterculture vegetables.

Soil Microbial Community and Enzymatic Activity of Grasslands under Different Use Practices: A Review

The usage of grassland significantly affects the microbial and biochemical parameters of soil epipedons. The use of grasslands (by mowing, grazing, and mowing and grazing) affects the dominance of bacteria in abundance relative to fungal populations. This was particularly noticeable when manual mowing was applied. In general, the highest number of microorganisms occurred during spring and summer, which should be associated with the intensity of growth of root systems of grass vegetation. It was noted that the grazing system caused an increase in the enzymatic activity of urease and slightly less dehydrogenases and acid and alkaline phosphatase. Therefore, microbial abundance and enzymatic activity are considered as indicator parameters to evaluate the biological soil environment. They are highly probable estimates of soil fertility and ecosystem biodiversity.

Gossypol from Gossypium spp. Inhibits Helicobacter pylori Clinical Strains and Urease Enzyme Activity: Bioactivity and Safety Assessments

This study investigates the inhibitory activities of gossypol, a natural polyphenolic compound from Gossypium spp., against Helicobacter pylori (HP) clinical strains and a urease enzyme that plays a key role in the pathogenesis of HP. Gossypol was detected to exhibit a bacteriostatic action against all the HP strains tested with minimum inhibitory concentration (MIC) values ranging from 3.51 to 4.14 µg/mL. The activity of HP urease (HPU) was efficiently impeded by gossypol with a 50% inhibitory concentration (IC50) value of 3.3 µM using an Electrospray Ionization–Mass Spectrometry (ESI-MS)-based method. The in vitro cytotoxicity assay showed no significant cytotoxic properties of gossypol against human gastric epithelial cells. Additionally, molecular docking studies were performed to assess the binding mode and the molecular interactions of gossypol with HPU with a binding affinity value of −8.1 kcal/mol compared with an HPU–acetohydroxamic acid (a standard urease inhibitor) docking complex (–6.1 kcal/mol). The overall results reveal that gossypol might help fight against HP infection by two mechanisms of action: inhibition of the growth of HP and inhibition of urease.

Wood vinegar facilitated growth and Cd/Zn phytoextraction of Sedum alfredii Hance by improving rhizosphere chemical properties and regulating bacterial community

Soil Cd and Zn contamination has become a serious environmental problem. This work explored the performance of wood vinegar (WV) in enhancing the phytoextraction of Cd/Zn by hyperaccumulator Sedum alfredii Hance. Rhizosphere chemical properties, enzyme activities and bacterial community were analyzed to determine the mechanisms of metal accumulation in this process. Results demonstrated that, after 120 days growth, different times dilution of WV increased the shoot biomass of S. alfredii by 85.2%–148%. In addition, WV application significantly increased soil available Cd and Zn by lowing soil pH, which facilitated plant uptake. The optimal Cd and Zn phytoextraction occurred from the 100 times diluted WV (D100), which increased the Cd and Zn extraction by 188% and 164%, compared to CK. The 100 and 50 times diluted WV significantly increased soil total and available carbon, nitrogen and phosphorus, and enhancing enzyme activities of urease, acid phosphatase, invertase and protease by 10.1–21.4%, 29.1–42.7%,12.2–38.3% and 26.8–85.7%, respectively, compared to CK. High-throughput sequencing revealed that the D 100 significantly increased the bacterial diversity compared to CK. Soil bacterial compositions at phylum, family and genera level were changed by WV addition. Compared to CK, WV application increased the relative abundances of genus with plant growth promotion and metal mobilization function such as, Bacillus, Gemmatimonas, Streptomyces, Sphingomonas and Polycyclovorans, which was positively correlated to biomass, Cd/Zn concentrations and extractions by S. alfredii. Structural equation modeling analysis showed that, soil chemical properties, enzyme activities and bacterial abundance directly or indirectly contributed to the biomass promotion, Cd, and Zn extraction by S. alfredii. To sum up, WV improved phytoextraction efficiency by enhancing plant growth, Cd and Zn extraction and increasing soil nutrients, enzyme activities, and modifying bacterial community.

Do Mixed Pinus yunnanensis Plantations Improve Soil’s Physicochemical Properties and Enzyme Activities?

Many survival and ecological problems have emerged in Pinus yunnanensis pure pine forest plantations that are usually assumed to be solved by creating mixed plantations. On this basis, we determined the physicochemical properties and enzyme activities of three soil layers in pure and three types of mixed P. yunnanensis plantation stands (admixed species: Alnus nepalensis, Celtis tetrandra, and Quercus acutissima) in Southwest China. We used one-way ANOVA with Tukey’s test to analyze the effects of plantation type and depth on the soil’s properties and variations among different depths. Principal component analysis combined with cluster analysis was used to evaluate the soil quality of different forest types comprehensively. The results showed that the stand with a mixing proportion of 2:1 of P. yunnanensis and A. nepalensis, C. tetrandra, and Q. acutissima had higher total porosity, moisture content, total nitrogen, available phosphorus, total phosphorus, sucrase, urease, and catalase enzyme activities than other proportions of mixed forest and P. yunnanensis pine pure forest. In general, the mixed P. yunnanensis plantation could improve the soil quality, especially its chemical properties and enzymes. This study provides a basis for creating a mixed-mode of P. yunnanensis and other tree species that can not only improve the economy of forest land but also enhance the ecological value.

Ebselen’s Potential to Inhibit Planktonic and Biofilm Growth of Neisseria mucosa

Background: Antibiotic resistance of various bacterial communities remains a global burden in the healthcare industry. Biofilm formation is one of the resistance mechanisms acquired by bacterial communities in order to reverse the action of antibiotics. There is an urgent need for the discovery of novel antimicrobials and novel approaches to tackle this problem. However, it is very expensive and challenging to develop new antibiotics. Drug repurposing is an efficient strategy which reduces time and cost associated with drug discovery. Objective: In the current study, anti-microbial and antibiofilm potential of an organoselenium clinical molecule Ebselen against Neisseria mucosa has been elucidated. Methods: Ebselen Antibacterial studies include Minimum Inhibitory Concentration (MIC), growthkill, Colony Forming Unit (CFU) assays and intracellular Reactive Oxygen Species (ROS) accumulation studies. Antibiofilm studies included inhibition, eradication and cell surface hydrophobicity assays, quantification of Extracellular Polymeric Substance (EPS) and eDNA and for anti-quorum sensing activity, protease and urease enzyme activities were elucidated. Results: Ebselen showed efficient bactericidal activity as indicated by its low MIC values, bacterial growth inhibition over time and its ability to prevent clonal propagation in this bacterium. Increased accumulation of ROS in Ebselen treated cells indicates radical mediated induction of bacterial death. Interestingly, Ebselen inhibited and distorted matured biofilms by degrading the eDNA component of the EPS layer. Ebselen also attenuated quorum-sensing pathway as indicated by decreased urease and protease enzyme activities. Conclusion: Taken together, these results paved the way to repurpose Ebselen as a potential drug target to curb Neisseria mucosa infections.

Application of humic acid compound fertilizer for increasing sweet potato yield and improving the soil fertility

Combined application of humic acid (HA) and multi-nutrient fertilizer improve nutrient utilization and increase crop yield. To give insight about the application of HA compound fertilizer in sweet potato production, a field experiment was conducted the effect of humic acid-nitrogen, phosphorus, and potassium compound fertilizer (HA-NPK) on soil nutrient contents, soil enzyme activity, soil microorganism community structure and yield of sweet potato. Results showed that compared to nitrogen, phosphorus, and potassium compound fertilizer (NPK) treatment, the activated humic acid- nitrogen, phosphorus, and potassium compound fertilizer (HA-NPK1) and non-activated humic acid- nitrogen, phosphorus, and potassium compound fertilizer (HA-NPK2) treatment significantly increased the plant biomass and storage root yield. Increase in yield from application of HA-NPK1 was significantly larger than those from HA-NPK2. The HA-NPK1 treatment greatly increased the content of readily available phosphorus, potassium and soil organic matter, enhanced the enzyme activity of soil urease, invertase, alkaline phosphatase and catalase. The numbers of soil bacteria, fungi and actinomycetes in the HA-NPK1 treatment were significantly higher than the NPK treatment. In conclusion, the application of the activated HA-NPK in sweet potato production could be used effectively to increase soil quality, facilitate the growth of sweet potato and increase its yield under similar conditions to this work.

Effects of artificial nitrogen deposition on the forest floor and soil chemistry in chestnut-leaved oak (Quercus castaneifolia) plantation in northern Iran

Human demand for food and energy has led to significant changes in the level of reactive nitrogen (N) released to the atmosphere and then deposited in the biosphere. This study aimed to investigate the impact of the deposition of artificial N on the forest floor and on the soil chemical properties in an oak (Quercus castaneifolia C.A. Mey.) plantation in northern Iran. Twelve plots of 200 m2 (20 m × 10 m) were set up in the study area. Four N treatments were considered: zero (control), 50 (low), 100 (medium), and 150 (high) kg N·ha−1·year−1. N in the form of NH4NO3 solution was manually sprayed onto the understory plots monthly for 1 year. The total N, phosphorus (P), potassium (K), and organic carbon (OC) of the forest floor were measured. Soil N, available P, available K, pH, EC (electrical conductivity), OC, microbial biomass C (MBC), and urease enzyme activity were measured in the 0–10 cm depth. The concentration of total N and P of the forest floor was significantly higher in the high-N treatment. The total concentration of N (+36%), the urease activity (+44%), and EC (+12%) of soil increased with raising the high-N treatment compared to the control, but the MBC (−20%), available P (−28%), and available K (−15%) were significantly reduced in the high-N treatment. Our results were obtained with simulated deposition rates that exceed ambient fluxes, but ambient N deposition is nevertheless high in our study area.

Antiureolytic activity of new water-soluble thiadiazole derivatives: Spectroscopic, DFT, and molecular docking studies

Two new water-soluble thiadiazole compounds are prepared and characterized with various techniques. These compounds, 5-amino-1,3,4-thiadiazole hydrochloride (1) and 5-amino-3-(N-propane-2-imine)-1,3,4-thiadiazole chloride salt (2) were synthesized via Mannich reaction, and characterized by microelemental analysis, and some spectroscopic means (FTIR, UV–Vis, 1H NMR, 13C NMR and mass), in addition to single-crystal X-ray diffraction for compound 2. DFT calculations were conducted to study their geometry optimization, vibrational spectra, MEP maps, and NBO analysis. In addition, TD-DFT calculations were performed to study their absorption spectra. The prepared compounds were tested against Jack beans urease enzyme (in vitro) to indicate their antiureolytic activity potency. The activity of the enzyme was measured under optimal conditions, before and after mixing with the prepared organic compounds. The results showed that both compounds have potentially inhibited the enzyme activity with respect to their IC50 values: 13.76 µM ± 0.15 for 1, and 18.81 µM ± 0.18 for 2. These values are even lower than that of thiourea (21.40 ± 0.21 µM) as a standard inhibitor. The inhibition activity of urease enzyme was confirmed by a Lineweaver-Burk plot. According to the kinetic parameters obtained from the Lineweaver–Burk plot, the inhibition of urease enzyme by compounds 1 and 2 seems to be non-competitive. Molecular docking studies of the prepared compounds 1 and 2 were performed in order to interpret the obtained biological results and to investigate their interactions with the urease enzyme active site. These studies reveal that compounds 1 and 2 are good candidates as inhibitors for urease enzyme. Moreover, compound 1 exhibits a higher promising inhibition activity.

Environmentally significant indicators of mountain meadow soils in Azerbaijan

The most widespread soils in the Republic of Azerbaijan are mountain-meadow soils. The aim of the research was a comprehensive and comparative study of morphodiagnostic parameters, physical and chemical properties, as well as the biochemical activity of natural and anthropogenically modified biogeocenoses of the Kedabey region. The area has unique flora and fauna. Surroundings of the villages Gara Murad, Kichik Garamurad, Saratovka and others were investigated. The research was carried out on virgin and cultivated lands in villages. The degree of mineralization of the rivers Zayamchay and Chekhrichay ranges from 140 to 430 mg. The groundwater level in these areas exceeds 2 m, salinization processes are active. A herbarium was collected and the floristic composition of natural cenoses was determined. Invertebrates were also collected and the dominant composition of the fauna of natural cenoses was determined. Of the saprophages in these biocenoses, woodlice of the genus Hemilepisthus and Armadillidium are widely used. The most intensive decomposition of the remains of cereal vegetation is observed in the soil of the coastal strip (65.9%). In the natural cenosis, the rate of destruction of saltwort and salt-tolerant grass vegetation reaches 44.3%. The main role in the destruction of plant remains is played by a group of saprphages, which actively use plant litter. The decomposing material reaches its final stage of microbiological transformation. The duration and amount of CO2 in different soil horizons were also studied. It has been established that with increasing depth, the amount of carbon dioxide decreases. The hydrolytic activity of invertase and urease enzymes in the studied soils can be assessed as very weak. Comparative results of all these agrochemical studies helped to develop virgin soils in agriculture on the plains and achieve high productivity.

Transient application of foliar urea with N-(n-Butyl) thiophosphoric triamide on N metabolism of pineapple under controlled condition

Traditional fertilization and the loss of Nitrogen (N) is a common phenomenon in agriculture. Application of urea with urease inhibitor is an alteration measure of urea hydrolysis and N metabolism. Hence, the objective of this study was to determine the short-term foliar application effect of N-(n‑butyl) thiophosphoric triamide (NBPT) on N metabolism, physiological and biochemical changes in the pineapple plant. At 4 month after planting (MAP), 1% urea (Urea) and 1% urea with NBPT (NLU) were applied. Data on urease enzyme activity, internal urea content, inorganic N [ammonium (NH4+) and nitrate (NO3−)], amino acids, total soluble protein, NBPT content, lipid peroxidase (MDA) activity, and electrolyte leakage were recorded for 10 days after treatment (DAT). The results indicated that the NBPT was taken up by the plant, thereby a clear inhibition of the urease activity was observed in pineapple leaf. A higher amount of urea content and a lower amount of NH4+ content in the leaf were the evidence of hydrolysis inhibition by NBPT. Consequently, the contents of amino acid and protein were diminished upon NBPT treatment which demonstrated a change in N metabolism. In addition, amino acid composition demonstrated that amide forms of amino acids were the major components of the decreased amino acid pool. In conclusion, lower MDA activity and electrolyte leakage were also observed under NBPT treated plants indicate that NBPT could release abiotic stress to some extent by protecting the cell wall from damage.

Comparative Study of Physicochemical Properties and Enzymatic Status of Imidacloprid Treated Soils from Various Zones of Haryana, India

Imidacloprid is the most commonly used insecticide in Haryana that play animportant role in pest management and hence improved crop yield production. This study was done to investigate the consequences of Imidacloprid on the activity of dehydrogenase and urease enzymes in soils of selected zones of Haryana. A 28 days experiment was carried out where sampling was done after 1st, 7th, 14th, 21st and 28th day of Imidacloprid application at different concentrations like T1 (1 mg/kg), T2 (2 mg/kg) and T3 (10 mg/kg). After analysing the physicochemical properties of soils of various zones the enzymatic activities were measured using colorimetric assays. Dehydrogenase activity was decreased initially after imidacloprid exposure but after 14 days a stimulation was observed in dehydrogenase activity at lower doses. The decrease was directly proportional to concentration of imidacloprid and indirectly proportional to time of incubation. Urease activity was inhibited by highest dose of imidacloprid after first day exposure. However, a stimulation in urease activity was observed after 14 days of imidacloprid treatment at all doses. Obtained results showed that the activity of dehydrogenase and urease were affected by concentration and treatment time of Imidacloprid significantly in soils of each selected zone of Haryana. The results provide a clue about the possible ecological effects of Imidacloprid.

Chemical fingerprints and bioactivities of 12 Anatolian Achillea species by LC-MS/MS with chemometric approach: Novel phytonutrients, natural food preservatives and chlorogenic acid sources

The objective of this study was to evaluate the biological activities and chemical fingerprint profiles of the extracts obtained from twelve Achillea L. species (A. lycaonica, A. biebersteinii (syn: A. arabica), A. kotschyi subsp. kotschyi, A. schischkinii, A. millefolium subsp. millefolium, A. sintenisii, A. setacea, A. teretifolia, A. wilhelmsii subsp. wilhelmsii (syn: A. santolinoides subsp. wilhelmsii), A. nobilis, A. goniocephala, A. spinulifolia). The antioxidant, enzyme inhibitory and cytotoxic effects were evaluated to investigate their bioactivity profiles. Furthermore, the total flavonoid and phenolic contents were determined and LC-MS/MS analysis was performed to reveal the phytochemical profile of the investigated extracts. A. kotschyi and A. nobilis species were detected to have very high antioxidant potential as well as high total phenolic content (260.00 ± 3.38 and 282.97 ± 3.14 ?g of PEs mg extract?1, respectively). According to the LC-MS/ MS results, A. kotschyi and A. nobilis species were found to contain very high concentrations of chlorogenic acid (55812.20 and 46407 ?g analyte g extract?1). Besides, the bioactivities and phenolic composition of these species were chemometrically analyzed using principal component analysis (PCA) and hierarchical clustering analysis (HCA) techniques. It has also been determined that Achillea species generally exhibit quite high cytotoxic activity against the HeLa cell line. The studied species showed high urease enzyme activities.

Elaeagnus angustifolia can improve salt-alkali soil and the health level of soil: Emphasizing the driving role of core microbial communities

Saline-alkali environments are widely distributed in China and significantly hinder the development of agriculture. This study characterizes the long-term effects of planting Elaeagnus angustifolia (E. angustifolia) on the physical and chemical properties, enzyme activities and microbial community characteristics of saline-alkali soil in the Songnen Plain (1, 2 and 3 years). The results showed that planting E. angustifolia reduced soil pH and electrical conductivity (EC) and increased soil total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (Nni), total potassium (TK), dissolved organic C (DOC), dissolved organic matter (DOM) and available potassium (AK) content and catalase, urease, polyphenol oxidase, phosphatase, sucrase and cellulase enzyme activities, and the results peaked in the 3 year. High-throughput sequencing showed that the bacterial abundance and diversity were as follows (from high to low) y3 > y2 > y1 > CK. E. angustifolia resulted in an increase in the relative abundance of the dominant bacteria. Proteobacteria and Pseudomonas were the major phylum and genus, respectively. Redundancy analysis showed that changes in the soil microbial community significantly affect the physical and chemical properties of the soil, with Proteobacteria members being the key microorganisms that reduce soil salinity. Network analysis showed that Pseudomonas (Proteobacteria) participated in the synthesis of key soil enzymes. 16S rRNA sequencing predicted that the expression of genes related to carbon (rbcL, acsA, acsB, Pcc and accA) and nitrogen (amoA/B, nxrA, hao, gdh, ureC and nosZ) transformation increased, and Pseudomonas members were key regulators of carbon and nitrogen dynamics. In conclusion, the planting of E. angustifolia could improve the physical and chemical properties of the soil by releasing root exudates into the soil and increasing the diversity and richness of soil microbial communities to improve saline-alkali soil, providing a theoretical basis for improving saline-alkali soil and promoting the sustainable development of modern agriculture.

Investigating the effect of microbial inoculants Frankia F1 on growth-promotion, rhizosphere soil physicochemical properties, and bacterial community of ginseng

Ginseng root rot caused by Fusarium solani (F. solani) is a highly destructive soil-borne disease that happens worldwide, which seriously affects the growth and development of many types of crops. Frankia casuarinae CcI3 (Frankia F1) microbial inoculants F1 on the mycelial integrity of pathogenic fungus F. solani, the growth of ginseng plants, and the structure of rhizosphere microbial community were carefully studied in the rhizosphere soil of ginseng infected with ginseng disease. Under the normal ginseng growth and F. solani infected environment, plant height, root length, dry weight, stem diameter, leaf area, and chlorophyll content increased by 40.57%, 68.98%, 92.09%, 56.67%, 23.29%, and 39.60% in T2 (50 mL microbial inoculants F1) compared with CK (natural control without treatment). Increased enzyme activity of phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), β-1, 3-glucanase, and chitinase showed improved disease resistance and stress resistance of plants in ginseng leaves having inoculation. Our present study demonstrated that the soil pH value, cation exchange capacity, organic matter, total nitrogen, available nitrogen, phosphorus, and potassium increased by 8.00%, 50.78%, 18.81%, 43.36%, 23.25%, 14.00%, and 5.11% in T2 compared with CK. Furthermore, the soil enzyme activities of catalase, sucrase, and urease in T2 treatment were increased by 12.14%, 27.56%, and 22.60%, respectively. Amplicon sequencing analysis revealed that the diversity of soil bacteria decreased after microbial inoculants F1 treatment. More specifically, the T2 treatment inhibited the growth of F. solani, and promoted that the relative abundance of Xanthomonadales, Sphingomonadales, Sphingobacteriales, Frankiales, and Propionibacteriales. The PICRUSt data predicted an array of bacterial functions, and microbial inoculants F1 primarily increased the abundance of functional genes related to bacterial metabolism in ginseng soil we confirmed. Collectively, we found that the optimal inoculation amount of Frankia F1 for inhibiting F. solani and promoting the growth of ginseng plants was 50 mL (T2), which could effectively regulate the soil microbial community structure during ginseng production. It helped to promote the sustainable development of Chinese agriculture.

Effect of High Hydrostatic Pressure Treatment on Urease Activity and Inhibition of Fishy Smell in Mackerel (Scomber japonicus) during Storage.

In this study, the physicochemical changes related to fishy smell were determined by storing high hydrostatic pressure (HHP)-treated mackerel (Scomber japonicus) meat in a refrigerator for 20 days. The inhibition of crude urease activity from Vibrio parahaemolyticus using HHP treatment was also investigated. The mackerel meat storage experiment demonstrated that production of trimethylamine (TMA) and volatile basic nitrogen (VBN), the main components of fishy smell, was significantly reduced on the 20th day of storage after the HHP treatment compared to the untreated mackerels. The results demonstrated that the increased ammonia nitrogen rates in the 2000, 3000, and 4000 bar, HHP-treated groups decreased by 23.8%, 23.8%, and 31.0%, respectively, compared to the untreated groups. The enzyme activity of crude urease was significantly reduced in the HHP-treated group compared to that in the untreated group. Measurement of the volatile organic compounds (VOCs) in mackerel meat during storage indicated that the content of ethanol, 2-butanone, 3-methylbutanal, and trans-2-pentenal, which are known to cause off-flavor due to spoilage, were significantly reduced by HHP treatment. Collectively, our results suggested that HHP treatment would be useful for inhibiting the activity of urease, thereby reducing the fishy smells from fish and shellfish.

Biochar amendment impacts on microbial community structures and biological and enzyme activities in a weathered tropical sandy loam

Microbial biomass and its activity influence soil quality to sustain crop productivity. A field experiment was conducted to investigate changes in soil microbial community structure, enzyme activities, and associated biological properties in response to biochar application in a tropical ecosystem. The treatments included control/no biochar (CT), 15-ton biochar ha−1 (BC-15), 30-ton biochar ha−1 (BC-30), and 30-ton corn cob biochar ha−1 + phosphate fertilizer (BC-30 + P). Biochar significantly increased microbial biomass C (by 4.5 to 8.2 folds) and N (by 1.4 to 2.7 folds), and mineralized C (by 1.2 to 1.7 folds). Incorporation of biochar at 30-ton ha−1 equally resulted in an efficient soil microbial activity by significantly decreasing specific maintenance respiration (qCO2) rates by 66 to 73%. Dehydrogenase and urease enzyme activities were increased by biochar amendments. Biochar treatments increased the abundance of arbuscular mycorrhiza (AMF) and soil fungi. However, only the BC-30 and BC-30 + P treated soils recorded increases in Gram-positive (G+) bacteria by 1.7 to 1.9 folds, and Gram-negative (G−) bacteria by 1.5 to 1.6 folds, respectively. For all functional groups of microbial communities, which included AMF, G+/G− bacteria, fungi, and actinobacteria, the highest concentration of total phospholipid fatty acid was observed when the soils were treated with 30-ton biochar ha−1. The most important soil factors that greatly contributed to the changes in microbial community composition were soil basal respiration, urease and dehydrogenase enzymes, microbial biomass carbon and nitrogen, metabolic quotient, and pH. The high fungal: bacteria in the soils treated with 30-ton biochar ha−1 implies that corn cob biochar amendment could increase C sequestration potential and enhance ecosystem stability in weathered tropical soils.

Nitrogen Fertilizers and Volatilization of Ammonia, Carbonic Gas Emissions and Urease Activity

ABSTRACT The large-scale use of fertilizers is an essential process for replacement fertilization, maintenance or correction of nutrient levels in tropical environments. Nitrogen stands out among the elements that plants need in greater quantity, and for this reason, nitrogen fertilizer is the most consumed, with an emphasis on urea. The urea [(NH2)2CO] can present high losses of ammonia (NH3), besides potentiating carbonic gas (CO2) emissions, especially in high temperatures. For this purpose, the objective of this work was to: (a) evaluate three temperature conditions (25, 35, 45°C) in N losses through NH3 volatilization, CO2 gas emissions, soil urease enzyme activity; (b) and evaluate the potential of N losses in conventional urea fertilizers and associated technology (urea with N-(n-butyl)thiophosphoric triamide (NBPT), polymer-sulfur coated urea). The application of conventional urea (CU) promoted volatilization losses of 30.19 mg dm−3, followed by urea with NBPT (UNBPT) (27.35 mg dm−3) and polymer-sulfur coated urea (UPS) (5.21 mg dm−3) from the application of 100 mg dm−3 in the soil. Fertilizers with associated technology were more efficient than CU, with emphasis on UPS. The highest values for NH3 volatilization were recorded at 45°C for CU (38.97 mg dm−3), followed by UNBPT (38.14 mg dm−3) and UPS (10.41 mg dm−3). It is concluded that, in general, volatilization losses of NH3 and gaseous emissions of CO2 followed the following order for the applied sources: UPS <CU and order: 25°C < 35°C < 45°C for the temperatures.

Biochar and Trichoderma aureoviride URM 5158 as alternatives for the management of cassava root rot

The root soil interface harbors complex microbial interactions that influence plant and soil health. A better understanding of using of biochar derived from different waste sources with Trichoderma spp. (TRI), and the relationship between plant disease and environmental parameters would assist setting priorities. Here, we hypothesized that biochar and TRI could be useful in managing cassava root rot, by mainly altering soil properties and their interactions. This hypothesis was tested by assessing the severity of plant disease and soil parameters using biochar derived from four sources (coffee grounds-CG, coffee husks-CH, bean husks-BH, and soursop residue-SW). Our analysis revealed that all TRI-inoculated biochar applied to the soil decreased cassava root rot severity, which was attributed to changes in soil parameters such as pH, P, K, and total organic carbon. Additionally, SW + TRI reduced the severity in shoots by 75% and increased beta-glucosidase (109%) and urease (200%) enzyme activities, thereby reducing cassava root rot severity, which contributed to plant growth and improved soil; hence, this biochar can be recommended in controlling this disease. Overall, our findings expand our knowledge about the reuse of wastes transformed into biochar, which could serve as an alternative tool for plant disease management and provide important information to develop strategies that can be incorporated in the global health concept.