Egyptian Soil Research Articles

Efficacy of Egyptian Parasitic Nematodes, Heterorhabditis bacteriophora (BA1) and Steinernema carpocapsae (BA2) in Bio-control of Economically Important Pests

Background: Entomopathogenic nematodes (EPNs) are obligate lethal parasites of insects and are globally used as safe biocontrol agents against a wide range of insect pests. They occur in most agricultural soils all around the world. The insecticidal activity of two native EPNs Heterorhabditis bacteriophora (BA1) and Steinernema carpocapsae (BA2), isolated from the Egyptian soil was examined against eight different economic insect pests under laboratory conditions. These pests are the Greater wax moth larvae, Galleria mellonella; the cotton leafworm, Spodoptera littorallis; the cutworm, Agrotis ipsilon; the european corn borer, Osterinia nubilalis; the greater sugarcane borer, Sesamia critica; the apple tree borer, Zeuzera pyrina; the sugar beet fly, Pegomyia mixta and the tortoise beetle Cassida vittatta. Three nematode concentrations (100, 50, and 25 /ml water) of infective juveniles (IJs) were applied per insect. The test was conducted at 25± 2 °C and about 70± 2 % RH. Results: The median lethal concentration (LC50) of H. bacteriophora BA1– was almost– higher than that of S. capocapsae BA2 against the different tested insect pest larvae. The percentage of the cumulative mortality ranged between 46 and 100% in general, according to the tested concentration and/or the nematode species. The comparison between the mortality percentages caused by BA1 and BA2 nematodes to differently treated insect larvae revealed that BA1 was almost more virulent than BA2. Results showed that the lowest LC50 value was found to be 2.15 IJs, for H. bacteriophora BA1 isolate. Conclusions: The results showed that both indigenous EPNs isolates had a good impact in the management of the eight economic insect pests tested in this study had insecticidal properties and could be positively enrolled in integrated pest management programs against different insect pests.

Evaluation of Some Soil Tests to Extract Many of The Available Micronutrients in The Egyptian Soils

Three extractions were used to assess the availability of micronutrients in different soil collections. The suitability of some extractions under the conditions of Egyptian soils will be discussed. Three extraction methods (Mehlic 3, Soltanpour and Kelowna) were used for the determination of available Fe, Zn, Mn, Cu and B content of the soil samples (sand,calcareous and clay) during 2020 season. Surface soil samples (0-30 cm) were collected from three sites of Al Boston area in the new Nobaria, Governorate, Egypt, during 2020 season. From each selected plot, ten points were selected in a zig-zag path. The results revealed that the highest values of available Fe, Zn and Cu were given with the extraction solution of Soltanpour, while the highest values of available Mn and B were given with the extraction solution of Mehlic 3. On the other hand, the results showed that clay soil recorded the maximum available Fe, Zn, Mn and Cu, while calcareous soil recorded the maximum available boron content. The interaction between different extraction methods and soil samples was highly significant during 2020 season.

Bacillus niabensis OAB2: Outstanding bio-factory of selenium nanoparticles

Selenium is an essential trace element, but its oxyanions, selenite [SeO32−] or selenate [SeO42−], are ecologically toxic. Different microorganisms were reported to transform the soluble toxic selenite or selenate to the insoluble less toxic elemental selenium (Se0), forming selenium nanoparticles (SeNPs). In the present study, we isolated a selenate-reducing bacterial strain from Egyptian soil that showed remarkable tolerance for elevated sodium selenate concentration (40 mM). The treatment of the bacterial cells with 1 kGy gamma irradiation attained an extra ~10% SeNPs yield throughout 72 h. Furthermore, the irradiation improved the selenate reduction rate where almost half of the anions were reduced at the first 28 h of the incubation period, versus about 44 h by the control cells. The UV–Vis spectra of the SeNPs generated by the irradiated and non-irradiated cultures showed distinct variation. The XRD and Raman spectroscopy of the two generated nanoparticles proved the irradiation influence on the crystalline structures of the SeNPs. The FESEM, EDX, TEM, and DLS revealed that gamma irradiation has a serious impact on the size, shape, and composition of the generated SeNPs. Zeta potential showed that both generated SeNPs had negative charges but with different values, while FTIR inspection exhibited similar profiles for both types of SeNPs.Both the control and irradiated SeNPs exhibited diversified antimicrobial impact, which markedly peaked against Gram-positive test organisms with values greater than the antimicrobial test control. The cytotoxicity of the synthesized SeNPs versus the WI38 cell line and antiviral activities against adenovirus-9 were also inspected.

Partial characterization of levan polymer from Pseudomonas fluorescens with significant cytotoxic and antioxidant activity.

Microbial levan has great potential as a functional biopolymer in different fields including foods, feeds, cosmetics, and the pharmaceutical and chemical industries. In this study, a good levan producer bacterial strain of Pseudomonas fluorescens strain ES, isolated from soil in Egypt in a previous study, was used. Levan production by this strain was optimized using Plackett-Burman experimental design (PBD) to screen the critical factors of several process variables and Centered Central Composite Design (CCD) was applied for further estimation of the relationship between the variables and the response as well as optimization of the levels. Plackett-Burman (P-B) design showed a p-value 0.0144 less than 0.05 indicated the significance of the model. Sucrose, potassium dihydrogen phosphate, yeast extract and pH value showed the most significant effect on levan concentration at the values of 89.17, 65.83, 24.17, and 15.83, respectively. The purified levan polymer was characterized using different Physico-chemical methods such as Fourier Transform Infrared Spectrometer (FTIR), Nuclear magnetic resonance (NMR), and High-Performance Liquid Chromatography (HPLC) to determine the main composition and functional groups in the obtained polymer. HPLC results indicated that the polymer purification increased the percentage of fructose residue from 75 up to 89. Furthermore, 1H and 13C NMR spectroscopy analysis showed great matching between the obtained signal for our polymer with that reported in other people’s work. The obtained levan polymer exhibited cytotoxic activity against Human epidermoid Skin carcinoma and Hepatocellular carcinoma with IC50 of 469 and 222.7 µg/ml, respectively. Antioxidant activity was determined using DPPH assay and the percentage of inhibition at 1000 µg/ml was found to be <50 (13.89 ± 1.07) with IC50 of (24.42 ± 0.87).

Corn Cob-Derived Biochar Improves the Growth of Saline-Irrigated Quinoa in Different Orders of Egyptian Soils

Biochar is one of the important recycling methods in sustainable development, as it ensures the transformation of agricultural wastes into fertilizers and conditioners that improve soil properties and fertility. In the current study, corn cob-derived biochar (CB) was used to reduce the negative effects of saline water on quinoa (Chenopodium quinoa cv. Utosaya Q37) grown on Aridisols and Entisols, which are the major soil groups of Egyptian soils. Quinoa plants were cultivated in pot experiment and were irrigated with saline water (EC = 10 dS m−1). The experiment contained three treatments, including control without any treatment, biochar at a rate of 1% (w/w) (BC1), and biochar at a rate of 3% (w/w) (BC3). The findings of the current study showed that BC treatments realized significant effects on soil salinity, pH, soil organic matter (SOM), and plant availability and nutrients’ uptake in the two soils types. BC3 increased the SOM in Entisols and Aridisols by 23 and 44%; moreover, the dry biomass of quinoa plants was ameliorated by 81 and 41%, respectively, compared with the control. Addition of biochar to soil increased the nutrients’ use efficiencies by quinoa plants for the two studied Egyptian soils. Biochar addition caused significant increases in the use efficiency of nitrogen (NUF), phosphorus (PUE), and potassium (KUE) by quinoa plants. BC3 increased NUE, PUE, and KUS by 81, 81, and 80% for Entisols, while these increases were 40, 41, and 42% in the case of Aridisols. Based on the obtained results, the application of corn cob biochar improves the soil quality and alleviates the negative effects of saline irrigation on quinoa plants grown on Aridisols and Entisols Egyptian soils. Biochar can be used as a soil amendment in arid and semi-arid regions to reduce the salinity hazards.

Inoculation and colonization of isolated entomopathogenic fungi Beauveria bassiana in rice plants, Oryza sativa L. through seed immersion method

BackgroundThe aims of the present study were to isolate and identify native entomopathogenic fungi, Beauveria bassiana from the Egyptian soil and to evaluate the artificial establishment of B. bassiana as endophytes in rice plants through seeds immersion.ResultsTen soil samples were collected from different cultivated fields at the Ismailia Governorate. Only one sample was positive with a ratio of 10%. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolate obtained from the soil sample belongs to B. bassiana and was registered under the accession no. MN337282. To test the endophytic colonization of B. bassiana, rice seeds were soaked by B. bassiana with a concentration of 5 × 107 spores/ml, to test when B. bassiana become an endophyte in rice plants. The plants were examined for endophytic presence of B. bassiana, 30 days post treatment. PCR amplification using fungal specific primers for a conserved region of β-tubulin gene yielded identical 360 bp products from both B. bassiana and rice treated plants.ConclusionThe results showed that seeds immersion with a conidial suspension proved to be a good method to introduce B. bassiana into rice leaves to protect the rice plants against stem borers.

Field and modelling study for deficit irrigation strategy on roots volume and water productivity of wheat

In many regions of the world, including Egypt, water shortages threaten food production. An irrigation deficient strategy in dry areas has been widely investigated as a valuable and sustainable approach to production. In this study, the dry matter and grain yield of wheat was decreased by reducing the amount of irrigation water as well as the volume of the root system. As a result of this, there was an increase the soil moisture stress. This negatively affected the absorption of water and nutrients in the root zone of wheat plants, which ultimately had an effect on the dry matter and grain yield of wheat. The values of dry matter and grain yield of wheat increased with the ʻSakha 94ʼ variety compared to the ʻSakha 93ʼ class. It is possible that this was due to the increase in the genetic characteristic of the root size with the ʻSakha 94ʼ variety compared to the ʻSakha 93ʼ class, as this increase led to the absorption of water and nutrients from a larger volume of root spread. Despite being able to increase the water productivity of wheat by decreasing the amount of added irrigation water, the two highest grain yield values were achieved when adding 100% and 80% of irrigation requirements ( IR) needed to irrigate the wheat and no signif-icant differences between the yield values at 100% and 80% of IR were found. Therefore, in accordance with this study, the recommended irrigation for wheat is at 80% IR which will provide 20% IR. When comparing the water productivity of two wheat varieties in study, it becomes clear that ʻSakha 94ʼ was superior to ʻSakha 93ʼ when adding the same amount of irrigation water, and this resulted in increased wheat productivity for ʻSakha 94ʼ. The SALTMED results confirmed good accuracy (R2: 0.92 to 0.98) in simulating soil moisture, roots volume, water application efficiency, dry matter, and grain yield for two varieties of wheat under deficit irrigation conditions. Whilst using sprinkler irrigation system under sandy soils in Egypt.

Identification of pollution sources in roadside soils of Cairo-Alexandria Highway, Egypt

Nile Delta represents 63% of Egypt’s fertile agricultural land. Unfortunately, food chain contamination with potentially toxic elements (PTEs) was recorded along Cairo- Alexandria Highway within Nile Delta. This paper aims to identify pollution sources of PTEs (Cd, Pb, Co, Ni, Zn, Cu, Cr, and Mn), using multivariate statistics. Generally, the studied soil is alkaline loam with about 3.69% CaCO3 and 1.97% organic matter. Pollution levels varied widely from uncontaminated to highly contaminated soil. Cd, Pb, Co, and Ni showed spatial variability, relatively high enrichment, reflecting their anthropogenic sources. Mn and Cr show more uniform distribution, reflecting their natural source from the geologic parent material of Egyptian soil. Surprisingly, no significant road traffic impact was observed at the sampling sites. Multivariate analysis indicates P-fertilizer is the main pollution source rather than traffic in roadside soils. The prevailing of fertilizers as a pollution source may be referred to the expansion in the use of unleaded fuel and the continuous increase in the annual fertilization rate.

Isolation, identification, and study of the genetic diversity between three entomopathogenic nematodes belonging to Heterorhabditis sp. using ISSR technique

BackgroundEntomopathogenic nematodes (EPNs) are widely used in biological control for soil-dwelling stages of many insect pests that are characterized by their safety to most non-target organisms and to the environment.ResultsThe objectives of the present study were isolation of EPNs from agricultural soil in Egypt for further use in biological control programs and study the genetic variation among them using the molecular marker inter-simple sequence repeats (ISSR). Three out of 25 soil samples collected from fields cultivated with strawberry, tangerine, and pumpkin were positive for the presence of EPNs, using the Galleria baiting technique. Sequencing of the internal transcribed spacer (ITS) region indicated that the isolates obtained belong to Heterorhabditis sp. The ITS sequences were submitted to the National Center for Biotechnology Information (NCBI) and registered under accession nos. MH553165, MH553168, and MH553169. Six ISSR primers were used. The numbers of polymorphic bands were 42 out of 56, and the polymorphism percentage was 75%. The highest number of bands was 12 bands generated by primer ISSR8 followed by UBC-809 (11 bands) while recorded the lowest band number (4 bands), the percentage of polymorphism ranged from 40% (ISSR1) to 100% (ISSR6).ConclusionISSR marker can be considered a good marker to study genetic diversity and detecting the genetic polymorphism among the nematodes species.

Bioprocess development for enhanced endoglucanase production by newly isolated bacteria, purification, characterization and in-vitro efficacy as anti-biofilm of Pseudomonas aeruginosa

Endoglucanase producing bacteria were isolated from Egyptian soils and the most active bacterial strain was identified as Bacillus subtilis strain Fatma/1. Plackett–Burman statistical design was carried out to assess the effect of seven process variables on endoglucanase production. Carboxymethyl cellulose (CMC), yeast extract and peptone were the most significant variables that enhanced the endoglucanase production and thus were selected for further optimization using face-centered central composite design. The highest yield of endoglucanase (32.37 U/mL) was obtained in run no. 9, using 18 g/L CMC, 8 g/L peptone, 7 g/L yeast extract and 0.1 g/L FeSO4.7H2O. The optimized medium showed about eightfold increase in endoglucanase production compared to the unoptimized medium. The produced crude enzyme was further purified by ammonium sulfate precipitation, then DEAE-Sepharose CL6B column. The purified enzyme was shown to have a molecular weight of 37 kDa. The enzyme showed maximum activity at pH 8.0, temperature of 50 °C, incubation time of 60 min. The half-life time (T1/2) was 139.53 min at 50 °C, while being 82.67 min at 60 °C. Endoglucanase at concentration of 12 U/mL effectively removed 84.61% of biofilm matrix of Pseudomonas aeruginosa with marked reduction in carbohydrate content of the biofilm from 63.4 to 7.9 μg.

Guideline references to levels of heavy metals in arable soils in upper Egypt

Four soil profiles were selected from four different locations in upper Egypt including Tushka, Wadi El-Nuqra, El-Kharga, and El-Dakhla to evaluate the total and dithionate-citrate-bicarbonate (DCB) extractable heavy metals (Fe, Mn, Zn, Cu, Pb, Cr and Ni) levels in these soils. The heavy metal distributions in bulk soil samples and their size fractions (clay, silt and very fine sand) were also investigated. The studied soils had a coarse texture in all locations with mildly to moderately alkaline, slightly saline and low contents of calcium carbonate and organic matter. Clay and silt fractions of these soils showed the highest total and DCB-extractable levels of these metals; whereas the very fine sand fraction contained the lowest. In comparison with the average levels of heavy metals in the world soils, the studied soils displayed levels of heavy metals within the range or less than those of world soils. A moderate or moderately severe enrichment factor (EF) values were recorded in Tushka, El-Kharga and El-Dakhla soils for Pb and moderate EF ones for Zn were found in Tushka and El-Kharga ones. On the contrary, the values of EF for other heavy metals such as Mn, Cu, Cr, and Ni at most locations were <2, showing deficient to minimal enrichment in the soils. However, the calculated contamination factor (Cf) and geo-accumulation index (Igeo) indicated that the soil samples are characterized by uncontaminated levels of all heavy metals (Igeo of < 0). Positive correlations among the total Fe, Mn, Cu and Ni suggest that these metals may be originated from the same source, mainly from a lithogenic origin. The contents of soil heavy metals in all locations were less than the globally allowable concentrations, which indicate no harmful effect of these metals. Therefore, the contents of these heavy metals can be taken as a guide reference to the levels of the heavy metals in uncontaminated Egyptian soils.

Genetic variability among three Egyptian isolates of Heterorhabditis indica using a new marker technique (SCoT)

BackgroundEntomopathogenic nematodes (EPNs) are a group of nematode families, have the ability to search for their hosts, and are considered as promising biological control candidates for insect pests, providing protection to non-target organisms and the environment.ResultsThis study was conducted to isolate indigenous EPN isolates from Egyptian agricultural soils for further use in biological control programs and study their genetic polymorphism among the previously isolated isolates under accession no. MH553167 and MK300683 and the new isolate (MH496627), using the start codon targeted (SCoT) marker. One out of 15 soil samples obtained from a banana cultivated field was positive for the presence of EPNs, using the Galleria baiting method. Morphological analysis and sequencing of the internal transcribed spacer (ITS) region suggested that the isolate obtained belongs to Heterorhabditis indica. The sequence of the ITS was submitted to the National Center for Biotechnology Information (NCBI) and registered under accession no. MH496627. Ten SCoT primers were used in the study; the polymorphic bands were 68 out of 76 with 89% as polymorphism percentage. The highest numbers of bands were 10 bands generated by SCoT 1 and SCoT 18 while SCoT 48 and SCoT 60 recorded the lowest band number (5 bands).ConclusionsThe present study is considered as a preliminary study to demonstrate the effectiveness of the SCoT marker for the first time in assessing genetic relationships in EPNs.

Stabilization Characteristics of Different Loose Sandy Soils using Microbial-Induced Calcite Precipitation

Loose sands (siliceous, silty, and calcareous classes) are extensively found near arid areas in Egypt. Furthermore, many geotechnical structures, like water channels and roads, may be constructed on weak or loose sand soils. The geotechnical behavior of loose sands is usually connected with different interdependent problems, such as high permeability, low shear strength, low bearing capacity, high seepage, and low stability. This work characterized the effect of stabilization of the siliceous, silty, and calcareous sandy soils via biocementation process using Sporosarcina pasteurii bacteria as a potential eco, commercial, and engineering solution. This was carried out using bacteria, fixation, and cementation solutions (BFC) at different times number additions. The results indicated that the addition times of solution have a remarkable effect on the physical and mechanical properties of sandy soils. The results also proved that the precipitation of calcite by the bacterial activity led to cohesion of soil grains, and this increased the resistance of soils to deterioration. In addition, the high content of the precipitated calcium carbonate enhanced the shear strength and the unconfined compressive strength and decreased the soil permeability. S. pasteurii bacteria can be used successfully and commercially in the biocementation process for siliceous sand, silty sand, and calcareous sandy soils in Egypt using the recommended conditions and mixes.

Degradation Kinetics and Half-Lives of Fenitrothion and Thiobencarb in The New Reclaimed Calcareous Soil of Egypt Using GC-MS

The degradation process of pesticides is one of the mechanisms for losing sush chemical from the soil after application. The persistence, degradation kinetics and half-lives of fenitrothion (insecticide) and thiobencarb (herbicide) in the new reclaimed calcareous soil in Egypt were studied under laboratory conditions. The recovery percentages of fenitrothion and thiobencarb were 89.67 and 88.34%, respectively. The results of degradation kinetics showed that residues of fenitrothion and thiobencarb were rapidly decreased during the first five days after treatment. Residues of fenitrothion and thiobencarb remained on the second day were 72.45% and 57.63%, while on the fifth day were 37.72 and 47.18%, respectively. Both tested pesticides disappeared very rapidly from the soil following a bi-phasic pattern. According to the graphical and integral methods, the fit model to describe the degradation kinetic of fenitrothion and thiobencarb is the first order model. The rate constant (k) values for degradation of the two pesticides were 0.036 and 0.068 for fenitrothion and thiobencarb, respectively. The estimated values of half-life were 19.36 days for fenitrothion and 10.24 days for thiobencarb. In general, thiobencarb degraded in sandy clay loam soil about twice faster than fenitrothion.

Indole Derivatives Obtained from Egyptian Enterobacter sp. Soil Isolates Exhibit Antivirulence Activities against Uropathogenic Proteus mirabilis.

Proteus mirabilis is a frequent cause of catheter associated urinary tract infections (CAUTIs). Several virulence factors contribute to its pathogenesis, but swarming motility, biofilm formation, and urease activity are considered the hallmarks. The increased prevalence in antibiotic resistance among uropathogens is alarming and requires searching for new treatment alternatives. With this in mind, our study aims to investigate antivirulence activity of indole derivatives against multidrug resistant P. mirabilis isolates. Ethyl acetate (EtOAc) extracts from Enterobacter sp. (rhizobacterium), isolated from Egyptian soil samples were tested for their ability to antagonize the virulence capacity and biofilm activity of P. mirabilis uropathogens. Extracts of two Enterobacter sp. isolates (coded Zch127 and Cbg70) showed the highest antivirulence activities against P. mirabilis. The two promising rhizobacteria Zch127 and Cbg70 were isolated from soil surrounding: Cucurbita pepo (Zucchini) and Brassica oleracea var. capitata L. (Cabbage), respectively. Sub-minimum inhibitory concentrations (Sub-MICs) of the two extracts showed potent antibiofilm activity with significant biofilm reduction of ten P. mirabilis clinical isolates (p-value < 0.05) in a dose-dependent manner. Interestingly, the Zch127 extract showed anti-urease, anti-swarming and anti-swimming activity against the tested strains. Indole derivatives identified represented key components of indole pyruvate, indole acetamide pathways; involved in the synthesis of indole acetic acid. Additional compounds for indole acetonitrile pathway were detected in the Zch127 extract which showed higher antivirulence activity. Accordingly, the findings of the current study model the feasibility of using these extracts as promising antivirulence agent against the P. mirabilis uropathogens and as potential therapy for treatment of urinary tract infections (UTIs).

Chemical Fractionation and Risk Assessment of Some Heavy Metals in Soils, Assiut Governorate, Egypt

Toxic elements behavior in Egyptian soil need more studies for the enhancement of soil quality and human health protection. The current study focuses on the mobility assessment of chemical species of As, Pb, Cr, Ni, Cu and Co in soils due to anthropogenic emission using sequential extraction (SE) and risk assessment code (RAC). Generally, the studied soils are alkaline calcareous loam soil. It has a low organic matter (OM) that ranges from 1 to 3.8% and is enriched with As, Pb, Cr, Ni, Cu and Co, which preferentially accumulate in soil clay and silt fraction. SE revealed that the non-residual (bioaccessible) fraction contains about (70.7%) As, (65.2%) Co, (58.8%) Cr, (28.4%) Cu, (6.8%) Ni and (64.5%) Pb, indicates the risk of pollution with As, Co, Cr, and Pb. RAC values indicated a high risk of soil pollution with As, medium risk of Co and Pb, low risk of Cu and Ni, and no risk of Cr. The results pointed out the geogenic source of Cr, mixed source of Co, Cu, and Ni and the anthropogenic source of As and Pb. The spatial distribution analyses of these metals indicated the role of urbanization, traffic, and industry on the releasing of toxic metals into the environment.

THE ROLE OF ORGANIC FERTILIZATION IN RAISING POTATO PRODUCTIVE EFFICIENCY AND WATER PRODUCTIVITY UNDER THE CONDITIONS OF ORGANICALLY POOR SANDY SOIL

Water application efficiency, soil organic matter content, water stress inside root zone, EC soil, yield, quality and water productivity of potato were investigated under arid and poor sandy soils in Egypt during two growing seasons 2018/2019 and 2019/2020 at the Research Farm of National Research Center (NRC). Water application efficiency and the average of soil organic matter content were increased by increasing the amount of organic fertilizers applied. The values of the yield of potato and protein content and carbohydrates content were increased by increasing the amount of organic N-fertilizers applied up to 50% and it decreased with the continued increase in organic N-fertilizers addition. The values of the yield of potato were increased by increasing the amount of organic N-fertilizers applied up to 50% and it decreased with the continued increase in organic N-fertilizers addition. There are a set of positive effects resulted from the increase in the addition of N-organic fertilizers against one negative effect. The increase in the addition of organic N-fertilization led to an increase in the organic matter and thus increased the water application efficiency, thus a decrease in water stress and a decrease in the accumulation and concentration of salts in the area of root proliferation until reaching the best proportion of organic N-fertilization when adding 50% with 50% of mineral nitrogen fertilization, while the productivity decreased when continuing with the percentage of addition of organic N-fertilization until reaching the lowest values of productivity when organic N-fertilization is 100% where, the total percentage of nitrogen available (NO3) in the area of root proliferation decreased after the percentage of organic fertilization exceeded 50% and the negative effect of nitrogen fertilization stress on the decrease in potato productivity. Finally, the results of the study concluded that, the necessity of relying on organic nitrogen fertilization in addition to mineral nitrogen fertilization at 50% organic to 50% mineral without any significant impact on the productivity and quality characteristics of potato under arid and sandy soils conditions in Egypt.

Isolation and optimized production of putative antimicrobial compounds from Egyptian soil isolate Streptomyces sp. MS. 10

BackgroundThe rapid spread of antibiotic resistance has increased research interest in the discovery of natural products, mainly from actinomycetes, which have been the primary source of antimicrobial compounds. This study aimed to isolate, characterize, and optimize the production of some of the bioactive compounds from bioactive soil actinomycetes.ResultsOne promising soil actinomycete, which was molecularly identified as Streptomyces sp. and designated as Streptomyces sp. MS. 10, showed broad-spectrum antimicrobial activity, including activity against methicillin-resistant Staphylococcus aureus. Thus, it was selected for isolation of its major bioactive compounds. Polymerase chain reaction amplification of the genes responsible for antibiotic biosynthesis showed the presence of genes encoding type I and type II polyketide synthase. Liquid chromatography-mass spectrometry analysis found that the major antimicrobial compounds produced by Streptomyces sp. MS. 10 were weakly ionized bioactive secondary metabolites. A large-scale fermentation experiment of Streptomyces sp. MS. 10 using pre-optimized culture conditions followed by bioassay-guided chromatographic separation of its secondary metabolites resulted in the isolation of putative bioactive compounds that were identified as fatty acids using proton nuclear magnetic resonance spectroscopy.ConclusionsEgyptian soil is still a good source for exploring bioactive actinomycetes. Additionally, this study highlighted the importance of combining both physicochemical and genotypic characterization with spectroscopic analysis of the major natural products when isolating bioactive metabolites.

Measuring the engineering properties of landfill leachate-contaminated soil in Egypt

Industrial activities produce millions of tons of hazardous waste annually, which are eventually disposed of in landfills. In this study, the effect of saline industrial hazardous landfill leachate (SIHLL) on the geotechnical properties of natural and contaminated silty clay soil was investigated via laboratory-based experiments in order to assess the potential application of this soil as a barrier lining in a saline hazardous industrial waste landfill. Contaminated soil specimens were prepared by mixing natural soil with SIHLL at different concentrations (0%, 25%, 50%, 75%, and 100%). The results revealed that the permeability coefficient (k) and the total pore volume (TPV) of the SIHLL-contaminated soil decreased from 8.6 × 10−8 to 5.91 × 10−8 cm/s and from 10.24 × 10−2 to 7.65 × 10−2 cm3/g, respectively, as the SIHLL concentration was increased from 0 to 50%. These effects were mainly due to the high concentration of salts in the SIHLL. The addition of SIHLL reduced the optimum moisture content (OMC) of the soil from 18% for natural soil to 14% for 100% SIHLL-contaminated soil, and the maximum dry density (MDD) recorded (for 100% SIHLL-contaminated soil) was 17.95 kN/m3. The angle of internal friction (φ) of the soil dropped from 27.8° for 0% SIHLL-contaminated soil to 23.7° for 100% SIHLL-contaminated soil. Also, the cohesion (c) decreased as the SIHLL concentration increased. In addition, considerable lowering of the consistency limits was observed for the SIHLL-contaminated soils. Based on these findings, the studied silty clay soil would be suitable for use in the construction of a new hazardous solid-waste landfill liner due to its low permeability and widespread availability in Egypt.

IMPROVING SOME IRRIGATION EFFICIENCYS, SOIL FERTILITY, YIELD AND QUALITY OF WHEAT UNDER DEFICIT IRRIGATION BY INTEGRATED N-FERTILIZATION

One of the most agricultural strategiesis improving irrigation and fertilization. Two field experiment were conducted for study the effect of deficit irrigation strategy and integrated N-fertilization on the water application efficiencies, soil organic matter content, soil electrical conductivity, yield and quality of wheat were investigated under arid and sandy soils in Egypt and field experiments were conducted during 2018/2019 and 2019/2020 at the Research Farm of National Research Center (NRC). Water application efficiency and the average of soil organic matter content were increased by increasing the amount of organic fertilizers applied and decreased by increasing the volume of applied water but the average of electrical conductivity of soil were decreased by increasing the amount of organic fertilizers applied and increasing the volume of applied water. The values of the grain yield “GYwheat” and protein content “PCwheat“and carbohydrates content “CCwheat” were increased by increasing the amount of organic N-fertilizers applied up to 50% and they decreased with the continued increase in organic N-fertilizers addition. Although most of the characteristics, especially crop yield, decrease with the decrease in the amount of added irrigation water, in this study there were no significant differences when irrigation with 100% or 80% of full irrigation( FI), so a decrease of 80% of FI may not have resulted in any effect on the moisture stress, on the contrary, most of the studied characteristics were slightly higher when irrigation by 80% FI than full irrigation. In spite of the highest values of the water productivity of the wheat crop, it was at irrigation with 60% of the total irrigation, but there were high significant differences in the values of the higher productivity when irrigation with 80% of FI with adding 50% organic N-fertilizers with 50% mineral N-fertilizers. Finally, the results of the study concluded that, the necessity of relying on organic nitrogen fertilization in addition to mineral nitrogen fertilization at 50% organic to 50% mineral in addition to the possibility of irrigation at 80% of full irrigation, i.e. saving 20% of irrigation water without any significant impact on the productivity and quality characteristics of wheat under arid and sandy soils conditions in Egypt.