Search Results (14)

A simple and rapid precipitation process was successfully employed to prepare silver phosphate (SP, Ag₃PO₄). Two different phosphate sources: diammonium hydrogen phosphate ((NH₄)₂HPO₄) and dipotassium hydrogen phosphate (K₂HPO₄) were applied separately as the precursor, obtaining ((NH₄)₂HPO₄)⁻ and K₂HPO₄⁻ derived SP powders, named SP-A or SP-P, respectively. Fourier transform infrared (FTIR) spectra pointed out the vibrational characteristics of P–O and O–P–O interactions, confirming the presence of the PO43– functional group for SP. X-ray diffraction (XRD) patterns revealed that the SP crystallized in a cubic crystal structure. Whereas the field emission scanning electron microscope (FESEM) exposed spherical SP particles. The potentially antibacterial activity of SP-A and SP-P against bacterial Bacillus stratosphericus, yeast Meyerozyma guilliermondii, and fungal Phanerodontia chrysosporium was subsequently investigated. All studied microorganisms were recovered and isolated from the aquatic plant during the tissue culture process. The preliminary result of the antimicrobial test revealed that SP-A has higher antimicrobial activity than SP-P. The superior antimicrobial efficiency of SP-A compared to SP-P may be attributed to its purity and crystallite size, which provide a higher surface area and more active sites. In addition, the presence of potassium-related impurities in SP-P could have negatively affected its antimicrobial performance. These findings suggest that SP holds potential as an antimicrobial agent for maintaining sterility in tissue cultures, particularly in aquatic plant systems. The growth of both B. stratosphericus and M. guilliermondii was suppressed effectively at 30 ppm SP-A, whereas 10 ppm of SP-A can suppress P. chrysosporium development. This present work also highlights the potential of SP at very low concentrations (10–30 ppm) for utilization as an effective antimicrobial agent in tissue culture, compared to a commercial antimicrobial agent, viz., acetic acid, at the same concentration. Full article

Sugar Belle^® mandarin is considered tolerant to Huanglongbing (HLB); however, recent reports have raised concerns about its fruit quality, noting issues such as reduced fruit size, thin peel, poor coloration, decreased firmness, and suboptimal juice quality. Two-year field experiments were conducted to improve external and internal fruit characteristics through foliar application of potassium (K) in five-year-old Sugar Belle mandarin grown in Florida sandy soil. The experiment consisted of foliar K supply (17 kg/ha) via Potassium Nitrate (PN, 4.7 kg/ha N), Dipotassium Phosphate (DKP, 12.7 kg/ha P₂O₅), PN with boron (PNB, 0.84 kg/ha B) at different application times (May, July, September), including one-time Gibberellic acid spray (GA@10 mg/L) and control treatments. PN application during July (PN_J) or two applications of PN with B during May and July (PNB_MJ) resulted in a larger fruit size (>65 mm). Results showed that PN application before fall (May or July) resulted in a significantly thicker peel (2.3 mm), 1.15 fold more than the control and GA treatment. Fruit puncture resistance force was significantly higher (33.1 N) with GA treatment (p = 0.07), followed by PNB_MJ (32.6 N). Meanwhile, K spray positively influenced juice qualities and peel color, regardless of application time or source. However, GA treatment significantly reduced juice quality and peel color. These findings highlighted the benefits of foliar K supply as PN to improve fruit qualities in HLB-affected citrus grown in sandy soil. Full article

Novel dentin bonding pretreatment using copper sulfate (CuSO₄) and dipotassium hydrogen phosphate (K₂HPO₄) may create a more hydrophobic environment for dentin bonding. Thus, this study aims to investigate the impact of a CuSO₄ + K₂HPO₄ pretreatment on dentin μTBS when bonded with a universal adhesive to conventional and CAD/CAM resin composites. Eighty recently extracted human molars (n = 80) were chosen and placed in transparent acrylic blocks to expose the crowns entirely. Nano-filled resin composite and CAD/CAM resin blocks were selected. Based on the dentin pretreatment, type of resin composite, and adhesion strategy, the teeth were randomly allocated into eight equal groups (n = 10). The microtensile bond strength (μTBS) and fracture mode were determined. A three-way analysis of variance (ANOVA) was used to analyze the μTBS data, followed by Tukey’s post hoc test. The μTBS values were not significantly affected by either the resin composite type (p > 0.05) or the adhesive strategy (p > 0.05) according to the three-way ANOVA results. Conversely, significant differences were detected between no dentin pretreatment (24.20 ± 4.54 MPa) and CuSO₄ + K₂HPO₄ pretreatment (33.66 ± 5.22 MPa) using an etch-and-rinse adhesive strategy for nano-filled composites (p < 0.001). Additionally, significant differences were detected between no dentin pretreatment (24.71 ± 4.33 MPa) and CuSO₄ + K₂HPO₄ pretreatment (32.49 ± 4.92 MPa) using an etch-and-rinse adhesive strategy for CAD/CAM resin blocks (p < 0.001). Moreover, significant differences were detected between no dentin pretreatment (21.20 ± 3.40 MPa) and CuSO₄ + K₂HPO₄ pretreatment (30.31 ± 3.87 MPa) using a self-etching adhesive strategy for nano-filled composites (p < 0.001). Also, significant differences were detected between no dentin pretreatment (23.89 ± 3.89 MPa) and CuSO₄ + K₂HPO₄ pretreatment (31.22 ± 4.71 MPa) using a self-etching adhesive strategy for CAD/CAM resin blocks (p < 0.001). In conclusion, dentin μTBS was enhanced by a copper-based treatment when used with nano-filled and CAD/CAM resin blocks. Full article

Paenibacillus polymyxa strain PJH16, isolated and tested by our team, suppresses cucumber Fusarium wilt as an efficient biocontrol agent. For further investigation, the strain has been combined with two other Bacillus strains (Bacillus velezensis VJH504 and Bacillus subtilis JNF2) to enhance biocontrol ability, which formed high-efficiency microbial agents in the current study. The methodological target taken is based on achieving the optimal growth conditions of the combined microbial agents; hence, the medium composition and culture conditions were optimized through a single-factor test, orthogonal test and response surface methodology. Following this, the effectiveness of the microbial combination was assessed through pot experiments, which provided a theoretical foundation for the synthesis of microbial flora to significantly control cucumber Fusarium wilt. The results showed excellent compatibility, proving suitable for the proliferation and growth of Paenibacillus polymyxa PJH16, Bacillus velezensis VJH504, and Bacillus subtilis JNF2 strains together, specifically, when the inoculation amounts were adjusted to 4% of each. Using the single-factor test and orthogonal test analysis, the optimum composition of culture medium for the composite strain was identified as 3% glucose as the optimal carbon source, 2% yeast extract powder as the preferred nitrogen source, and 1% dipotassium hydrogen phosphate as the most suitable inorganic salt. Furthermore, the optical density (OD₆₀₀) of the composite strain solution reached its highest level at 3.16 under the following culture conditions: inoculation volume of 200 µL, 171 rpm culture speed, 21.6 h culture time, 30 °C cultural temperature, and an initial pH of 7.0. The pot experiment demonstrated that the mixed bacterial solution achieved a relative control efficacy of 93.4% against cucumber Fusarium wilt, which was significantly superior to that of single- strain or pesticide treatment, and also promoted cucumber growth. In summary, the microbial flora synthesized by the three Bacillus strains displayed a high bacterial concentration, following the optimization of culture conditions, and exerted remarkable control and growth-promoting effects on cucumber Fusarium wilt. This finding holds great significance for future developments of composite microbial agents. Full article

As part of the development of alternative and environmentally friendly control against phytopathogenic fungi, Burkholderia cepacia could be a useful species notably via the generation of hydrolytic enzymes like chitinases, which can act as a biological control agent. Here, a Burkholderia contaminans S614 strain exhibiting chitinase activity was isolated from a soil in southern Tunisia. Then, response surface methodology (RSM) with a central composite design (CCD) was used to assess the impact of five factors (colloidal chitin, magnesium sulfate, dipotassium phosphate, yeast extract, and ammonium sulfate) on chitinase activity. B. contaminans strain 614 growing in the optimized medium showed up to a 3-fold higher chitinase activity. This enzyme was identified as beta-N-acetylhexosaminidase (90.1 kDa) based on its peptide sequences, which showed high similarity to those of Burkholderia lata strain 383. Furthermore, this chitinase significantly inhibited the growth of two phytopathogenic fungi: Botrytis cinerea M5 and Phoma medicaginis Ph8. Interestingly, a crude enzyme from strain S614 was effective in reducing P. medicaginis damage on detached leaves of Medicago truncatula. Overall, our data provide strong arguments for the agricultural and biotechnological potential of strain S614 in the context of developing biocontrol approaches. Full article

A bacterial strain (WM-37) was isolated from soil and identified as Streptomyces rectiviolaceus on the basis of morphological, physiological, biochemical, and 16S rRNA characteristics. The strain was screened regarding its potential use for controlling the pathogen causing peony southern blight. To enhance the secondary metabolite yield, submerged fermentation was conducted according to a single-factor trial and response surface method. Metabolite production peaked under the following conditions: 250.00 mL flask containing 100.00 mL culture medium consisting of 20.00 g·L⁻¹ soluble starch, 3.86 g·L⁻¹ ammonium sulfate, 0.50 g·L⁻¹ sodium chloride, 0.50 g·L⁻¹ dipotassium phosphate, 0.50 g·L⁻¹ magnesium sulfate, and 0.01 g·L⁻¹ ferrous sulfate; inoculation amount, 7.74%; temperature, 30 °C; initial pH, 7.00; incubation time, 7 days; and rotational speed, 160 rpm. The fermentation broth was absorbed by D101 macroporous resin and eluted with an ethanol-water gradient, after which the eluate fractions with antifungal compounds were collected, evaporated, and concentrated to obtain a crude extract. This extract was dissolved in methanol and separated by high-performance liquid chromatography. The active compound was identified as azelaic acid (C₉H₁₆O₄) on the basis of ultra-high-resolution mass spectrometry and analyses of publicly available data. These findings suggest that Streptomyces rectiviolaceus WM-37 may be a viable biocontrol agent effective against the pathogen responsible for peony southern blight. Full article

Hydroxyapatite (HAp) of different morphologies was prepared by the direct decomposition of calcium lactate pentahydrate chelates using dipotassium hydrogen phosphate under hydrothermal conditions. The proposed technique allows for precise control of the HAp crystals morphology and product purity, which are necessary for biomedical applications. The synthesis parameters such as reagent concentrations, pH, reaction time, temperature, pressure, and stirring rate were optimized in order to produce calcium phosphates (CaPs) ceramics with restricted morphologies and composition. As a result, we obtained hydroxyapatite in the form of whiskers, hexagonal rods, nano particles, flowers, and cylinders. The products were characterized according to their structure (FTIR and XRD), morphology (SEM), and functional properties, i.e., the specific surface area. The obtained results indicate that the reagent concentration and pH values have the greatest impact on the HAp properties; however, the proper combination of all the mentioned parameters should be considered when there is a need for a bioceramic with defined physicochemical properties and an appropriate morphology. Full article

One of the leading limiting factors for wider industrial production and commercialization of microbial biopesticides refers to the high costs of cultivation media. The selection of alternative sources of macronutrients crucial for the growth and metabolic activity of the producing microorganism is a necessary phase of the bioprocess development. Gaining a better understanding of the influence of the medium composition on the biotechnological production of biocontrol agents is enabled through bioprocess modelling and optimization. In the present study, after the selection of optimal carbon and nitrogen sources, two modelling approaches were applied to mathematically describe the behavior of the examined bioprocess—the production of biocontrol agents effective against aflatoxigenic Aspergillus flavus strains. The modelling was performed using four independent variables: cellulose, urea, ammonium sulfate and dipotassium phosphate, and the selected response was the inhibition-zone diameter. After the comparison of the results generated by the Response Surface Methodology (RSM) and the Artificial Neural Network (ANN) approach, the first model was chosen for the further optimization step due to the better fit of the experimental results. As the final investigation step, the optimal cultivation medium composition was defined (g/L): cellulose 5.0, ammonium sulfate 3.77, dipotassium phosphate 0.3, magnesium sulfate heptahydrate 0.3. Full article

Carbon dioxide is the most influential gas in greenhouse gasses and its amount in the atmosphere reached 412 µmol/mol in August 2020, which increased rapidly, by 48%, from preindustrial levels. A brand-new chemical industry, namely organic chemistry and catalysis science, must be developed with carbon dioxide (CO₂) as the source of carbon. Nowadays, many techniques are available for controlling and removing carbon dioxide in different chemical processes. Since the utilization of CO₂ as feedstock for a chemical commodity is of relevance today, this study will focus on how to increase CO₂ solubility in culture media used for growing microbes. In this work, the CO₂ solubility in a different medium was investigated. Sodium hydroxide (NaOH) and monoethanolamine (MEA) were added to the culture media (3.0 g/L dipotassium phosphate (K₂HPO₄), 0.2 g/L magnesium chloride (MgCl₂), 0.2 g/L calcium chloride (CaCl₂), and 1.0 g/L sodium chloride (NaCl)) for growing microbes in order to observe the difference in CO₂ solubility. Factors of temperature and pressure were also studied. The determination of CO₂ concentration in the solution was measured by gas analyzer. The result obtained from optimization revealed a maximum CO₂ concentration of 19.029 mol/L in the culture media with MEA, at a pressure of 136.728 kPa, operating at 20.483 °C. Full article

At present, De Man, Rogosa and Sharpe (MRS) broth is the medium of choice for promoting bacteriocin production. However, this medium is expensive and not applicable for large-scale production. Therefore, a low-cost and high-efficiency culture medium for bacteriocin Lac-B23 production by Lactobacillus plantarum J23 was developed. First, the effects of the composition of MRS broth on bacteriocin Lac-B23 production and bacterial growth were researched by a one variable at a time approach. Then, a Plackett-Burman design was used to screen significant components for production. Finally, the steepest ascent and central composite designs were used to obtain an optimum medium. The final composition of the modified MRS was much simpler than MRS broth, and the modified MRS contained only glucose, yeast extract, dipotassium phosphate, manganese sulfate monohydrate, Tween 80 and sodium acetate anhydrous. The highest bacteriocin Lac-B23 production reached 2560 activity units (AU)/mL in the modified MRS, which is nine times higher than that in MRS broth (280 AU/mL). Meanwhile, the cost per liter of the modified MRS (8.56 Ren Min Bi (RMB)/L) is 34.70% the cost of MRS broth (13.11 RMB/L), and the cost per arbitrary units of bacteriocin Lac-B23 in the modified MRS is approximately fourteen times more convenient (3.34 RMB/10⁶ AU) than in the MRS broth (46.82 RMB/10⁶ AU). Full article

Expired dairy products are often disposed of due to the potential health hazard they pose to living organisms. Lack of methods to recover valuable components from them are also a reason for manufactures to dispose of the expired dairy products. Milk encompasses several different components with their own functional properties that can be applied in production of food and non-food technical products. This study aims to investigate the novel approach of using liquid biphasic flotation (LBF) method for protein extraction from expired milk products and obtaining the optimal operating conditions for protein extraction. The optimized conditions were found at 80% concentration ethanol as top phase, 150 g/L dipotassium hydrogen phosphate along with 10% (w/v) milk as bottom phase, and a flotation time of 7.5 min. The protein recovery yield and separation efficiency after optimization were 94.97% and 86.289%, respectively. The experiment has been scaled up by 40 times to ensure it can be commercialized, and the protein recovery yield and separation efficiency were found to be 78.92% and 85.62%, respectively. This novel approach gives a chance for expired milk products to be changed from waste to raw materials which is beneficial for the environment and the economy. Full article

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg₂Al-CO₃ or Mg₂Fe-CO₃ layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K₂HPO₄). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K₂HPO₄ (9 h milling, 2:1 molar ratio, MR). Compared to readily used K₂HPO₄, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K₂HPO₄ and MgFe/K₂HPO₄ composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K₂HPO₄ composites leads to a noticeable improvement of P release properties. Full article

The electrochemical behaviors of thiazolidine (tetrahydrothiazole) on gold and platinum electrodes were investigated in a Britton-Robinson buffer (pH 2.77–11.61), acetate buffer (pH 4.31), phosphate buffer solutions (pH 2.11 and 6.38) and methanol or acetonitrile containing various supporting electrolytes. Detection was based on a gold wire electrochemical signal obtained with a supporting electrolyte containing 20% methanol-1.0 mM of phosphate buffer (pH 6.87, potassium dihydrogen phosphate and dipotassium hydrogen phosphate) as the mobile phase. Comparison with results obtained with a commercial amperometric detector shows good agreement. Using the chronoamperometric sensor with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.05 to 16 mg L⁻¹ was found. The limit of quantification (LOQ) of the method for thiazolidine was found to be 1 ng. Full article