pH Changes Research Articles

Encapsulation of Peperomia pellucida (L.) kunth leaf extract for postharvest preservation of Malang apple (Malus sylvestris) at ambient storage

This study investigated the efficacy of edible coatings based on encapsulated Peperomia pellucida leaf extract to extend the shelf life of Malang apples. An edible coating was developed by encapsulating P. pellucida leaf extract using a chitosan-STPP matrix. The optimum encapsulation efficiency observed of polyphenols and flavonoids retention was 86.25% ± 0.02 and 83.30% ± 0.04, respectively. It achieved by 2.5% chitosan, 2% STPP, and 3.5% extract in formula. The encapsulated extract was further applied to Malang apples as edible coated using varying dipping times and stored for 15 days at ambient temperature. Evaluation parameters on coated Malang apples included hardness, weight loss, pH, moisture content, and color change. A 1-min dipping time of the encapsulated extract was found to be optimal, effectively reducing physical and chemical alterations and enhancing the shelf-life quality of the apples. Therefore, the edible coating derived from encapsulated P. pellucida leaf extract presents a promising alternative for preserving Malang apples.

The impact of land-use changes and management intensification on bacterial communities in the last decade: a review.

In the last decade, advances in soil bacterial ecology have contributed to increasing agricultural production. Brazil is the world leading agriculture producer and leading soil biodiversity reservoir. Meanwhile, there is still a significant gap in the knowledge regarding the soil microscopic life and its interactions with agricultural practices, and the replacement of natural vegetation by agroecosystems is yet to be unfolded. Through high throughput DNA sequencing, scientists are now exploring the complexity of soil bacterial communities and their relationship with soil and environmental characteristics. This study aimed to investigate the progress of bacterial ecology studies in Brazil over the last 10 years, seeking to understand the effect of the conversion of natural vegetation in agricultural systems on the diversity and structure of the soil microbial communities. We conducted a systematic search for scientific publication databases. Our systematic search has matched 62 scientific articles from three different databases. Most of the studies were placed in southeastern and northern Brazil, with no records of studies about microbial ecology in 17 out of 27 Brazilian states. Out of the 26 studies that examined the effects of replacing natural vegetation with agroecosystems, most authors concluded that changes in soil pH and vegetation cover replacement were the primary drivers of shifts in microbial communities. Understanding the ecology of the bacteria inhabiting Brazilian soils in agroecosystems is paramount for developing more efficient soil management strategies and cleaner agricultural technologies.

Pathogenesis‐Guided Engineering: pH‐Responsive Imprinted Polymer Co‐Delivering Folate for Inflammation‐Resolving as Immunotherapy in Implant‐Related Infections

AbstractFolate (FT) is a suitable targeting ligand for folate receptors (FOLR) overexpressed on inflamed cells. Thus, FT‐loaded polymers can be used as FOLRs‐targeted immunotherapy to positively modulate the inflammatory process. A novel biodegradable imprinted polymer with a FT delivery mechanism driven by pH changes [PCL‐MIP@FT] is designed with molecularly imprinted technology. The pH mechanism is validated in vitro, demonstrating that an acidic environment accelerated and increased the release of FT for a period of 7 days (∼100 µg mL−1). For the first time, FT receptors (FOLR‐1 and FOLR‐3) are discovered and also overexpressed on activated human gingival fibroblasts, representing a favorable target in the oral environment. Although FT itself does not have antimicrobial effects, the nanomechanical properties of biofilm are changed after topical FT administration. In vivo systemic toxicity of PCL‐MIP@FT has been demonstrated to be a safe biomaterial (up to 1.3 mg kg−1). When the PCL‐MIP@FT is assessed in the subcutaneous tissue, it promoted an alleviating inflammation and may be able to stimulate tissue repair. The present findings have demonstrated the reliable in vitro and in vivo anti‐inflammatory actions of FT‐loaded polymer and support its use as a novel drug‐free therapeutic platform for modulating and mitigating inflammatory responses in dental implant‐related infections.

Proton-Induced Reversible Spin-State Switching in Octanuclear FeIII Spin-Crossover Metal-Organic Cages.

Responsive spin-crossover (SCO) metal-organic cages (MOCs) are emerging dynamic platforms with potential for advanced applications in magnetic sensing and molecular switching. Among these, FeIII-based MOCs are particularly noteworthy for their air stability, yet they remain largely unexplored. Herein, we report the synthesis of two novel FeIII MOCs using a bis-bidentate ligand approach, which exhibit SCO activity above room temperature. These represent the first SCO-active FeIII cages and feature an atypical {FeN6}-type coordination sphere, uncommon for FeIII SCO compounds. Our study reveals that these MOCs are sensitive to acid/base variations, enabling reversible magnetic switching in solution. The presence of multiple active proton sites within these SCO-MOCs facilitates multisite, multilevel proton-induced spin-state modulation. This behavior is observed at room temperature through 1H NMR spectroscopy, capturing the subtle proton-induced spin-state transitions triggered by pH changes. Further insights from extended X-ray absorption fine structure (EXAFS) and theoretical analyses indicate that these magnetic alterations primarily result from the protonation and deprotonation processes at the NH active sites on the ligands. These processes induce changes in the secondary coordination sphere, thereby modulating the magnetic properties of the cages. The capability of these FeIII MOCs to integrate magnetic responses with environmental stimuli underscores their potential as finely tunable magnetic sensors and highlights their versatility as molecular switches. This work paves the way for the development of SCO-active materials with tailored properties for applications in sensing and molecular switching.

Coaxial-Tube Quantitative Nuclear Magnetic Resonance for Various Solutions Using SI-Traceable Concentration References.

Quantitative nuclear magnetic resonance (qNMR) is an accepted method for determining analyte concentrations using quantitative substances in one spectrum. Conventional qNMR is performed using a mixture of analytes and reference substances. In coaxial-tube NMR, two tubes are used as different solutions, similar to normal NMR spectra. Currently, coaxial tubes with various diameters are available; however, coaxial-tube qNMR is limited, and a general analytical protocol is yet to be proposed. In this study, we established an effective volume ratio (EVR) measurement method using the weight density and qNMR methods. Various analyte concentrations were determined using coaxial-tube qNMR and an SI-traceable reagent. The EVR required for the qNMR concentration calculation was determined using a coefficient of variation (CV) of <1% for an inner tube of ϕ 3 mm or less. The peak integral of each substance was correlated with the effective volume, depending on the abundance of the tube and matched 1H in the solution. The T1 relaxation times differed depending on the substructure, and the T1 values of the formate and OH groups varied for each tube set. Thus, each partial structural characteristic of the peak must be understood before qNMR is performed. The concentrations of various substances, including hygroscopic substances, were determined using coaxial-tube qNMR. Coaxial tubes eliminate the need to mix the analyte with the reference substance; thus, we can quantify the analyte without causing pH and structural changes caused by other mixtures and reuse the analyte for other test systems.

The Arrestin-like Protein palF Contributes to Growth, Sporulation, Spore Germination, Osmolarity, and Pathogenicity of Coniella vitis.

Coniella vitis is a dominant phytopathogen of grape white rot in China, significantly impacting grape yield and quality. Previous studies showed that the growth and pathogenicity of C. vitis were affected by the environmental pH. Arrestin-like protein PalF plays a key role in mediating the activation of an intracellular-signaling cascade in response to alkaline ambient. However, it remains unclear whether palF affects the growth, development, and virulence of C. vitis during the sensing of environmental pH changes. In this study, we identified a homologous gene of PalF/Rim8 in C. vitis and constructed CvpalF-silenced strains via RNA interference. CvpalF-silenced strains exhibited impaired fungal growth at neutral/alkaline pH, accompanied by reduced pathogenicity compared to the wild-type (WT) and empty vector control (CK) strains. The distance between the hyphal branches was significantly increased in the CvpalF-silenced strains. Additionally, CvpalF-silenced strains showed increased sensitivity to NaCl, H2O2, and Congo red, and decreased sensitive to CaSO4. RT-qPCR analysis demonstrated that the expression level of genes related to pectinase and cellulase were significantly down-regulated in CvpalF-silenced strains compared to WT and CK strains. Moreover, the expression of PacC, PalA/B/C/F/H/I was directly or indirectly affected by silencing CvpalF. Additionally, the expression of genes related to plant cell wall-degrading enzymes, which are key virulence factors for plant pathogenic fungi, was regulated by CvpalF. Our results indicate the important roles of CvpalF in growth, osmotolerance, and pathogenicity in C. vitis.

Impact of Lactic Acid Fermentation on the Organic Acids and Sugars of Developed Oat and Buckwheat Beverages

In recent years, new plant-based foods and drinks have been developed to meet the growing demand for animal-derived alternatives, particularly dairy products. This study investigates the impact of lactic acid fermentation on the organic acids and sugars in oat and buckwheat beverages developed using Lactobacillus johnsonii K4 and Lacticaseibacillus rhamnosus K3, which are potential probiotics. The fermented samples were analyzed for pH changes, bacterial viability, and the concentration of organic acids and sugars over 15 days. The results indicated significant variations in bacterial colony counts, with L. johnsonii K4 showing the highest initial growth. Over 15 days, pH levels decreased, with the most acidic conditions observed in buckwheat beverages. Notably, fermentation led to a significant increase in acetic acid concentration and a reduction in malic acid levels, particularly in buckwheat samples. These findings highlight the dynamic nature of fermentation in enhancing the nutritional profile and shelf-life of plant-based beverages.

Real-time tracking of fish quality using a cellulose filter paper colorimetric indicator incorporated with prickly pear fruit betacyanins

In the present work, a freshness indicator was developed by immobilizing extracted betacyanins from prickly pear fruit (PFB) onto cellulose filter paper to visually determine fish spoilage. Various properties of the prepared indicator, including color stability, moisture uptake, sensivity to hydrogen sulfide (H2S) gas and pH changes, and chemical analysis were studied. The PFB-based indicator exhibited good color stability at various temperatures and times, with no significan color changes observed during storage at 25, 4, and −18 °C for 8 days. The moisture absorption of the indicator based on PFB was lower than that of cellulose paper, which is crucial for colorimetric indicators. Basic nitrogen and sulfur compounds are the main volatile compounds produced during fish spoilage. The results of the present study showed that both total volatile basic nitrogen (TVB-N) and H2S gas produced during fish spoilage contributed to the color changes of betacyanin-based colorimetric indicators. The prepared freshness indicators were pH-sensitive, with significant color changes due to TVB-N and H2S production during fish storage. A significant correlation was observed between fish quality (pH, TVB-N and total viable count) and the visible color changes of the indicators. The color of the designed indicator shifted from dark pink to pale pink/white during fish storage. These prepared freshness indicators were inexpensive, easy to use, and non-toxic, making them suitable for assessing the quality and shelf life of fish fillets.

Baicalin suppresses type 2 dengue virus-induced autophagy of human umbilical vein endothelial cells by inhibiting the PI3K/AKT pathway

To investigate the effect of type 2 dengue virus (DENV-2) infection on autophagy in human umbilical vein endothelial cells (HUVECs) and the mechanism mediating the inhibitory effect of baicalin against DENV-2 infection. Cultured HUVECs with DENV-2 infection were treated with different concentrations of baicalin, and the changes in autophagy of the cells were detected using transmission electron microscopy. Lyso Tracker Red staining was used to examine pH changes in the lysosomes of the cells, and the expressions of ATG5, beclin-1, LC3, P62, STX17, SNAP29, VAMP8, and PI3K/AKT signaling pathway-related proteins were detected by Western blotting. DENV-2 replication in the cells were evaluated using RT-qPCR. The differentially expressed proteins in DENV-2-infected HUVECs were identified by proteomics screening. Treatment with baicalin did not significantly affect the viability of cultured HUVECs. Proteomic studies suggested that the PI3K-AKT pathway played an important role in mediating cell injury induced by DENV-2 infection. The results of RT-qPCR demonstrated that baicalin dose-dependently inhibited DENV-2 replication in HUVECs and produced the strongest inhibitory effect at the concentration of 50 μg/mL. Transmission electron microscopy, Lyso Tracker Red staining, RT-qPCR, and Western blotting all showed significant inhibitory effect of baicalin on DENV-2-induced autophagy in HUVECs. DENV-2 infection of HUVECs caused increased cellular expressions of LC3 and P62 proteins, which were significantly lowered by treatment with LY294002 (a PI3K inhibitor). Baicalin inhibits DENV-2 replication in HUVECs and suppresses DENV-2-induced cell autophagy by inhibiting the PI3K/AKT signaling pathway.

Mesoporous Fe3O4/SiO2/poly(2-carboxyethyl acrylate) composite polymer particles for pH-responsive loading and targeted release of bioactive molecules.

pH-responsive polymer microspheres undergoing reversible changes in their surface properties have been proved useful for drug delivery to targeted sites. This paper is aimed at preparing pH-responsive polymer-modified magnetic mesoporous SiO2 particles. First, mesoporous magnetic (Fe3O4) core-particles are prepared using a one-pot solvothermal method. Then, magnetic Fe3O4 particles are covered with a C[double bond, length as m-dash]C functional mesoporous SiO2 layer before seeded emulsion polymerization of 2-carboxyethyl acrylate (2-CEA). The composite polymer particles are named Fe3O4/SiO2/P(2-CEA). The average diameters of the Fe3O4 core and Fe3O4/SiO2/P(2-CEA) composite polymer particles are 414 and 595 nm, respectively. The mesoporous (pore diameter = 3.41 nm) structure of Fe3O4/SiO2/P(2-CEA) composite polymer particles is confirmed from Brunauer-Emmett-Teller (BET) surface analysis. The synthesized Fe3O4/SiO2/P(2-CEA) composite polymer exhibited pH-dependent changes in volume and surface charge density due to deprotonation of the carboxyl group under alkaline pH conditions. The change in the surface properties of Fe3O4/SiO2/P(2-CEA) composite polymer particles following pH change is confirmed from the pH-dependent sorption of cationic methylene blue (MB) and anionic methyl orange (MO) dye molecules. The opening of the pH-responsive P(2-CEA) gate valve at pH 10.0 allowed the release of loaded vancomycin up to 99% after 165 min and p-acetamido phenol (p-AP) up to 46% after 225 min. Comparatively, the amount of release is lower at pH 8.0 but still suitable for drug delivery applications. These results suggested that the mesoporous Fe3O4/SiO2 composite seed acted as a microcapsule, while P(2-CEA) functioned as a gate valve across the porous channel. The prepared composite polymer can therefore be useful for treating intestine/colon cancer, where the pH is comparatively alkaline.

PH-responsive collagen nanocomposite films reinforced by curcumin-loaded Laponite nanoplatelets for dynamic visualization of shrimp freshness

Sustainable and intelligent packaging systems, utilizing biomass-derived matrix and bioactive indicators represent promising approaches for real-time detection and monitoring of freshness of food, as well as prolonging the shelf-life and improving the quality and safety of food products. Herein, we reported pH-responsive collagen nanocomposite films reinforced by curcumin-loaded Laponite nanoplatelets which could act as smart indicators for monitoring the freshness of shrimps. Caffeic acid, as a bio-based modifier, was covalently grafted onto the surfaces of the nanoplatelets loaded with curcumin. The collagen nanocomposite films were fabricated by the incorporation of functionalized nanoplatelets through all-aqueous casting-evaporation approach. The triple-helical structure of collagen molecules was stabilized by the functionalized nanoplatelets mainly through hydrogen bonding and electrostatic interactions with uniform distribution into the film matrix. Moreover, the resultant nanocomposite films not only demonstrated favorable hydrophobicity and water vapor barrier properties, but also exhibited effective antioxidant activity and anticipated color responsiveness to pH changes and NH3 presence. The consistent changes in color of the nanocomposite film with the shrimps following days of storage supported its feasibility and potential for monitoring the freshness of shrimps. Therefore, we envision that the developed collagen-based nanocomposite films showcase great potential in the application of sustainable and intelligent packaging system for dynamic visualization of seafood freshness.

Investigation of the influence of pH and temperature on melanization and survival under oxidative stress in Cryptococcus neoformans.

Cryptococcus neoformans is an opportunistic pathogenic fungus that produces melanin during infection, an important virulence factor in Cryptococcal infections that enhances the ability of the fungus to resist immune defense. This fungus can synthesize melanin from a variety of substrates, including L-DOPA (L-3,4-dihydroxyphenylalanine). Since melanin protects the fungus from various stress factors such as oxidative, nitrosative, extreme heat and cold stress; we investigated the effects of environmental conditions on melanin production and survival. In this study, we investigated the effects of different pH values (5.6, 7.0 and 8.5) and temperatures (30°C and 37°C) on melanization and cell survival using a microtiter plate-based melanin production assay and an oxidative stress assay, respectively. In addition, the efficacy of compounds known to inhibit laccase involved in melanin synthesis, i.e., tunicamycin, β-mercaptoethanol, dithiothreitol, sodium azide and caspofungin on melanization was evaluated and their sensitivity to temperature and pH changes was measured. The results showed that melanin content correlated with pH and temperature changes and that pH 8.5 and 30°C, were best for melanin production. Besides that, melanin production protects the fungal cells from oxidative stress induced by hydrogen peroxide. Thus, changes in pH and temperature drastically alter melanin production in C. neoformans and it correlates with the fungal survival. Due to the limited antifungal repertoire and the development of resistance in cryptococcal infections, the investigation of environmental conditions in the regulation of melanization and survival of C. neoformans could be useful for future research and clinical phasing.

Effects of Nitrate and Nitrite on Plaque pH Decrease and Nitrite-Producing and -Degrading Activities of Plaque in vitro.

The purpose of this study was to investigate the effects of nitrate and nitrite on the pH-lowering activity of human plaque, the nitrite-producing and -degrading activities of human plaque, and their correlation. Nitrate and nitrite were added to human plaque suspensions collected from the buccal aspect of maxillary molars of patients visiting a general dental clinic, and changes in pH were measured with and without glucose addition. Nitrite-producing and -degrading activities were evaluated by adding nitrate and nitrite to the plaque suspension and measuring the increase and decrease in nitrite with Griess reagent, respectively. The addition of nitrate inhibited both endogenous and glucose-induced plaque pH-lowering. The addition of glucose enhanced the production of nitrite from nitrate by about 3.3-fold. The addition of nitrite also inhibited endogenous plaque pH-lowering, but the addition of glucose promoted nitrite degradation by only about 1.1-fold. Nitrite-producing activity was positively correlated with age, but not with nitrite-degrading activity. This study revealed that nitrite was produced from nitrate and inhibited the pH-lowering activity of human plaque, which may contribute to caries control. Both nitrite-producing and -degrading activities occurred in human plaque, but no correlation was found between them. Furthermore, nitrite production was enhanced by glucose metabolism, which may function as a self-regulatory mechanism (resilience) to prevent excessive acidification by glucose metabolism.

Chemical changes in thermally modified, acetylated and melamine formaldehyde resin impregnated beech wood

Abstract Wood modification (by thermal or chemical treatment) helps to improve the dimensional stability of wood and enhance its resistance to biological agents. Beech wood is non-durable and exposure in exterior settings dramatically shortens its service life. To determine the full potential of beech wood for advanced applications, a better understanding of the chemical changes induced by modification is needed. Two chemical treatments (acetylation and melamine formaldehyde resin impregnation) and three thermal treatments (heating to 180, 200 and 220 °C) were performed on beech wood. The modification effect was examined based on (i) molecular changes in functional groups by Fourier-transform infrared spectroscopy (ATR-FTIR); (ii) extractive content; and (iii) pH changes. Moreover, the explanation of these changes was supported by the FTIR-analysis of isolated main wood components (cellulose, holocellulose and lignin) from the modified wood. The high temperatures applied to samples during thermal modification promoted the deacetylation and degradation of hemicelluloses. Hemicelluloses were targeted also by acetic anhydride and melamine resin, the bonding of which was confirmed by FTIR analysis. The formation of fewer methylene bridges affected the properties of the melamine network. This observation suggests the need to determine optimal curing conditions in future research, to reduce melamine-wood hydrophilicity.

The Effect of Infusing Soursop Leaves (Annona muricata L.) on Vaginal Discharge in Women of Childbearing Age: A Randomized Clinical Trial at the Lolo Community Health Center, Kerinci Regency, Jambi, Indonesia

Introduction: Vaginal discharge (leukorrhea) is a common gynecological complaint among women of childbearing age. While physiological discharge is normal, pathological discharge can be indicative of underlying infections or conditions. This study aimed to investigate the efficacy of soursop leaf infusion (Annona muricata L.) as a complementary treatment for vaginal discharge in women of childbearing age. Methods: A randomized controlled trial was conducted at the Lolo Community Health Center, Kerinci Regency, Jambi, Indonesia. Women aged 15-49 years presenting with vaginal discharge were randomly assigned to either the intervention group (soursop leaf infusion) or the control group (standard care). The intervention group received soursop leaf infusion twice daily for seven days, while the control group received standard care as per the health center's protocol. The primary outcome was the reduction in vaginal discharge symptoms (amount, color, odor, and associated discomfort) after seven days. Secondary outcomes included changes in vaginal pH and microbiological assessment. Results: A total of 130 women participated in the study (65 in each group). After seven days, the intervention group showed a significantly greater reduction in vaginal discharge symptoms compared to the control group (p &lt; 0.05). The amount, color, and odor of discharge improved significantly in the intervention group, along with a reduction in associated discomfort such as itching and irritation. Vaginal pH was also normalized in the intervention group, and microbiological assessment revealed a decrease in pathogenic microorganisms. Conclusion: Soursop leaf infusion (Annona muricata L) appears to be a safe and effective complementary treatment for vaginal discharge in women of childbearing age. Its antimicrobial and anti-inflammatory properties may contribute to its beneficial effects. Further research is warranted to explore its long-term efficacy and potential use in combination with conventional therapies.

Research on the mechanism of copper removal during electromagnetic enhanced aerobic fermentation of sludge

The migration and transformation of copper during magneto electric assisted aerobic fermentation were studied by establishing a control group, a magnetic assisted group (1.4 mT), an electric assisted group (10 V), and a magneto electric assisted group. The results showed that during the aerobic fermentation process of magnetic assisted sludge, changes in pH, temperature, and microorganisms in the system promoted the dissolution of Cu2+ and its migration from solid sludge to fermentation broth. Due to the presence of an electric field, Cu2+ deposits on the cathode plate through anisotropic attraction, combined with the Lorentz force generated by the magnetic field, promoting mass transfer of copper ions and reducing the concentration of Cu2+ in the fermentation broth, resulting in a copper removal rate of up to 75 %. In addition, the COMSOL simulation results show a consistent overall trend with actual experiments, indicating that the external electric and magnetic fields have a significant inhibitory effect on the removal of heavy metals in sludge.

Experimental Correlation between Apparent pKa and Gelation Propensity in Amphiphilic Hydrogelators Derived from l-Dopa.

We report the gelation propensity of three gelators derived from l-dihydroxyphenylalanine (l-Dopa), where the amino group is derivatized with three different fatty acids (lauric acid, palmitic acid, and azelaic acid). The long aliphatic side chains should introduce additional van der Waals interactions among the molecules, contributing to the self-assembly process. The hydrogels have been prepared with the pH change method, and both the hydrogels and the corresponding aerogels have been analyzed using several techniques. In any case, Lau-Dopa provides stronger hydrogels compared with the other gelators. This property may be ascribed to its tendency to efficiently form supramolecular β-sheet structures, as outlined by the ECD, IR, and SEM analyses. Moreover, the preliminary measurement of the apparent pKa displays for Lau-Dopa two plateaux, as previously observed for, one at about pH 12 and a second one at pH 7.5. Thus, its pKa results in two apparent pKa shifts of ∼8.5 and ∼4 pH units above the theoretical pKa, as a consequence of a multistep self-assembly pathway that correlates, in the final β-sheet-based hydrogel, with a high degree of order and stability.

Ready, Set, Grow: From Micelles to Giant Vesicles via Biocatalytic Activation.

Controlling physicochemical processes that drive changes in supramolecular aggregates is an important objective toward creating artificial soft micro- and nanomachines. Previous research explored the morphology control of membrane-based materials subjected to externally imposed chemical stimuli. Here, we modulate the microscale morphology of pH-responsive assemblies by using biocatalysis to internally generate changes in global pH. Catalytic reactions offer flexibility in the mechanism and rate at which stimuli are introduced to responsive assemblies, ultimately enabling precision and control over size and morphology. We observed, by dynamic light scattering and fluorescence microscopy, substantial microscale differences between assemblies subjected to manually titrated pH changes compared to biocatalytically activated pH changes, including the growth of giant vesicles from micelles. Coarse-grained molecular dynamics simulations of these metastable self-assembled structures provided insight into the thermodynamics and kinetics of the preferred structures. These results demonstrate the feasibility of using biocatalytic reactions to modulate the size and morphology of supramolecular assemblies, from micelles to giant vesicles.

The influence of an alternating magnetic field with a different signal shape on the morphometry and ontogenesis of &lt;i&gt;Zea mays&lt;/i&gt; L.

The paper considers the issues of factorial ecology concerning the mechanisms of influence of physical factors, in particular, an alternating magnetic field with different characteristics, on plant objects. The obtained biological effects on Zea mays L. seeds depend to a greater extent on the shape of the applied signal. It is assumed that physiological responses are associated with a change in pH, the release of proteins, and also with the barrier function of plant seed membranes. The obtained schemes for processing sugar corn with an alternating magnetic field, taking into account ontogenesis and morphometry, are further recommended to be used in the field as a method of presowing treatment of agricultural crops: B = 1 mT, f = 20 Hz, t = 60 min, sinusoid signal type; B = 1 mT, f = 50 Hz, t = 60 min, sinusoid signal type; B = 1 mT, f = 30 Hz, t = 60 min, meander signal type; B = 1 mT, f = 50 Hz, t = 60 min, meander signal type; B = 1 mT, f = 20 Hz, t = 60 min, meander signal type.

Biochemical characterisation and production kinetics of high molecular-weight (HMW) putative antibacterial proteins of insect pathogenic Brevibacillus laterosporus isolates

BackgroundBacterial genomes often encode structures similar to phage capsids (encapsulins) and phage tails which can be induced spontaneously or using genotoxic compounds such as mitomycin C. These high molecular-weight (HMW) putative antibacterial proteins (ABPs) are used against the competitive strains under natural environment. Previously, it was unknown whether these HMW putative ABPs originating from the insect pathogenic Gram-positive, spore-forming bacterium Brevibacillus laterosporus (Bl) isolates (1821L, 1951) are spontaneously induced during the growth and pose a detrimental effect on their own survival. Furthermore, no prior work has been undertaken to determine their biochemical characteristics.ResultsUsing a soft agar overlay method with polyethylene glycol precipitation, a narrow spectrum of bioactivity was found from the precipitated lysate of Bl 1951. Electron micrographs of mitomycin C- induced filtrates showed structures similar to phage capsids and contractile tails. Bioactivity assays of cell free supernatants (CFS) extracted during the growth of Bl 1821L and Bl 1951 suggested spontaneous induction of these HMW putative ABPs with an autocidal activity. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of spontaneously induced putative ABPs showed appearance of ~ 30 kDa and ~ 48 kDa bands of varying intensity across all the time intervals during the bacterial growth except in the initial hours. Statistically, spontaneously induced HMW putative ABPs of Bl 1951 exhibited a significant decrease in the number of viable cells of its producer strain after 18 h of growth in liquid. In addition, a significant change in pH and prominent bioactivity of the CFS of this particular time period was noted. Biochemically, the filtered supernatant derived from either Bl 1821L or Bl 1951 maintained bioactivity over a wide range of pH and temperature.ConclusionThis study reports the spontaneous induction of HMW putative ABPs (bacteriocins) of Bl 1821L and Bl 1951 isolates during the course of growth with potential autocidal activity which is critically important during production as a potential biopesticide. A narrow spectrum of putative antibacterial activity of Bl 1951 precipitate was found. The stability of HMW putative ABPs of Bl 1821L and Bl 1951 over a wide range of pH and temperature can be useful in expanding the potential of this useful bacterium beyond the insecticidal value.