Elevated pH Levels Research Articles

Efficient arsenic removal from water using iron-impregnated low-temperature biochar derived from henequen fibers: performance, mechanism, and LCA analysis

The present study aims to investigate the low-energy consumption and high-efficiency removal of arsenic from aqueous solutions. The designed adsorbent Fe/TBC was synthesized by impregnating iron on torrefaction henequen fibers. Isothermal adsorption experiments indicated maximum adsorption capacities of 7.30 mg/g and 8.98 mg/g for arsenic(V) at 25.0 °C and 40.0 °C, respectively. The interference testing showed that elevated levels of pH, HCO3− concentration, and humic acid content in the solution could inhibit the adsorption of arsenic by Fe/TBC. Characterization of the adsorbent before and after adsorption using FTIR and SEM–EDS techniques confirmed arsenic adsorption mechanisms, including pore filling, electrostatic interaction, surface complexation, and H-bond adhesion. Column experiments were conducted to treat arsenic-spiked water and natural groundwater, with effective treatment volumes of 550 mL and 8792 mL, respectively. Lastly, the life cycle assessment (LCA) using OpenLCA 2.0.3 software was performed to treat 1 m3 of natural groundwater as the functional unit. The results indicated relatively significant environmental impacts during the Fe/TBC synthesis stage. The global warming potential resulting from the entire life cycle process was determined to be 0.8 kg CO2-eq. The results from batch and column experiments, regeneration studies, and LCA analysis indicate that Fe/TBC could be a promising adsorbent for arsenic(V).

Utilizing Mixed Cultures of Microalgae to Up-Cycle and Remove Nutrients from Dairy Wastewater.

This study explores the novel use of mixed cultures of microalgae-Spirulina platensis, Micractinium, and Chlorella-for nutrient removal from dairy wastewater (DW). Microalgae were isolated from a local wastewater treatment plant and cultivated under various light conditions. The results showed significant biomass production, with mixed cultures achieving the highest biomass (2.51 g/L), followed by Spirulina (1.98 g/L) and Chlorella (1.92 g/L). Supplementing DW (75%) with BG medium (25%) significantly enhanced biomass and pH levels, improving pathogenic bacteria removal. Spirulina and mixed cultures exhibited high nitrogen removal efficiencies of 92.56% and 93.34%, respectively, while Chlorella achieved 86.85% nitrogen and 83.45% phosphorus removal. Although growth rates were lower under phosphorus-limited conditions, the microalgae adapted well to real DW, which is essential for effective algal harvesting. Phosphorus removal efficiencies ranged from 69.56% to 86.67%, with mixed cultures achieving the highest removal. Microbial and coliform removal efficiencies reached 97.81%, with elevated pH levels contributing to significant reductions in fecal E. coli and coliform levels. These findings suggest that integrating microalgae cultivation into DW treatment systems can significantly enhance nutrient and pathogen removal, providing a sustainable solution for wastewater management.

Impact of varying dissolved organic carbon load on sediment phosphorus release and its periodic mechanisms

Phosphorus (P) release from sediment poses a severe challenge for eutrophication management in the aquatic environment. The dissolved organic carbon (DOC) concentrations in riverine ecosystems have shown an increasing trend due to intensified climate change and anthropogenic activities, while their impact on sediment P cycling remains unclear. To investigate the effects of different DOC loads on sediment P release and the underlying mechanisms, we conducted a two-month experiment in 15 plexiglass tanks, with five gradient-increasing target DOC concentrations set according to reality: control (S0), 5 mg/L (S5), 10 mg/L (S10), 15 mg/L (S15), and 20 mg/L (S20). The results demonstrated that: i) DOC enrichment promoted the sediment P mobilization and release, with the underlying mechanisms exhibited periodic characteristics. ii) reduced dissolved oxygen (DO) concentration and stimulated alkaline phosphatase activity (APA) were likely the primary and sustained facilitating mechanisms. While after the termination of DOC load, elevated pH level was also considered a contributing factor when chlorophyll a (Chl a) ranged between 5.9 μg/L and 7.7 μg/L iii) ultimate concentration of total P (TP) in the overlying water depended on DOC load. After DOC addition was terminated, decreased TP concentrations were observed when DOC concentration was in the range of 5–15 mg/L, which may be attributed to the direct uptake of P by phytoplankton counteracting the minor promotion of P release induced by anoxic conditions. However, when DOC concentrations exceeded 15–20 mg/L, there were notable increments in TP concentrations. Our findings provide further insight into the response mechanisms of sediment P release to the increasing organic C load in natural ecosystems. The impact of broader C forms or C loads on sediment P cycling needs to be fully elucidated and even quantified in future studies, especially through large-scale field investigations to further clarify the coupled roles between C and P.

Novel theranostic wounds dressing based on pH responsive alginate hydrogel/graphene oxide/levofloxacin modified silk

Integrating pH sensor with controlled antibiotic release is fabricated on silk to create a theranostic wound dressing. Alginate (ALG) hydrogel and graphene oxide (GO) loaded with levofloxacin (LVX) and a pH indicator are applied to fabricate a pH-responsive theranostic wound dressing. The modified silk color changes from yellow to green in response to elevated skin pH, indicating the skin infection. The semi-quantitative analysis was conducted using ImageJ, revealing significant color changes across the wide range. At elevated pH levels, the ionization of the COOH bonds within ALG induces repulsion among the COO− groups, thereby accelerating the release of the incorporated drug compared to release under lower pH. At an infected pH of 8, ALG hydrogel triggers LVX releasing up to 135.86 ± 0.3 µg, while at a normal pH of 7, theranostic silk releases 123.13 ± 0.26 µg. Incorporating GO onto silk fibers enhances LVX loading and sustains LVX release. Furthermore, these modified silks possess antimicrobial abilities without causing irritation or allergies on the human skin. This theranostic silks represents a major step forward in smart wound care, introducing a versatile platform of smart wound care.

Exploring the Current Status of Groundwater Resources in Herat City, Afghanistan: An In-depth Analysis

Groundwater depletion and pollution pose significant challenges to water security in Herat City, Afghanistan. Utilizing data collected from monitoring and research wells up to March 2023, this study assesses the static water levels and quality parameters across various regions. The analysis reveals a consistent decline in groundwater levels from 2015 to 2022, with reductions exceeding 10% in some areas. Additionally, water quality assessments based on WHO standards highlight elevated levels of electrical conductivity, salinity, and pH, indicating contamination and unsuitability for consumption and irrigation. Salinity levels in certain wells exceed recommended limits, reaching up to 1400 mg/L. Moreover, increased pH levels suggest pollutant infiltration from agricultural and wastewater sources. To address these challenges, sustainable management strategies are proposed, including centralized and decentralized wastewater treatment, standardized irrigation practices, and the promotion of responsible water usage. Collaboration among stakeholders and robust governance frameworks are essential for implementing these measures and ensuring long-term groundwater sustainability in Herat City. Continuous monitoring of water quantity alongside quality is emphasized to track progress and adjust strategies accordingly, safeguarding the availability and quality of groundwater resources. The outcome underscores the urgent need for comprehensive interventions to safeguard public health and secure access to safe drinking water in Herat City, Afghanistan.

Disorders of the small intestinal microenvironment in ovalbumin-sensitized mice and mitigation strategies of 2′-fucosyllactose and Bifidobacterium longum subsp. Infantis

The small intestine is responsible for approximately 90% of nutrient absorption, and it is widely believed that food allergens primarily sensitize through the small intestine. No study to date has investigated the association between food allergy (FA) and the altered small intestinal microenvironment (SIM), which would help to understand the biological process linking FA, and could provide new insights into the nutritional modulation of FA. In this study, we aimed to investigate the association between the development of FA and the altered SIM in ovalbumin-sensitized mice, as well as elucidate the underlying mechanisms by which Bifidobacterium longum subsp. Infantis (B. infantis) and/or 2′-fucosyllactose regulate allergenic reactions from the perspective of SIM. Our findings demonstrate that ovalbumin-induced disruption of SIM is characterized by increased bacteria diversity, dysregulated production of organic acids and amino acids, elevated ileal pH levels, and disrupted intestinal tight junctions. Furthermore, B. infantis and 2′-fucosyllactose cotreatment most significantly repaired ovalbumin sensitization-induced SIM dysbiosis compared to mono-treatment with either B. infantis or 2′-fucosyllactose alone. Additionally, impaired intestinal barrier function may impact lung homeostasis by influencing material exchange between the lumen and tissues, thereby increasing susceptibility to pulmonary. Notably, B. infantis and/or 2′-fucosyllactose differentially regulated both SIM and lung homeostasis. The present study supports the notion that disrupted small intestinal microenvironment homeostasis underlie the development of food allergy and highlights the significance of the small intestine-lung axis as a target for probiotic and/or prebiotic-mediated modulation of food allergy.

Revolutionizing Wound Healing: Exploring Scarless Solutions through Drug Delivery Innovations.

Human skin is the largest organ and outermost surface of the human body, and due to the continuous exposure to various challenges, it is prone to develop injuries, customarily known as wounds. Although various tissue engineering strategies and bioactive wound matrices have been employed to speed up wound healing, scarring remains a significant challenge. The wound environment is harsh due to the presence of degradative enzymes and elevated pH levels, and the physiological processes involved in tissue regeneration operate on distinct time scales. Therefore, there is a need for effective drug delivery systems (DDSs) to address these issues. The objective of this review is to provide a comprehensive exposition of the mechanisms underlying the skin healing process, the factors and materials used in engineering DDSs, and the different DDSs used in wound care. Furthermore, this investigation will delve into the examination of emergent technologies and potential avenues for enhancing the efficacy of wound care devices.

Integration of Modified Solvay Process for Sodium Bicarbonate Synthesis from Saline Brines with Steelmaking for Utilization of Electric Arc Furnace Slag in CO2 Sequestration and Reagent Regeneration

In the pursuit of sustainable solutions for carbon dioxide CO2 sequestration and emission reduction in the steel industry, this study presents an innovative integration of steelmaking slag with the modified Solvay process for sodium bicarbonate (NaHCO3) synthesis from saline brines. Utilizing diverse minerals, including electric arc furnace (EAF) slag, olivine, and kimberlite, the study explored their reactivity under varied pH conditions and examined their potential in ammonium regeneration. SEM and WDXRF analyses were utilized to acquire morphological and chemical compositions of the minerals. Advanced techniques such as XRD and ICP-OES were employed to meticulously analyze mineralogical transformations and elemental concentrations. The findings demonstrate that steelmaking slag, owing to its superior reactivity and pH buffering capabilities, outperforms natural minerals. The integration of finer slag particles significantly elevated pH levels, facilitating efficient ammonium regeneration. Geochemical modeling provided valuable insights into mineral stability and reactivity, which aligned with the ICP-OES results. This synergistic approach not only aids in CO2 capture through mineral carbonation but also minimizes waste, showcasing its potential as a sustainable and environmentally responsible solution for CO2 mitigation in the steel industry.

Process investigation of ion sorption of complex compounds made by chromium, zinc, nickel and cobalt contained in wastewater bentonite clay

This article outlines the outcomes of laboratory investigations focusing on the sorption behavior of Cr (III, VI), Zn, Ni, and Co on bentonite. The study encompasses a broad spectrum of solution pH levels and sortable component concentrations, aiming to unveil the states of micro-components in aqueous solutions. The research also addresses the identification of optimal chemical concentration conditions and the establishment of a sorption mechanism for these components on clay adsorbents based on bentonite. In aqueous solutions, the ions of these metals undergo hydrolysis, resulting in the formation of complex compounds. The study discerns that the sorption process on bentonite clays predominantly initiates at pH levels around 4-5 and concludes at pH exceeding 7.5-10. These findings shed light on the critical pH ranges where sorption reactions are most significant and highlight the cessation of sorption at elevated pH levels. The research contributes to a comprehensive understanding of the sorption dynamics between bentonite and metal ions, emphasizing the pH-dependent nature of these interactions. By identifying the optimal conditions for sorption and elucidating the underlying mechanisms, this study offers valuable insights into leveraging bentonite clay as an effective adsorbent for the removal of Cr (III, VI), Zn, Ni, and Co from aqueous solutions.

Improving Acid Mine Drainage Treatment through Electrocoagulation: Effect of Time, Electrode Distance, and Electrode Types

This study explores the feasibility of employing electrocoagulation technology to manage Acid Mine Drainage (AMD) wastewater, focusing on reducing heavy metal concentrations, particularly iron (Fe) and manganese (Mn). Samples of AMD liquid waste from PT Lhoong Setia Mining in Aceh Province, Indonesia, underwent electrocoagulation using Al-Zn and Al-Fe electrodes with Direct Current (DC). The investigation considered various parameters, including contact time (ranging from 0 to 45 minutes), electrode distance (2, 2.5, and 3 cm), and electrode type (Al-Fe and Al-Zn). The study revealed that prolonged electrocoagulation increased the reduction of Fe and Mn metals due to enhanced Al(OH)3 formation. While Al-Zn electrodes exhibited rapid coagulant formation initially, Al-Fe electrodes sustained effectiveness throughout the process. Optimal reduction of Fe and Mn concentrations occurred at different electrode distances, emphasizing the critical role of spacing in electrocoagulation efficiency. Furthermore, the electrocoagulation process successfully elevated pH levels within acceptable limits and effectively reduced Total Suspended Solids (TSS) in AMD waste, aligning with regulatory standards. This research underscores the potential for electrocoagulation as a viable technology for mitigating the environmental impact of AMD and addresses knowledge gaps related to efficient pollutant removal in mining wastewater treatment. Future studies should explore parameter optimization and consider transitioning to continuous operation for increased effectiveness, particularly in remote mining locations.

Study of the Properties of Iron/Iron Redox Flow Batteries

New energy storage technologies are needed to offset the erratic power supply of renewable energy sources due to the rising global energy demand and the urgency of climate change action. Even if there are still concerns with operational parameters and efficiency, the Iron/Iron redox flow battery is a viable contender for large-scale energy storage. Iron is a highly affordable active material, making it possible to create inexpensive energy storage systems and possibly batteries with very low initial investment costs due to the positive electrode's moderate pH and relatively low voltage, maintaining minimal toxicity and aggression. Many challenges have been faced in the experiments on iron/iron redox flow batteries. For example, hydrogen formation and its impacts on the system must be minimized to ensure long-term use as an energy storage device. Iron hydroxides quickly form in response to elevated pH levels or contact with ambient oxygen, which restricts the battery's effectiveness.For each series, various iron/iron redox flow batteries were assembled, and their functional properties were studied as a sustainability factor. The functional properties of the battery, such as an increase in electrolyte volume, an increase in charge/discharge times, the addition of a break time between charge/discharge cycles, varied charge cut-off voltages, varied discharge cut-off voltages and IU charge/discharge were investigated. It was also possible to complete more than 50 cycles with 8 hours of charging time and calculate and compare efficiencies and other performance values. The 8 hours of charge/discharge parameter proved to be the most suitable for conducting long-term cycling experiments because of the increased CE and EE trendline over 25 cycles. The 60 minutes rest time recorded a delay of charge voltage with a maximum of 35 minutes starting from the third cycle because of the blockage of the membrane and polarization effects. An optimized battery achieved up to 62% energy efficiency at 25 mA/cm2 with 4 hours of charging time and 8.01 Ah maximum theoretical capacity. Figure 1

Benchmarking the impact of nickel filler addition, weld hardness, environmental pH, and corrosion inhibitors on A333 carbon steel pipe weld corrosion

This study addresses the challenge of preferential weld corrosion in ASTM A333 carbon steel piping, investigating the intricate interplay of various factors. The welding process induces microstructural alterations, making affected areas more prone to corrosion, resulting in Preferential Weld Corrosion (PWC). While the addition of 1 % nickel filler shifts the galvanic potential of Weld Metal (WM), its impact on PWC is marginal due to the high rates of its intrinsic corrosion. Notably, nickel filler addition accelerates corrosion in the heat-affected zone (HAZ). In carbon dioxide (CO2) environments, the presence of acetic acid (HAc) intensifies corrosion; yet, the application of morpholine as pH neutralizer effectively counters its effects. Imidazoline based corrosion inhibitor prove successful in PWC mitigation, particularly at elevated pH levels. Furthermore, Post Weld Heat Treatment (PWHT) significantly reduces hardness, aligning with a decrease in corrosion. Of paramount importance, this study not only examining the effects of individual factors, including microstructure, pH adjustment, corrosion inhibitors, and PWHT, but also scrutinizing their combined impacts. The integration of PWHT with pH adjustment and inhibitor injection yields corrosion rates below 0.1 mm/y, ensuring a remarkable 30-year service life even under challenging conditions. This study underscores the necessity of a comprehensive strategy, combining these factors, to effectively manage preferential weld corrosion in carbon steel weldments.

Increases in Cellular Immune Responses Due to Positive Effect of CVC1302-Induced Lysosomal Escape in Mice.

This study found a higher percentage of CD8+ T cells in piglets immunized with a CVC1302-adjuvanted inactivated foot-and-mouth disease virus (FMDV) vaccine. We wondered whether the CVC1302-adjuvanted inactivated FMDV vaccine promoted cellular immunity by promoting the antigen cross-presentation efficiency of ovalbumin (OVA) through dendritic cells (DCs), mainly via cytosolic pathways. This was demonstrated by the enhanced levels of lysosomal escape of OVA in the DCs loaded with OVA and CVC1302. The higher levels of ROS and significantly enhanced elevated lysosomal pH levels in the DCs facilitated the lysosomal escape of OVA. Significantly enhanced CTL activity levels was observed in the mice immunized with OVA-CVC1302. Overall, CVC1302 increased the cross-presentation of exogenous antigens and the cross-priming of CD8+ T cells by alkalizing the lysosomal pH and facilitating the lysosomal escape of antigens. These studies shed new light on the development of immunopotentiators to improve cellular immunity induced by vaccines.

Degradation of ciprofloxacin using magnetite nanoparticle-activated periodate: Kinetic, mechanistic and toxicity evaluation

In this study, the activation mechanisms of periodate (IO4−) by magnetite (Fe3O4) were investigated for the degradation of ciprofloxacin (CIP). Compared to standalone IO4− (PI) and Fe3O4, the combined Fe3O4/IO4− system exhibited superior degradation efficiency, especially at elevated pH levels, such as 11. Scavenger experiments revealed IO3· and IO4· as critical radicals at pH 6.5, while ·OH was the key reactive species at pH 11. X-ray photoelectron spectroscopy (XPS) identified electron transfer between Fe(II)/Fe(III) species as the main mechanism resulting in the partial reduction of Fe3O4. The study confirmed the high thermal stability of periodate and found that N2 purging reduced the degradation efficiency of the Fe3O4/PI system. High degradation efficiency was maintained in real wastewater and tap water, with Fe3O4 showing minimal structural and performance changes during repeated oxidation processes. Its magnetic properties allow for easy collection and reuse, thus minimizing costs and environmental harm. Liquid chromatography high-resolution mass spectrometry (LC-QTOF-MS) identified CIP degradation products and degradation pathways at different pH values (i.e., 3, 6.5, and 11), with piperazine ring opening and decarboxylation as the main mechanisms. Ecological Structure Activity Relationships (ECOSAR) predicted low acute and chronic toxicity to fish, daphnids and green algae for most CIP degradation products. Overall, the Fe3O4/IO4− systemoffers an efficient alternative for treating effluents containing CIPacross various water media.

Effects of lactic acid bacteria-derived fermented feed on the taste and quality of duck meat

The present study aimed to examine the impact of lactic acid bacteria- fermented feed (FF) on the taste and quality of duck meat, in addition to elucidating the potential metabolomic mechanism at play. The findings revealed that ducks fed with FF exhibited elevated pH levels and reduced cooking loss in their meat when compared to the control group. In addition, the sensory evaluation and e-tongue analysis revealed that the tenderness, juiciness, umami, richness, saltiness, and sweetness of duck meat were all enhanced by feeding FF. Moreover, an examination of the metabolome using 1H nuclear magnetic resonance (1H NMR) identified the principal differential metabolites that exhibited a correlation with taste, which included 2-aminoadipate, glucose, glycine, N-acetylcysteine, niacinamide, proline, and threonine. Furthermore, the differential metabolites that exhibited the greatest enrichment in duck meat could be primarily traced to glutathione metabolism, glycine, serine and threonine metabolism, taurine and hypotaurine metabolism. The potential factors contributing to the effect of FF and basic commercial duck feed (CF) were found to be primarily regulated via the aforementioned metabolic pathways. The study, therefore, offers a viable approach for enhancing the taste and quality of duck meat.

Heterobimetallic Base Pair Programming in Designer 3D DNA Crystals.

Metal-mediated DNA (mmDNA) presents a pathway toward engineering bioinorganic and electronic behavior into DNA devices. Many chemical and biophysical forces drive the programmable chelation of metals between pyrimidine base pairs. Here, we developed a crystallographic method using the three-dimensional (3D) DNA tensegrity triangle motif to capture single- and multi-metal binding modes across granular changes to environmental pH using anomalous scattering. Leveraging this programmable crystal, we determined 28 biomolecular structures to capture mmDNA reactions. We found that silver(I) binds with increasing occupancy in T-T and U-U pairs at elevated pH levels, and we exploited this to capture silver(I) and mercury(II) within the same base pair and to isolate the titration points for homo- and heterometal base pair modes. We additionally determined the structure of a C-C pair with both silver(I) and mercury(II). Finally, we extend our paradigm to capture cadmium(II) in T-T pairs together with mercury(II) at high pH. The precision self-assembly of heterobimetallic DNA chemistry at the sub-nanometer scale will enable atomistic design frameworks for more elaborate mmDNA-based nanodevices and nanotechnologies.

Unveiling the crucial role of iron mineral phase transformation in antimony(V) elimination from natural water

Antimony (Sb) in natural water has long-term effects on both the ecological environment and human health. Iron mineral phase transformation (IMPT) is a prominent process for removing Sb(V) from natural water. However, the importance of IMPT in eliminating Sb remains uncertain. This study examined the various Sb–Fe binding mechanisms found in different IMPT pathways in natural water, shedding light on the underlying mechanisms. The study revealed that the presence of goethite (Goe), hematite (Hem), and magnetite (Mag) significantly affected the concentration of Sb(V) in natural water. Elevated pH levels facilitated higher Fe content in iron solids but impeded the process of removing Sb(V). To further our understanding, polluted natural water samples were collected from various locations surrounding Sb smelter sites. Results confirmed that converting ferrihydrite (Fhy) to Goe significantly reduced Sb levels (<5 μg/L) in natural water. The emergence of secondary iron phases resulted in greater electrostatic attraction and stabilized surface complexes, which was the most likely cause of the decline of Sb concentration in natural water. The comprehensive findings offer new insights into the factors governing IMPT as well as the Sb(V) behavior control.

Adsorption of Heavy Metals from Contaminated Water using Leachate Modular Tower

The heavy metals (HMs) and metalloids such as Cr(VI), As(Ill), and Pb(II) in contaminated water are toxic even at trace levels and have caused devastating negative health impacts on human beings. Hence, the effective adsorption of these heavy metals from contaminated water is important to protect biodiversity, hydrosphere ecosystems, and human beings. In this study, a leachate modular tower (LMT) was developed for the singular purpose of adsorbing HMs. The LMT contained nano-slag as a liner, which was synthesized from slag. The nano-slag was blended in different proportions of 90:10; 80:20, 70:30, 60:40, and 50:50 to the combined mass of clay and nano-slag, to evaluate the most efficient ratio of the blends capable of adsorbing HMs and metalloids with 100% efficiency. A series of leachate tests were performed to evaluate the adsorption capacity of LMT with different embedded liners. Attenuation periods of 2, 5, 7, and 10 days with a temperature of 500 °C were also selected to improve the sorption rate and uptake of HMs. Subsequently, the effluents were subjected to inductive coupled plasma mass spectrometry (ICP-MS) tests to evaluate the concentrations and percentages of adsorbed HMs, which were calculated using a pseudo-first-order adsorption model. The results revealed that the removal of 98%As, 99%Cd, and 99.9% Pb was achieved with a 50%:50% ratio of soil and nano-slag as the liner at 10 days equilibrium period. Furthermore, 98%Zn, 95.45%Cu, 93.3%Fe, 97%Ni, and 89% Hg were achieved upon further investigation using the same dosage of soil and nano-slag and equilibrium conditions. The scanning electron microscopy (SEM) tests demonstrated that some traces of the absorbed HMs and metalloids were found on the liner surfaces, indicating significant changes in microstructure. The results indicated the sorption rate increased significantly due to the elevated temperature, aluminosilicate structure, and prolonged attenuation period, which are also associated with an elevated pH level and higher cation exchange capacity (CEC), of the liner. Doi: 10.28991/CEJ-2023-09-06-017 Full Text: PDF

Simulated Gastric Acid Promotes the Horizontal Transfer of Multidrug Resistance Genes across Bacteria in the Gastrointestinal Tract at Elevated pH Levels.

The assessment of factors that can promote the transmission of antibiotic resistance genes (ARGs) across bacteria in the gastrointestinal tract is in great demand to understand the occurrence of infections related to antibiotic-resistant bacteria (ARB) in humans. However, whether acid-resistant enteric bacteria can promote ARG transmission in gastric fluid under high-pH conditions remains unknown. This study assessed the effects of simulated gastric fluid (SGF) at different pH levels on the RP4 plasmid-mediated conjugative transfer of ARGs. Moreover, transcriptomic analysis, measurement of reactive oxygen species (ROS) levels, assessment of cell membrane permeability, and real-time quantitative assessment of the expression of key genes were performed to identify the underlying mechanisms. The frequency of conjugative transfer was the highest in SGF at pH 4.5. Antidepressant consumption and certain dietary factors further negatively impacted this situation, with 5.66-fold and 4.26-fold increases in the conjugative transfer frequency being noted upon the addition of sertraline and 10% glucose, respectively, compared with that in the control group without any additives. The induction of ROS generation, the activation of cellular antioxidant systems, increases in cell membrane permeability, and the promotion of adhesive pilus formation were factors potentially contributing to the increased transfer frequency. These findings indicate that conjugative transfer could be enhanced under certain circumstances in SGF at elevated pH levels, thereby facilitating ARG transmission in the gastrointestinal tract. IMPORTANCE The low pH of gastric acid kills unwanted microorganisms, in turn affecting their inhabitation in the intestine. Hence, studies on the factors that influence antibiotic resistance gene (ARG) propagation in the gastrointestinal tract and on the underlying mechanisms are limited. In this study, we constructed a conjugative transfer model in the presence of simulated gastric fluid (SGF) and found that SGF could promote the dissemination of ARGs under high-pH conditions. Furthermore, antidepressant consumption and certain dietary factors could negatively impact this situation. Transcriptomic analysis and a reactive oxygen species assay revealed the overproduction of reactive oxygen species as a potential mechanism by which SGF could promote conjugative transfer. This finding can help provide a comprehensive understanding of the bloom of antibiotic-resistant bacteria in the body and create awareness regarding the risk of ARG transmission due to certain diseases or an improper diet and the subsequent decrease in gastric acid levels.

Larval habitat stability and productivity in two sites in Southern Ghana

BackgroundMosquito larval source management (LSM) is a valuable additional tool for malaria vector control. Understanding the characteristics of mosquito larval habitats and its ecology in different land use types can give valuable insight for an effective larval control strategy. This study determined the stability and productivity of potential anopheline larval habitats in two different ecological sites: Anyakpor and Dodowa in southern Ghana.MethodsA total of 59 aquatic habitats positive for anopheline larvae were identified, and sampled every two weeks for a period of 30 weeks using a standard dipping method. Larvae were collected using standard dippers and were raised in the insectary for identification. Sibling species of the Anopheles gambiae sensu lato (s.l.) were further identified by polymerase chain reaction. The presence of larval habitats, their stability and larvae positive habitats were compared between the two sites using Mann–Whitney U and the Kruskal–Wallis test. Factors affecting the presence of An. gambiae larvae and physicochemical properties at the sites were determined using multiple logistic regression analysis and Spearman’s correlation.ResultsOut of a total of 13,681 mosquito immatures collected, 22.6% (3095) were anophelines and 77.38% (10,586) were culicines. Out of the 3095 anophelines collected, An. gambiae s.l. was predominant (99.48%, n = 3079), followed by Anopheles rufipes (0.45%, n = 14), and Anopheles pharoensis (0.064%, n = 2). Sibling species of the An. gambiae consisted of Anopheles coluzzii (71%), followed by An. gambiae s.s. (23%), and Anopheles melas (6%). Anopheles mean larval density was highest in wells [6.44 (95% CI 5.0–8.31) larvae/dip], lowest in furrows [4.18 (95% CI 2.75–6.36) larvae/dip] and man-made ponds [1.20 (95% CI 0.671–2.131) larvae/dip].The results also revealed habitat stability was highly dependent on rainfall intensity, and Anopheles larval densities were also dependent on elevated levels of pH, conductivity and TDS.ConclusionThe presence of larvae in the habitats was dependent on rainfall intensity and proximity to human settlements. To optimize the vector control measures of malaria interventions in southern Ghana, larval control should be focused on larval habitats that are fed by underground water, as these are more productive habitats.Graphical