Plate Count Research Articles

ITO-Coated Vertical Nanowires-Based Biosensors for the Label-Free Detection of Escherichia coli

A major concern in public health is the direct in-situ detection of pathogenic bacteria in food, beverages, and the air [1]. This study utilizes ITO-coated vertical nanowires (ITO-VNWs) as sensing substrates for the detection of Escherichia coli (E. coli). The innovation in this research lies in the direct detection of various concentrations of E. coli using boronic acid (BA)-modified ITO-VNWs connected to a benchtop E4980A precision LCR meter. Impedance spectra were expressed in terms of real and imaginary parts, corresponding to resistance (R) and reactance (X). Serial dilutions of E. coli were prepared in saline for bacterial enumeration and tested using the standard plate count method. Subsequently, 100 μl of each bacterial dilutions (107, 106, 105, 104, 103, 102, and 101 CFU/ml) were applied to BA-modified ITO-VNWs. In summary, BA-modified ITO-VNWs demonstrated accurate and distinct detection of varying concentrations of E. coli. This accomplishment highlights the promising potential of our BA-modified ITO-VNW biosensor for precise bacterial detection across diverse applications. Further exploration and optimization of this platform could lead to advancements in the rapid and specific identification of pathogenic bacteria, making it an invaluable tool in the realm of public health and environmental safety. REFERENCES [1] A. Ahmed, J.V. Rushworth, N.A. Hirst, P.A. Millner, Biosensors for whole-cell bacterial detection, Clin Microbiol Rev 27(3) (2014) 631-46. Figure 1

Effectiveness of Bamboo Stick Liquid Smoke (Bamboo sp.) With Methanol Extract of Sengon Twig Wood (Falcataria moluccana) as a Disinfectant

Pathogenic microorganisms that cause infectious diseases are widely spread in the environment, especially in public places that allow microorganisms to multiply. Disinfectants are used to prevent the spread of these microorganisms. The use of chemical-based disinfectants can cause side effects, so it is necessary to look for alternatives from natural materials, such as a mixture of bamboo stem liquid smoke and methanol extract from Sengon twig wood. The purpose of this study was to determine the effectiveness of a mixture of bamboo stem liquid smoke and methanol extract of Sengon twig on bacteria and fungi. This research method began with an inhibition test of the disc and well diffusion method with five comparison treatments (50:50, 40:60, 30:70, 20:80, 10:90) to obtain the most effective comparison of the volume of 100% bamboo stem liquid smoke mixture and 11% sengon twig wood methanol extract, then tested using the Total Plate Count (TPC) method with swab samples on wooden tables. The results showed that the most effective comparison of the volume of 100% bamboo stem liquid smoke mixture and 11% sengon twig wood methanol extract was the volume ratio of 50:50 from the results of the inhibition zone on Salmonella typhimurium with a diameter of 10.3 mm. The results of the mixed effectiveness test with a ratio of 50:50 with the swab test on the table showed a decrease in the number of bacteria (51%) and fungi (65%). This shows that the mixture of bamboo stem liquid smoke and methanol extract of Sengon twig wood is effective as a disinfectant.

Utilization of roasted barley (Hordeum vulgare) and oat (Avena sativa) for the development of functional yogurt with special reference to storage stability

ABSTRACT The objective of the current study prepare yogurt enriched with roasted barley and oat flour in different treatments. The manual cleaning of oats and barley was carried out and placed in a traditional sand roaster with an iron pan at 280 ± 5°C for 20 seconds. Roasted barley and oat flours were used in different concentrations of 1:0; 3:0; 5:0; 0:1; 0:3; 0:5; 0.5:0.5; 1.5:1.5; and 2.5:2.5 g/100 g, respectively. The prepared yogurt was stored for 28 days at 4°C, and analyzed during the 7-day intervals. The results showed that roasted barley and oat flours contained higher concentrations of proteins (13.72 & 16.61%) and fibers (16.86 & 3.54%), which aided in the improvement of the properties of yogurt. The pH of the prepared yogurt was decreased (4.5 to 4.2), and titratable acidity was increased (0.61 to 0.70%) non-significantly in all treatments. The syneresis rate was decreased (25 to 19%) with increased concentrations of roasted barley and oats during storage. The microbial analysis of the fortified yogurt decreased the total plate count and total yeast count. Concludingly, roasted barley and oats improved the solid contents along with proteins, fats, and fiber contents of the prepared yogurts, improving the nutritional value of yogurt.

Synergistic effects of chitosan and gamma irradiation on enhanced fungal growth inhibition and biodegradability of natural rubber latex film

Developing novel formulations and processes to improve the fungal growth inhibition and biodegradability of NR products has become a major challenge for the scientific community, given the health risks associated with fungi in natural rubber (NR) products and the environmental concerns regarding NR waste. Consequently, this study comprehensively investigated the synergistic effects of chitosan and gamma irradiation on enhancing fungal growth inhibition and biodegradability in natural rubber latex (NRL) films. The research involved incorporating varying chitosan contents (0, 3, 6, or 9 phr) into NRL composites and exposing them to different gamma doses (0, 5, 10, or 15 kGy). The results showed that increasing the chitosan content and the gamma dose improved the ability of the NRL samples to inhibit fungal growth on their surfaces. This was evidenced by the absence of fungal colonies after 7 days of incubation on potato dextrose agar (PDA) plates for NRL samples irradiated at 5–15 kGy with 9 phr of chitosan. This determination was based on isolating fungi from the film surfaces, followed by serial dilution and a viable plate count. The biodegradability tests also revealed that the NRL films irradiated at 15 kGy with 9 phr of chitosan had the highest weight loss, reaching as high as 10.42 ± 0.62 % after soil burial for 8 weeks. However, the results indicated that gamma irradiation on the pristine NRL and chitosan/NRL films did not substantially alter the thermal stabilities, density, morphology, and functional groups of the samples. Lastly, by comparing the tensile properties of all the NRL films to the ASTM D3578-01a standard for examination gloves, the optimum conditions for the NRL films were 5 kGy of gamma irradiation with 9 phr of chitosan. This combination resulted in gloves with sufficient tensile strength and complete fungal growth inhibition.

Sensitivity analysis of parameters on carbon dioxide desorption processes from aqueous monoethanolamine solution

AbstractCarbon dioxide (CO2) capture technologies are crucial for mitigating climate change, with post‐combustion capture (PCC) using chemical absorption being a leading method. However, the energy‐intensive solvent regeneration process presents a significant challenge, consuming up to 50% of the total energy in carbon sequestration. Despite extensive research on absorption, desorption studies remain limited. This study focuses on the desorption analysis through experimental runs in a pilot‐scale tray column with varying flow rates, validating an Aspen Plus model. The research compares the impact of the number of stages, feed stage position, column pressure, and reflux ratio between equilibrium and rate‐based models. The findings reveal enhanced desorption efficiency through optimized operational conditions, including reduced flow rates, additional equilibrium stages, feeding stage positioning closer to the condenser, elevated pressures, and lower reflux ratios. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Tartrate-resistant acid phosphatase (TRAP/ACP5) promotes bone length, regulates cortical and trabecular bone mass, and maintains growth plate architecture and width in a sex- and site-specific manner in mice

Tartrate-resistant acid phosphatase (TRAP) serum levels reflect osteoclast number, bone remodeling activity, and fracture risk. Deletion or loss of function of TRAP results in short stature in mice and man. Yet, the impact and mechanisms of TRAP for the site- and sex-specific development of bone and cartilage is not well understood. Here, we use a global TRAP knockout (TRAPKO) and wildtype littermate control (WT) mice of both sexes to investigate TRAP as a possible sex- and site-specific regulator of bone and growth plate development. TRAPKO mice of both sexes weighed less and had shorter tibial length than their WT, features that were more accentuated in male than female TRAPKO mice. These changes were not associated with a general reduction in growth as not all organs displayed a proportionally lower mass, and serum IGF-1 was unchanged. Using μCT and site-specificity analysis of the cortical bone revealed wider proximal tibia, a higher trabecular thickness, and lower trabecular separation in male TRAPKO compared to WT mice, an effect not seen in female mice. Histomorphometric analysis revealed that the growth plate height as well as height of terminal hypertrophic chondrocytes were markedly increased, and the number of columns was decreased in TRAPKO mice of both sexes. These effects were more accentuated in female mice. Proliferation and differentiation of bone marrow derived macrophages into osteoclasts, as well as C-terminal cross links were normal in TRAPKO mice of both sexes. Collectively, our results show that TRAP regulates bone and cartilage development in a sex-and site-specific manner in mice.

The mesostructure evolution of cemented paste backfill during mixing

Mixing plays a crucial role in preparing Cemented Paste Backfill (CPB). Shearing, concentration, and particle size distribution are key factors that impact the flow of CPB slurry. This study employed focused beam reflectance measurement and a torque sensor to monitor the flow and structure evolution of CPB during the mixing process. The mixing process can be divided into three stages based on the torque curve: aggregation, destruction, and equilibrium. The structural evolution is the cause of the flow of fresh CPB. Each stage exhibits distinctive characteristics of the fresh CPB. During the aggregation stage, coarse tailings agglomerate via liquid bridges, binders agglomerate by hydration, and fine tailings interact mostly due to interparticle forces. Since the network is heterogeneous, the structure cannot resist shearing forces during the destruction and equilibrium stages. Finally, a rheological model was developed based on the mesostructure evolution mechanism of CPB.

Effect of hot air-assisted radio frequency rotation heating system on improving heating uniformity of dried black fungus (Auricularia auricula)

A large-capacity radio frequency (RF) rotation heating system was employed in this study to heat dried black fungus, and hot air was used for assistance treatment. The effects of electrode gap, rotation rate and hot air on the uniformity of RF heating of dried black fungus were explored. The optimal heating process parameters were obtained, and the sterilization effect was validated. The results showed that the rotation system could significantly enhance the RF heating uniformity of black fungus (P > 0.05). The optimal heating process for heating a large-capacity (480 g) black fungus was to utilize RF heating assisted by 70 °C hot air with an electrode gap of 175 mm and a rotation rate of 60 rpm, followed by 30 min of heat preservation at 70 °C hot air with a rotation rate of 40 rpm. After the entire sterilization treatment, the heating uniformity index λ of black fungus was reduced to 0.027 ± 0.004, the total plate count decreased by 3 log CFU/g, and the moisture content dropped to below 13 %. The ideal RF heating uniformity and sterilization effect of black fungus were obtained in this study through the simultaneous use of hot air and rotation, providing a theoretical foundation for the application of RF technology in the processing of black fungus.

Numerical simulation of wake flow around two square cylinders through passive control method

Two-dimensional numerical simulations are performed to study the effect of height of control plates placed at the downstream location in a vertical direction of a channel for flow past two inline square cylinders. The numerical method used is the lattice Boltzmann method (LBM) and Reynolds number is kept constant at Re = 150 (Re = Uinf d/ν) for fixed gap spacing g = 3.5 (g = s/d). The height of the control plate varies from h = 0.1 to 8. First, the validity of code for the present problem and suitable grid points are checked along the selection of uniform inflow velocity. After that verification, the numerical simulations are performed to obtain the results under the effect of height of control plates using the passive control method. Calculated results are, in terms of vorticity contour, drag and lift coefficients, pressure contour, energy spectrum, and force statistics. Under the discussion of vorticity contour visualization, we obtained six types of flow mode and named them according to flow behavior and their characteristics. In pressure contour, it is visualized that the maximum pressure occurred at near the upstream position of the first cylinder as well as the upper and lower edge of the main cylinder as compared to the downstream cylinder and control plate, but at some position inside the domain, pressure contour contained negative values as well in between the gap of two square cylinders and control plate. In force statistics, we computed the values of Cdmean, Cdrms, Clrms, and St. Mean drag coefficients for both upstream cylinder (C1) and downstream cylinder (C2) are increased as the height of the control plate increased from 0.1 to 1.5, but as the height of the control plate reached its maximum value, the value of Cdmean turned toward the decline. The maximum value of Cdmean obtained at h = 2.25 and the minimum value occurred at h = 8. For cylinder C2, negative values for some selected heights such as h = 0.1–1.25 and h = 4–8 are also observed because of thrust. The value of the Strouhal number for both the cylinders C1 and C2 are similar at h = 0.1–4.5, but at h = 5, the values of the Strouhal number differ for both cylinders, but at the largest values of control plate's height, i.e., h = 6–8, the Strouhal number contains zero values for both cylinders C1 and C2. At these zero values of the Strouhal number, in vorticity contour jet type of flow mode is observed at h = 6–8, as a new flow mode, which is not identified before in the passive control method for flow past two or more square cylinders.

Investigation of vortex-induced vibration of a Π-type bridge girder and its suppression using G-shaped apron combination measure

The Π-type steel-concrete composite girder, a commonly used bridge deck composed of an upper concrete slab and two lower lateral I-side steel girders, often suffers from severe vortex-induced vibrations (VIVs). Herein, the VIV response and triggering mechanism of a Π-type girder are systematically investigated, by adopting 1:50 scale section model wind tunnel tests and flow-field numerical simulations. Afterward, several aerodynamic measures were designed to mitigate the significant VIVs present in the original section, and an effective measure composed of the G-shaped apron and lower central stabilizer plate was found. Numerical simulation results show that the Π-type girder's upper and lower surfaces both exhibit severe vortex shedding, and both contribute significantly to the occurrence of VIVs. Consequently, the aerodynamic measures introduced for the Π-type girder must be able to simultaneously improve the flowing bypassing situation around the upper and lower surfaces of the section, and the G-shaped apron and the lower central stabilizer plate could both accomplish this simultaneously. The results show that the VIV suppression effect of this G-shaped apron combination measure is greatly affected by the height of the G-shaped apron's vertical plate and the height of the lower central stabilizer plate. Only both of them to a certain height, this measure can entirely prevent the Π-type girder from VIVs. After shape optimization, a G-shaped apron combination aerodynamic measure that can eliminate completely the Π-type girder's VIVs at low damping ratios of about 0.5% is proposed, of which the vibration-suppressing effect was verified by wind tunnel testing of 1:20 section model.

Study on the synthesis of nanoparticles and their power characteristics in a bubble liquid membrane reactor

Abstract A bubble liquid film reactor is a new type of reactor used for preparing nanoparticles, which has strong inflation ability and dispersion, homogenization, and emulsification effects, especially suitable for preparing loose nanoparticles. In the actual production of enterprises, there is an urgent need to expand production capacity and scale up the reactor. Due to the lack of power characteristic data during the reaction process, it is difficult to select the motor, resulting in unnecessary energy and cost waste. Therefore, the power characteristic data of bubble liquid film reactors urgently needs to be studied. This article investigates the influence of operating conditions such as bubble cap diameter and immersion depth on stirring power and obtains the power characteristics during the operation of a bubble liquid film reactor. The results indicate that the larger the diameter of the bubble cap disk, the stronger the power consumption, but the smaller the power input capacity. The deeper the immersion depth, the higher the power consumption and the stronger the power input capability. Finally, fitting the dimensionless power standard formula provides a mathematical model for reactor amplification, providing theoretical guidance for enterprises to expand production lines and increase production capacity, and providing data support for motor selection.

Responses analysis and structural optimization of a semisubmersible platform based on the Taguchi experiment method

Responses analysis and structural optimization of a semisubmersible platform based on the Taguchi experiment method

Antimicrobial photodynamic therapy against Escherichia coli by exploiting endogenously produced Protoporphyrin IX- In vitro study.

Due to antimicrobial drug resistance, there is a growing interest in the development of light based alternative antibacterial therapies. This research work is focused on the inactivation of Escherichia coli (E. coli) by exploiting the absorption bands 405, 505, 542, 580 and 631nm of its indigenously produced Protoporphyrin IX (PpIX) excited by three LEDs with broad emission bands at 418, 522 and 630nm and two laser diodes with narrow emission bands at 405 and 635nm. Fluorescence spectroscopy and plate count method have been employed for studying the inactivation rate of E. coli strain in autoclaved water suspension. It has been found that LEDs at 418, 522 and 630nm produced pronounced antimicrobial photodynamic effect on E. coli strain comparing laser diodes at 405 and 635nm, which might be attributed to the overlapping of broad emission bands of LEDs with the absorption bands of PpIX than narrow emission bands of laser diodes. Particular effect of LED at 522nm has been noticed because its broad emission band overlaps three absorption bands 505, 542 and 580nm of PpIX. The gold standard plate count method strongly correlates with Fluorescence spectroscopy, making it an innovative tool to administer bacterial inactivation. The experimental results suggested the development of a light source that entirely overlap absorption bands of PpIx to produce a pronounced antimicrobial photodynamic effect, which might become an effective modality for in vivo disinfection of antibiotic resistant microbes in wounds and lesions.

Presence of Pathogenic Bacteria in School Children's Snack Food Samples in Medan City

Purpose: Good and healthy food must be free from harmful and toxic substances, such as microbial contamination, chemicals, and other materials. The term School Children's Snack Food (PJAS) is a food that is found and routinely consumed by children in the school environment, food must meet the requirements of microbial contamination limits based on SNI (Indonesian National Standard) safety testing. The cause of food poisoning that is still a serious problem in various countries including Indonesia is pathogenic bacteria. The purpose of this study is to determine the presence of pathogenic bacteria in school children's snack food samples in Medan City in the Pematangsiantar area. Methodology: The methods used were the Nearest Approximate Count (JPT) of Escherichia coli, Bacillus sp. Number Test, Staphylococcus sp. Number Test, Salmonella Identification, and Total Plate Count (TPC). Findings: The test results on JPT Escherichia coli fried meatballs include SD M (9.9 ± 3.8) MPN/g, SD 5 (8.68 ± 2.73) MPN/g, SD IT (5.08 ± 0.66) MPN/g, and SD 4 (4.26 ± 2.44) MPN/g. The results of JPT Escherichia coli in fried meatballs in SD 1 and SD 2, as well as JPT E. coli ojek in all elementary schools, namely < 3 MPN/g. Significance: Conclusion that the snack food for elementary school children (fried and fried meatballs) in Pematangsiantar did not contain contamination with pathogenic bacteria Escherichia coli, Bacillus sp., Staphylococcus sp., Salmonella, and Total Plate Count (TPC).

Variability in Maize Seed Bacterization and Survival Correlating with Root Colonization by Pseudomonas Isolates with Plant-Probiotic Traits.

Seed treatment with plant growth-promoting bacteria represents the primary strategy to incorporate them into agricultural ecosystems, particularly for crops under extensive management, such as maize. In this study, we evaluated the seed bacterization levels, root colonization patterns, and root competitiveness of a collection of autochthonous Pseudomonas isolates that have demonstrated several plant-probiotic abilities in vitro. Our findings indicate that the seed bacterization level, both with and without the addition of various protectants, is specific to each Pseudomonas strain, including their response to seed pre-hydration. Bacterization kinetics revealed that while certain isolates persisted on seed surfaces for up to 4 days post-inoculation (dpi), others experienced a rapid decline in viability after 1 or 2 dpi. The observed differences in seed bacterization levels were consistent with the root colonization densities observed through confocal microscopy analysis, and with root competitiveness quantified via selective plate counts. Notably, isolates P. protegens RBAN4 and P. chlororaphis subsp. aurantiaca SMMP3 demonstrated effective competition with the natural microflora for colonizing the maize rhizosphere and both promoted shoot and root biomass production in maize assessed at the V3 grown stage. Conversely, P. donghuensis SVBP6 was detected at very low levels in the maize rhizosphere, but still exhibited a positive effect on plant parameters, suggesting a growth-stimulatory effect during the early stages of plant development. In conclusion, there is a considerable strain-specific variability in the maize seed bacterization and survival capacities of Pseudomonas isolates with plant-probiotic traits, with a correlation in their root competitiveness under natural conditions. This variability must be understood to optimize their adoption as inputs for the agricultural system. Our experimental approach emphasizes the critical importance of tailoring seed bacterization treatments for each inoculant candidate, including the selection and incorporation of protective substances. It should not be assumed that all bacterial cells exhibit a similar performance.

Antibacterial effect of ethanolic Gnetum gnemon L. leaf extract on food-borne pathogens and its application as a natural preservative on raw quail eggs

Gnetum gnemon L. is an evergreen tree that belongs to the Gnetaceae family and is commonly used as a vegetable and medicinal plant among indigenous people. The key goal of this study was to assess the antibacterial efficacy of ethanolic G. gnemon leaf extract (EGLE) against six food-borne pathogens. The antimicrobial activity of EGLE was evaluated using multiple methods, including the well diffusion assay (WDA), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assay. Gas Chromatography-Mass Spectrometry (GC-MS) analysis was used to identify active volatile compounds responsible for EGLE's antibacterial activities. Total plate count (TPC) was conducted to measure microbial populations and evaluate the efficacy of EGLE as a natural preservative in raw quail eggs. 100 g of dried and powdered sample yielded an average of 11.58 ± 0.38 % post-extraction. The inhibition zone in WDA ranged from 11.00 ± 0.57–13.50 ± 0.58 mm, MIC ranged from 6.25 to 50.00 mg/mL, and MBC values were between 12.5 and >50 mg/mL. Results from the time-kill study showed that at 4 × MIC Bacillus pumilus and B. megaterium were completely killed in 1 h incubation time and other bacteria were killed within 2–4 h. Findings from TPC demonstrated that at the highest tested concentration of EGLE, there was no significant bacterial growth for a 30-day observation period. Thereby, suggesting that it had the potential to function as a natural preservative for raw quail eggs. EGLE may be a viable alternative to synthetic preservatives in combating food-borne pathogens.

Antimicrobial Potential of Strontium-Functionalized Titanium Against Bacteria Associated With Peri-Implantitis.

To explore the antimicrobial potential of strontium (Sr)-functionalized wafers against multiple bacteria associated with per-implant infections, in both mono- and multispecies biofilms. The bactericidal and bacteriostatic effect of silicon wafers functionalized with a strontium titanium oxygen coating (Sr-Ti-O) or covered only with Ti (controls) against several bacteria, either grown as a mono-species or multispecies biofilms, was assessed using a bacterial viability assay and a plate counting method. Mono-species biofilms were assessed after 2 and 24 h, while the antimicrobial effect on multispecies biofilms was assessed at Days 1, 3, and 6. The impact of Sr functionalization on the total percentage ofPorphyromonas gingivalis in the multispecies biofilm, using qPCR, and gingipain activity was also assessed. Sr-functionalized wafers, compared to controls, were associated with statistically significant less viable cells in both mono- and multispecies tests. The number of colony forming units (CFUs) within the biofilm was significantly less in Sr-functionalized wafers, compared to control wafers, for Staphylococcus aureus at all time points of evaluation and forEscherichia coli at Day 1. Gingipain activity was less in Sr-functionalized wafers, compared to control wafers, and the qPCR showed that P. gingivalis remained below detection levels at Sr-functionalized wafers, while it consisted of 15% of the total biofilm on control wafers at Day 6. Sr functionalization displayed promising antimicrobial potential, possessing bactericidal and bacteriostatic ability against bacteria associated with peri-implantitis grown either as mono-species or mixed in a multispecies consortium with several common oral microorganisms.

Exploring the In-Vitro anti-oxidant and anti-microbial properties of pomelo fruit extract in goat meat: A promising alternative for preservative and health benefits

This study investigates the potential nutritional benefits of pomelo fruit (Citrus maxima) and its application in preserving complex food matrices, focusing on its antioxidant and antimicrobial properties. The in vitro antioxidant activities of pomelo fruit extract (PFE) was evaluated using various assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, H2O2 scavenging, reducing power, and total phenolic content analysis. Additionally, the antimicrobial activity of PFE was assessed against E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella Typhi. The study further examined the preservation quality of minced goat meat during refrigeration storage (4 ± 1 ºC) for 15 days by treating it with varying concentrations (0.1 %, 0.5 %, 1 %, 3 %, and 5 %) of PFE (15 % v/w). Changes in physico-chemical and microbial properties were analyzed. The results revealed a significant (P < 0.05) increase in the antioxidant and antimicrobial efficacy of PFE with increase in concentrations. Moreover, the addition of PFE (up to 5 %) effectively reduced pH, thiobarbituric acid reactive substances (TBARS), peroxide levels, free fatty acids, and microbial load (total plate count and coliform count) in goat meat (P < 0.05) during refrigeration storage. Importantly, the sensory quality of the meat remained unaffected by the addition of PFE (up to 1 %). These findings highlight the abundant presence of antioxidants and antimicrobials in PFE, suggesting its potential as a natural preservative for complex meat matrices. The study demonstrates that the undesirable effects of prolonged storage on goat meat quality can be mitigated by incorporating PFE (up to 1 %), without compromising sensory attributes.

Antimicrobial impact of a propolis/PVA/chitosan composite and its prospective application against methicillin resistance bacterial infection

Seriously damaged skin could be infected by methicillin-resistant bacteria, which delays restoration. Propolis has bioactivity linked with its minor components, such as antimicrobials and antioxidants. Active sites in polyvinyl alcohol (PVA) and chitosan (CS) can enhance the nano-loading of natural extracts with activity amelioration. Korean propolis extract (KPE) loading to a nanocomposite possibly enhances its antimicrobial and anti-inflammatory potency. Composites were formed using two PVA/CS structures (1:1; 2:1), and their skin-application appropriateness was determined by mechanical properties, moisture content, water activity, and color. The composite of PVA/CS (1:1) was more practicable for KPE-loading. Increasing KPE concentrations (50, 100, 150, and 200 ng/mL) alters composite bioactivity measured by Fourier transmission infrared (FT-IR). Antibacterial potency of 200 ng KPE/mL was the most effective concentration, followed by 150 ng KPE/mL, against Staphylococcus aureus (MRSA) and Clostridium perfringens. The composite activity was measured as minimum inhibition (MIC) and minimum bacterial concentrations (MBC). At 200 ng KPE/mL, MIC and MBC against MRSA were 14.93 ± 1.21 and 20.21 ± 1.97 mg composite/mL, respectively. Significant inhibition was also recorded for antibiofilm formation, where MRSA growth was not detected after 4 hours of time intervals to the stainless-steel coupon. Compared to planktonic bacteria, the formed barrier of PVA/CS restrained the biofilm matrix formation and supported KPE antimicrobial. The impact of inhibition against biofilm formation depends on two parallel mechanisms (PVA barrier with hydrogen bonds, besides nano-KPE particle penetration into bacterial cells). The KPE-composite application to rats’ wounds shows significantly reduced MRSA infection. The results demonstrate the capability of KPE composite in reducing infection, healing correctly, and restoring hair. The wound swabbed test emphasizes this capacity, in which bacterial growth rate restriction was evaluated using a plate count assay. The results recommended 150 ng KPE/mL loading into CS/PVA (1:1) as an effective anti-pathogenic treatment, particularly against the MRSA infection of wounds.

Groot Aub groundwater quality and its suitability for domestic purposes, Namibia

The Groot Aub (GA) settlement depends entirely on groundwater for domestic purposes and other development activities. Development activities are mainly agriculture, such as animal husbandry, chicken farming and crop farming using irrigation. However, these activities have the potential to contaminate the groundwater system. A total of 87 groundwater samples were collected from the boreholes in the study area during the dry and wet season. Water quality parameters (pH, salinity, total dissolved solids (TDS), electrical conductivity (EC) and hydrochemistry (Na+ &gt; Ca2+ &gt; Mg2+ &gt; K+, and HCO3− &gt; SO42− &gt; Cl−) of 5 boreholes and 1 reservoir tank were analysed. The dominant cations were attributed to cation exchange processes as a coupled exchange of Na+ + K+ replacing Ca2+; and Na+ replacing Mg2+ ions in the rock–water interactions. The HCO3− anion is attributed to underlying rich carbonate rocks in the study area and chemical reactions between groundwater and silicate minerals. TDS ranged from 639.01 to 1 998.96 mg/L. The microbial levels as indicated by heterotrophic plate count (HPC) values exceed the limits imposed by the local Namibian and WHO drinking water regulations. The Piper diagrams showed a mixed water type of mainly HCO3− and SO42− anions and Na+ and Ca2+ &gt; Mg2+ cations. The study shows that the elemental composition of the groundwater is impacted significantly by primarily anthropogenic activities and secondarily geogenic processes. Based on the results of this study it is recommended that a buffer zone be created between human activities and production boreholes to avoid further groundwater contamination.