Inhibition Zone Diameter Research Articles

Antibacterial effects of children's and adults' toothpastes containing different amounts of fluoride: An in vitro study.

In recent years, fluoride concentrations in toothpaste for children and adults have increased. However, the effects of different concentrations on bacterial activity have rarely been compared. We aimed to investigate and compare the antibacterial activity of children's and adults' toothpaste containing 500, 1000‒1100, and 1450‒1500 ppm fluoride. Three strains of bacteria (Streptococcus mutans, Streptococcus salivarius, and Lactobacillus casei) were cultured in brain heart infusion agar. Thirty commercially available toothpaste products for children and adults containing 500, 1000‒1100, and 1450‒1500 ppm fluoride were selected and tested. Toothpaste's ability to inhibit bacterial growth was evaluated by agar diffusion assay, in which plates were incubated for 24 hours, and then the diameter of the microbial inhibition zone was measured. Comparisons between children's and adults' fluoride toothpastes were made using the Mann-Whitney U test. The association between bacterial growth inhibition and sodium lauryl sulfate (SLS) was analyzed by the chi-square test. A P value of <0.05 was considered statistically significant. No difference in the inhibition zone was observed for different fluoride concentrations. However, there were significant differences between toothpastes for children and adults, with higher inhibition zones for adults' toothpastes. Most toothpastes for adults contained SLS, which was associated with antibacterial activity. Fluoride concentrations ranging from 500 to 1500 ppm did not affect bacterial growth. The antibacterial activity of toothpastes for adults was significantly higher than that of toothpastes for children, which was mainly attributed to the SLS usually added to adult formulations.

Extension of ultrafiltered cheese shelf life using edible coatings containing supercritical rosemary, thyme and coriander extracts as antimicrobial agents

Currently, supercritical extraction allows for the “green” isolation of plant antimicrobial components and their subsequent use in the food industry. The study aims to extend the shelf life of ultrafiltered cheese by using edible coatings containing supercritical fluid extracts (SFEs) of Rosmarinus officinalis L., Thymus vulgaris and Coriandrum sativum L. The SFEs chemical profiling was studied using GC-MS. Ten emulsion coating formulations were prepared using whey protein concentrate and the SFEs. The antimicrobial activity of coatings was assessed using well diffusion assay. Their effect on shelf life, physicochemical and sensory characteristics of the ultrafiltered cheese samples was investigated. GC/MS analysis of Rosmarinus officinalis L., Thymus vulgaris and Coriandrum sativum L. showed that 1,8-Cineol, m-Cymene, and Linalool are the major compounds with 35.4, 41.6, and 61.3 % respectively. The particle size of all formulations ranged from 157.3 to 453.7 nm and had a broad size distribution with a low Polydispersity Index values ranging from 0.35 to 0.49. The obtained Zeta potential values from −27.8 to −36.0 mV indicate the stability of the SFE-emulsion formulations. The antimicrobial trials showed that formulations, that mainly contained Thymus vulgaris, demonstrated more inhibition effect against all tested strains than other formulas with inhibition zone diameter ranged between 10.7 and 16.3 mm and followed by formulations, that mainly contained Rosmarinus officinalis L., with inhibition zones diameter between 6.7 and 11.7 mm depending on microbial type. Combining rosemary and coriander extracts synergistically enhanced their antimicrobial effect and extended the shelf life of cheese beyond 40 days.

Pullulan-Tween 40 emulsified films containing geraniol: production and characterization as potential food packaging materials

Petroleum-based plastics have been widely used as packaging materials because of their low-cost availability and good mechanical properties. However, the use of plastics has become restricted as they are highly resistant to biodegradation, causing environmental problems. This work aimed to produce and characterize emulsified pullulan films incorporating geraniol for application as food packaging materials with potential to substitute the conventional plastics. When geraniol was incorporated in the films, they showed antimicrobial activity against Enterococcus faecalis ATCC 29212 (inhibition zone diameter = 15.19 ± 0.66 mm) and Pseudomonas aeruginosa ATCC 27853 (inhibition zone diameter = 10.99 ± 1.82 mm). Furthermore, scanning electron microscopy showed the inhibition of Enterococcus faecalis ATCC 29212 biofilms when they were directly formed on the emulsified pullulan films incorporating geraniol. The produced films also demonstrated high transparency (> 90%) and hydrophilic surfaces (water contact angle < 90°). This work demonstrated the viability of using geraniol to produce pullulan active films as new food packaging materials.

Green fabrication of ZnO nanoparticles via spirulina platensis and its efficiency against biofilm forming pathogens

Excessive consumption of antibiotics is considered one of the top public health threats, this necessitates the development of new compounds that can hamper the spread of infections. A facile green technology for the biosynthesis of Zinc oxide nanoparticles (ZnO NPs) using the methanol extract of Spirulina platensis as a reducing and stabilizing agent has been developed. A bunch of spectroscopic and microscopic investigations confirmed the biogenic generation of nano-scaled ZnO with a mean size of 19.103 ± 5.66 nm. The prepared ZnO NPs were scrutinized for their antibacterial and antibiofilm potentiality, the inhibition zone diameters ranged from 12.57 ± 0.006 mm to 17.33 ± 0.006 mm (at 20 µg/mL) for a variety of Gram-positive and Gram-negative pathogens, also significant eradication of the biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae by 96.7% and 94.8% respectively was detected. The free radical scavenging test showed a promising antioxidant capacity of the biogenic ZnO NPs (IC50=78.35 µg/mL). Furthermore, the anti-inflammatory role detected using the HRBCs-MSM technique revealed an efficient stabilization of red blood cells in a concentration-dependent manner. In addition, the biogenic ZnO NPs have significant anticoagulant and antitumor activities as well as minimal cytotoxicity against Vero cells. Thus, this study offered green ZnO NPs that can act as a secure substitute for synthetic antimicrobials and could be applied in numerous biomedical applications.

ISOLATION OF LACTIC ACID BACTERIA FROM VANAME SHRIMP (Litopenaeus vannamei) AND ITS ANTAGONISM TO PATHOGEN BACTERIA

Vaname shrimp is one of Indonesia's leading export species and is widely cultivated. The main problem in vaname shrimp pond cultivation is the attack of shrimp diseases caused by bacteria or viruses. This study aims to isolate and identify lactic acid bacteria (BAL) from vaname shrimp (Litopenaeus vannamei) and test their antagonism against pathogenic bacteria. The research was conducted from February to April 2023. The method used in this study is a survey method. Sampling was conducted at the vaname shrimp pond of the Fisheries Service Task Unit (UPT), Tanjung Punak Village, Rupat Utara District, Bengkalis Regency, Riau. The method used in this research was a survey method. BAL was isolated using MRS Agar + CaCO3 media. The Kirby-Bauer method was used to test bacterial antagonism against pathogenic bacteria. Based on the identification of seven isolates, it was found that only four isolates were positively identified as LAB bacteria, namely 47D, 54T1, 73DB1, and 73BD2. The results of the antagonism test against pathogenic bacteria showed that all BAL isolates could not suppress the growth of E. coli bacteria. However, these isolates suppressed the growth of A. hydrophila bacteria, with the widest inhibition zone diameter on isolate 54T1 (4.2 mm). On Vibrio sp. bacteria, the widest inhibition zone of BAL was on isolate 73DB1 (6 mm). These results indicate that the antibacterial activity produced by BAL is still relatively weak

Sodium Alginate–Soy Protein Isolate–Chitosan–Capsaicin–Nanosilver Multifunctional Antibacterial Composite Gel

We constructed a sodium alginate/soy protein isolate/chitosan gel system and incorporated silver nanoparticles reduced by capsaicin into the system, forming a sodium alginate–soy protein isolate–chitosan–capsaicin–silver nanoparticle composite gel (SA/SPI/CTS/CAP/Ag). In tests, the SA/SPI/CTS/CAP/Ag gel exhibited excellent antimicrobial properties. Using the agar diffusion method, the inhibition zone diameter for Staphylococcus aureus was determined to be 29.5 mm. Soy protein isolate (SPI), containing a large number of hydrophobic amino acid residues, effectively enhanced the moisture retention capability of the gel and improved its stability to a certain extent at an appropriate addition concentration. In a milk preservation experiment, the SA/SPI/CTS/CAP/Ag gel significantly extended the shelf-life of the milk. In dye adsorption experiments, the adsorption curve of the SA/SPI/CTS/CAP/Ag gel well fitted a pseudo-second-order kinetic model. It showed a degree of adsorption capacity for methylene blue, malachite green, methyl orange, and Congo red, with the most significant adsorption effect for malachite green being 42.48 mg/g. Considering its outstanding antimicrobial performance, preservation ability, and adsorption capacity, the SA/SPI/CTS/CAP/Ag gel holds significant potential in wastewater treatment and as an antimicrobial gel in the exploration of food preservation.

Synthesis and antibacterial activity of metallic copper‐chitosan nanomaterial using environmentally friendly Cleistocalyx operculatus leaf extract as a reducing agent

AbstractThe copper‐chitosan nanomaterial (CuNPs‐CTS) was effectively produced through a chemical reduction process employing Cleistocalyx operculatus leaf extract (COLE) as a reduction agent and chitosan as a stabilization agent. Both COLE and chitosan were derived from natural sources and are environmentally friendly. Various techniques including XRD, SEM, TEM, and DLS were used to characterize the samples. The findings revealed the exclusive presence of CuNPs metal when COLE was used as the reducing agent, while the presence of both metallic Cu and Cu2O was the result of using NaBH4. The CuNPs‐CTS material synthesized with COLE displayed CuNPs particles with diameters varying from 10 to 30 nm. CuNPs‐CTS materials were tested for their antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. CuNPs‐CTS materials effectively inhibited the growth of these bacteria, significantly expanding the bacterial inhibition zone compared to the control sample (distilled water). The CuNPs‐CTS material using COLE exhibited a bacterial inhibition zone diameter of around 20 and 18 mm against S. aureus and E. coli, respectively. This surpassed the antibacterial performance of the CuNPs‐CTS material employing NaBH4 against S. aureus (18 mm).

Corynebacterium diphtheriae and Corynebacterium ulcerans: development of EUCAST methods and generation of data on which to determine breakpoints.

Evidence-based clinical susceptibility breakpoints have been lacking for antimicrobial agents used for diphtheria. We aimed to evaluate broth microdilution and disc diffusion methods and create a dataset of MIC values and inhibition zone diameters (ZDs) from which breakpoints could be determined. We included 400 recent clinical isolates equally distributed by species (Corynebacterium diphtheriae and Corynebacterium ulcerans) and by national surveillance programmes (France and Germany). Non-duplicate toxigenic and non-toxigenic isolates were chosen to enable the inclusion of a diversity of susceptibility levels for the 13 agents tested. Broth microdilution and disc diffusion, using EUCAST methodology for fastidious organisms, were used. The distributions of MIC and ZD values were largely in agreement among methods and countries. Breakpoints to allow categorization of WT isolates as susceptible, i.e. susceptible (S) or susceptible, increased exposure (I) were determined for 12 agents. The data supported a breakpoint for benzylpenicillin and amoxicillin of resistant (R) > 1 mg/L since WT isolates were inhibited by 1 mg/L or less. WT isolates were categorized as I (S ≤ 0.001 mg/L) for benzylpenicillin, emphasizing the need for increased exposure, and S (S ≤ 1 mg/L) for amoxicillin. Erythromycin breakpoints were set at S ≤ 0.06 mg/L and R > 0.06 mg/L. The corresponding ZD breakpoints were determined for all agents except amoxicillin, for which categorization was based on benzylpenicillin results. This work provided a large set of antimicrobial susceptibility data for C. diphtheriae and C. ulcerans, using a harmonized methodology. The dataset allowed EUCAST and experts in the diphtheria field to develop evidence-based breakpoints in January 2023.

Molecular identification of endophytic bacterium DBA2 isolated from the leaf of binahong (Anredera cordifolia (Ten.) Steenis) and its antagonistic activity against bacteria associated with dental caries

Binahong plants (Anredera cordifolia (Ten.) Steenis) are known to contain secondary metabolites which have important biological properties. The current study focused on the endophytic bacteria which lives in the leaves of A. cordifolia (Ten.) Steenis. The aim of this study is to isolate and identify the endophytic bacteria which can produce antibacterial metabolites from the leaves of A. cordifolia (Ten.) Steenis. Two isolates, DBA1 and DBA2 were isolated and purified from the leaves of A. cordifolia. These isolates were subjected to the screening for their antagonistic activity against the bacteria associated with dental caries, which are Streptococcus mutans and Lactobacillus acidophilus using the disk-diffusion method. The strain of DBA2 exhibited the largest diameter of inhibition zone against both S. mutans (31,17 mm) and L. acidophilus (35,57 mm). While DBA1 exhibited the diameter of inhibition zone of 23,47 mm and 25,87 mm against S. mutans and L. acidophilus, as respectively. The strain of DBA2 was then subjected for molecular identification. The genomic DNA of DBA2 was extracted with the Geno Plus™ Genomic DNA Extraction Miniprep System and molecular identification was performed by PCR amplification and sequencing of the 16S rRNA gene. The amplicons were then purified and sequenced, before the 16S rRNA gene sequences were analysed by a Basic Local Alignment Search Tool (BLAST) search against the National Centre Biotechnology Information (NCBI) database. The endophytic bacterial strain DBA2 from the leaves of A. cordifolia was identified to be closely related to Bacillus sp., and the top match from the database search revealed a similarity value of 100% with the reference Bacillus sp. strain x20. Future studies are required to analyse the bioactive compounds of strain DBA2, which can be considered as a potential source for the new antibacterial drugs for the dental caries treatment.

Investigating the in vitro antibacterial efficacy of composite bone cement incorporating natural product-based monomers and gentamicin

ObjectiveThe objective of this study is to investigate the impact of four natural product extracts, namely, aloe-emodin, quercetin, curcumin, and tannic acid, on the in vitro bacteriostatic properties and biocompatibility of gentamicin-loaded bone cement and to establish an experimental groundwork supporting the clinical utility of antibiotic-loaded bone cements (ALBC).MethodsBased on the components, the bone cement samples were categorized as follows: the gentamicin combined with aloe-emodin group, the gentamicin combined with quercetin group, the gentamicin combined with curcumin group, the gentamicin combined with tannic acid group, the gentamicin group, the aloe-emodin group, the quercetin group, the curcumin group, and the tannic acid group. Using the disk diffusion test, we investigated the antibacterial properties of the bone cement material against Staphylococcus aureus (n = 4). We tested cell toxicity and proliferation using the cell counting kit-8 (CCK-8) and examined the biocompatibility of bone cement materials.ResultsThe combination of gentamicin with the four natural product extracts resulted in significantly larger diameters of inhibition zones compared to gentamicin alone, and the difference was statistically significant (P < 0.05). Except for the groups containing tannic acid, cells in all other groups showed good proliferation across varying time intervals without displaying significant cytotoxicity (P < 0.05).ConclusionIn this study, aloe-emodin, quercetin, curcumin, and tannic acid were capable of enhancing the in vitro antibacterial performance of gentamicin-loaded bone cement against S. aureus. While the groups containing tannic acid displayed moderate cytotoxicity in in vitro cell culture, all other groups showed no discernible cytotoxic effects.

Oxidative Stress-Mediated Repression of Virulence Gene Transcription and Biofilm Formation as Antibacterial Action of Cinnamomum burmannii Essential Oil on Staphylococcus aureus.

This work aimed to identify the chemical compounds of Cinnamomum burmannii leaf essential oil (CBLEO) and to unravel the antibacterial mechanism of CBLEO at the molecular level for developing antimicrobials. CBLEO had 37 volatile compounds with abundant borneol (28.40%) and showed good potential to control foodborne pathogens, of which Staphylococcus aureus had the greatest inhibition zone diameter (28.72 mm) with the lowest values of minimum inhibitory concentration (1.0 μg/mL) and bactericidal concentration (2.0 μg/mL). To unravel the antibacterial action of CBLEO on S. aureus, a dynamic exploration of antibacterial growth, material leakage, ROS formation, protein oxidation, cell morphology, and interaction with genome DNA was conducted on S. aureus exposed to CBLEO at different doses (1/2-2×MIC) and times (0-24 h), indicating that CBLEO acts as an inducer for ROS production and the oxidative stress of S. aureus. To highlight the antibacterial action of CBLEO on S. aureus at the molecular level, we performed a comparative association of ROS accumulation with some key virulence-related gene (sigB/agrA/sarA/icaA/cidA/rsbU) transcription, protease production, and biofilm formation in S. aureus subjected to CBLEO at different levels and times, revealing that CBLEO-induced oxidative stress caused transcript suppression of virulence regulators (RsbU and SigB) and its targeted genes, causing a protease level increase destined for the biofilm formation and growth inhibition of S. aureus, which may be a key bactericidal action. Our findings provide valuable information for studying the antibacterial mechanism of essential oil against pathogens.

Antibacterial Effect of Eight Essential Oils against Bacteria Implicated in Bovine Mastitis and Characterization of Primary Action Mode of Thymus capitatus Essential Oil.

During the current investigation, eight essential oils (EOs) were tested for their antimicrobial activity against six species, belonging to the genus of staphylococcus, multi-resistant to antibiotics (S. epidermidis, S. cohni, S. wareneri, S. scuiri, S. chromogenes, S. pasteuri), three methicillin-resistant Staphylococcus aureus strains (MRSA) and two strains of Escherichia coli, producing extended-spectrum β-lactamase (ESBL) responsible for bovine mastitis. Our results indicated that the antimicrobial activities of eight EOs varied significantly among the types of EOs and bacterial species. Thymus capitatus and Trachyspermum ammi EOs display important antibacterial activity against all tested strains, with the inhibition zone diameters situated between 20 and 45 mm, while EOs of Artemisia absinthium, Eucalyptus globulus, Eucalyptus camaldulensis, Myrtus communis and Mentha pulegium exerted an intermediate activity. For Cymbopogon citratus, this effect depends on bacteria species. In fact, an important effect was observed against S. warneri, S. epidermidis, S. cohenii, S. pasteuri and MRSA (EC 39+) strains. In addition, the important lytic effect was observed against MRSA strains, showing that Gram-positive bacteria were more sensitive to T. capitatus EO than Gram-negative ones. Concerning the characterization of the mode action of T. capitatus, experiments of kill-time, bacteriolytic, loss of salt tolerance and loss of cytoplasmic material showed that the used EO was able to destroy cell walls and membranes followed by the loss of vital intracellular materials. In addition, it inhibits the normal synthesis of DNA, causing the bacterial death of E. coli and MRSA strains. This study shows the potential of using of EOs, particularly T. capitaus, to inhibit the growth of Gram-positive and Gram-negative bacteria multi-resistant to antibiotics causing bovine mastitis.

Potent biological activity of newly fabricated silver nanoparticles coated by a carbon shell synthesized by electrical arc

Highly effective AgNPs@C was efficiently synthesized by electrical arc powered by single spark unit which was sufficient to ionize the dielectric media (deionized water) through applying strong electric field between the electrodes (silver and carbon). The AgNPs@C shell was characterized in terms of stability, morphology and phase structure. All characterizations showed that the prepared silver nanoparticles were spherical with average size reached 17 nm coated with carbon shell. The antibacterial effect of the synthesized nanoparticles was tested against Pseudomonas aeruginosa in comparison to Ceftazidime (commonly used antibiotic against P. aeruginosa infections). It was revealed that AgNPs@C shell has superior activity with inhibition zone diameter reached 15 mm and minimum inhibitory concentration reached 2 µg/mL. The observed activity was further confirmed by confocal microscope which showed an increased red region, representing the dead cells, correlated with the presence of AgNPs@C. Moreover, transmission electron microscope studies implied the possible AgNPs@C antibacterial mechanism of action was the nanoparticles adherence to the bacterial membrane causing cell lysis. The molecular studies against fimH (virulence adhesion gene), rmpA (mucoid factor encoding gene), and mrkA (biofilm forming gene) proved the inhibition of their genetic expression. The cytotoxic effect of the synthesized AgNPs@C showed CC50 reached 235.5 μg/mL against normal lung cells (L929 cell line).

Optimization of Synthesis Reaction Parameters of AgNPs Derived from Laser trilobum Plant for Foodborne Pathogens

In this study, the antimicrobial activity of silver nanoparticles (AgNPs L21, AgNPs L22) produced using aqueous extracts of the Laser trilobum harvested in 2021 and 2022 was optimized. The experimental design and optimization of antimicrobial activity were performed using the response surface method (RSM). Using RSM, independent variables, such as silver concentration, extraction time, and synthesis temperature, were optimized as a result of the inhibition zone diameter against Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes. Based on the optimization results, the extraction time, silver concentration, and temperature for AgNP L21 and L22 synthesis were determined to be 60 min, 5 mM, and 25 °C, respectively. When the XRD and TEM results of the nanoparticles synthesized under optimal conditions were evaluated, it was determined that the AgNPs were spherical in shape and had an average size of 30 ± 12 nm. Our study revealed that the year of harvest is unimportant for nanoparticles synthesized from L. trilobum, using a cheap and simple method that does not require toxic substances. Owing to the antimicrobial activity of nanoparticles produced under optimal conditions, it is possible to biocontrol and prevent contamination by these bacteria in food science and industry.

Comparative study of volatile oil constituents, anti-microbial properties, and antibiofilm activities in Eucalyptus camaldulensis and Eucalyptus globulus: insights from central Saudi Arabia

Eucalyptus is a fragrant plant with a highly volatile oil content grown worldwide. This study investigated the phytochemical and biological features of two Eucalyptus species, E. camaldulensis and E. globulus, cultivated in Central Saudi Arabia. Phytochemical analysis revealed 17 compounds in E. camaldulensis and 13 in E. globulus, with α-pinene and 1,8-cineole being both plants’ most abundant volatile components. The antimicrobial activity revealed that Salmonella typhimurium ATCC 13311 and Candida albicans ATCC 10231 are the most susceptible to E. camaldulensis, with the zone of inhibition diameters (ZIDs) of 17.0 ± 0.2 mm and 22.0 ± 0.3 mm, respectively. In contrast, for E. globulus, methicillin-resistant Staphylococcus aureus and Candida albicans ATCC 10231 were the most susceptible, with ZIDs of 13.0 ± 0.2 mm and 20.0 ± 0.2 mm, respectively. E. camaldulensis had minimum inhibitory concentration (MIC) range from 1.56 to 12.5 μL/mL, minimum biocidal concentration (MBC) range from 3.125 to 25.0 μL/mL, minimum biofilm inhibitory concentration (MBIC) range from 3.125 to 25.0 μL/mL, and minimum biofilm eradication concentration (MBEC) from 6.25 to 50.0 μL/mL, while E. globulus had MIC range from 3.125 to 12.5 μL/mL, MBC range from 6.25 to 25.0 μL/mL, MBIC range from 6.25 to 25.0 μL/mL, and MBEC range from 12.5 to 50.0 μL/mL, for the tested organisms. E. camaldulensis demonstrated better antimicrobial activity than E. globulus against the tested organisms, making it a promising antimicrobial drug candidate. Further research is required to determine its effectiveness in treating different human infections.

FcLR-Chitosan/Pullulan nanofibers: Boosted antibacterial activity and decreased cytotoxicity

Natural and environmentally benign electrospun polymeric nanofibers (NFs) with distinctive features, unique physiochemical and biological properties, and high susceptibility to carry non-toxic antibacterial cargoes, e.g., ferrocenyl-based compounds, have emerged as a neo-tool for killing bacteria. Here, the antibacterial FcLR-Chit/Pull NFs were fabricated through three steps: 1) synthesis of FcLR-Chit via the attachment of chitosan to Ferrocenyl Lawesson’s Reagent (FcLR), 2) blending of the FcLR-Chit at various concentrations with the natural polymer of pullulan, and 3) electrospinning. The successfully characterized FcLR-Chit/Pull NFs with a homogenous distribution of FcLR-Chit inside the pullulan matrix were thermally stable up to 270–290 ºC and mechanically stable with an increased elongation at break (EAB) (30.0–42.2%) and decreased tensile strength (TS) (1.1–2.3 MPa) compared to the pure pullulan NFs with the EAB of 19.0% and TS of 3.6 MPa. Pure pullulan NFs and FcLR-Chit/Pull NFs (0.1 wt%, 1.0 wt%, and 5.0 wt%) showed insignificant cytotoxicity on the fibroblast cell lines (L929). The antibacterial activity was detected in the trend of FcLR-Chit/Pull NFs (5.0 wt%)>FcLR-Chit powder (5.0 wt% in water)>FcLR-Chit/Pull NFs (1.0 wt%)>FcLR powder (5.0 wt% in water)>FcLR-Chit/Pull NFs (0.1 wt%)>chitosan powder (5.0 wt% in water)> pure pullulan NFs. The FcLR-Chit/Pull NFs (5.0 wt%) with an average diameter of 365 nm, insignificant cytotoxicity on L929 cells within 24 h and 48 h, and boosted antibacterial activity with the inhibition zone diameter of 1.95 mm against Gram-negative E. Coli and 1.76 mm against Gram-positive S. aureus bacteria were chosen as the optimal nanofibrous candidate for the future bactericidal applications.

Effect of Co-Surfactants on Properties and Bactericidal Activity of Cu2O and Hybrid Cu2O/Ag Particles.

Nanomaterials based on metal oxides, especially Cu2O, have received much attention in recent years due to the many unique properties of the surface plasmon resonance they provide. The report presented the co-precipitation method, a simple preparation method to produce Cu2O oxide particles. In addition, to improve the unique antibacterial properties of Cu2O, a proposed method is to attach Ag nanoparticles to the surface of Cu2O particles. The Cu2O and Cu2O-Ag particles were synthesized based on redox reactions using ascorbic acid (LAA) as a reducing agent. Moreover, in this experiment, two surfactants, polyethylene glycol 6000 (PEG 6000) and sodium dodecyl sulfate (SDS), were added during the manufacturing process to create particle samples and particle combinations with better properties than the original sample. Changes in the characteristics and properties of particle samples are determined by many different physical and chemical methods such as ultraviolet-visible spectroscopy (UV-Vis), infrared spectroscopy (IR), noise X-ray radiation (XRD), scanning electron microscope (SEM), dynamic light scattering (DLS), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). Finally, the activity against bacteria, including E. coli and S. aureus, was also tested using the agar well diffusion method to determine the zone of inhibition. The results improved the particle size value, which decreased by half to 200 nm when two additional surfactants, PEG and SDS, were added. In addition, the antibacterial ability has also been shown to increase significantly when the diameter of the bacterial inhibition zone increased significantly, reaching values of 20 mm (Cu2O/Ag/SDS) and 32 mm (Cu2O/Ag/PEG) for the E. coli bacterial strain. The initial test sample was only about 14 mm in size. The S. aureus bacterial strain also had a similar improvement trend after adding Ag to the Cu2O surface with the appearance of two surfactants, SDS and PEG. The inhibition zone diameter values reached the optimal value at 36 mm in the Cu2O/Ag/PEG particle combination sample compared to only the initial 26 mm in the Cu2O particle sample. Finally, the particle samples are added to the acrylic emulsion paint film to evaluate the changes. Positive results were obtained, such as improvement in adhesion (1.22 MPa), relative hardness (240/425), and sand drop resistance (100 L/mil) in the Cu2O/Ag/PEG particle combination sample, which showed the correctness and accuracy of the research.

Antimicrobial and Antioxidant Activities of Ethanolic Extract of Fermented Black Sesame (Sesamum indicum L.) Seed Dregs

Sesame seed dregs or residue refers to the byproduct that is left after sesame seeds have been processed to extract oil and can used in a variety of ways. The residues were subjected to spontaneous fermentation for 7 days at room temperature (23-27°C). The purpose of this research was to analyze antimicrobial and antioxidant activity of ethanolic extract obtained from fermented black sesame seed dregs. The diameter of inhibition zones of extracts against 16 pathogenic microorganisms ranged from 6.88 to 11.00 mm and the minimum inhibitory concentrations ranged from 6.25 to 50.00 mg/mL, with the extract being particularly effective against P. aeruginosa ATCC9027 and C. albicans ATCC10231. Minimum bactericidal/fungicidal concentrations were spread from 25.00 to &gt;50.00 mg/mL. P. aeruginosa ATCC9027 and C. albicans ATCC10231 were completely killed in 2 h incubation time at 4 × MIC in a time-kill kinetics assay. In comparison to raw seeds and seed dregs extracts, the fermented seed dregs extract displayed a higher total phenolic content. In addition, the fermented extract had a lower IC50 concentration compared to raw seeds and seed dregs extracts. These results suggest that fermented black sesame seed dregs can be used as an alternative method to reduce the microorganism’s growth. This is crucial for ensuring food safety and minimizing the risk of foodborne poisoning.

Determination of the chemical composition and evaluation of the antimicrobial and antioxidant potential of the essential oil from Cryptocarya ovalifolia van der Werff leaves (Lauraceae)

The present work aims to evaluate the chemical composition, the antimicrobial and antioxidant properties of the essential oil from Cryptocarya ovalifolia van der Werff (COEO) leaves collected in Mandraka forest. COEO was extracted by steam distillation from fresh leaves, with a yield of 0.7%. COEO appeared as a clear liquid, yellow, with a pleasant odour and relative density of 0.8943 at 20 °C, a refractive index of 1.4746, an optical rotation of – 31°13, an acid index of 0.638 and an ester index of 6.375. A total of 31 constituents accounting for 99.98% of the total essential oil content were identified by gas chromatography/mass spectrometry. The main component was sabinene (30.65%) and the major components (&gt;5%) were limonene (17.33%), methyleugenol (14%) and α-pinene (8.33%). The antibacterial activity was tested on nine pathogenic microorganisms including four Gram positive bacteria, four Gram negative bacteria and one yeast using the disk diffusion and the microdilution assays. COEO was active on 4 strains with inhibition zone diameter (IZD) ranging from 8.7 mm (Bacillus cereus) to 12.7 mm (Clostridium perfringens). Minimum Inhibitory Concentration (MIC) varied from 1.12 to 2.23 mg/ml and Minimum Bactericidal Concentration (MBC) was 8.93 mg/ml for all strains. COEO had bacteriostatic action on Streptococcus pneumoniae, Clostridium perfringens, Bacillus cereus and Candida albicans (MBC/MIC&gt;4) and bactericidal action on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi and Vibrio fischeri (MBC/MIC≤4). COEO exhibited radical scavenging activity against DPPH with an IC50 of 123.29 mg/ml. By oral route, its LD50 was 1.9/Kg body weight.

Antibacterial activity and mechanism of cell-free supernatants of Lacticaseibacillus paracasei against Propionibacterium acnes

Propionibacterium acnes (P. acnes) is an anaerobic and gram-positive bacterium involved in the pathogenesis and inflammation of acne vulgaris. This study particularly focuses on the antimicrobial effect of Lacticaseibacillus paracasei LPH01 against P. acnes, a bacterium that causes acne vulgaris. Fifty-seven Lactobacillus strains were tested for their ability to inhibit P. acnes growth employing the Oxford Cup and double dilution methods. The cell-free supernatant (CFS) of L. paracasei LPH01 demonstrated a strong inhibitory effect, with an inhibition zone diameter of 24.65 ± 0.27 mm and a minimum inhibitory concentration of 12.5 mg/mL. Among the CFS, the fraction over 10 kDa (CFS-10) revealed the best antibacterial effect. Confocal laser scanning microscopes and flow cytometry showed that CFS-10 could reduce cell metabolic activity and cell viability and destroy the integrity and permeability of the cell membrane. A scanning electron microscope revealed that bacterial cells exhibited obvious morphological and ultrastructural changes, which further confirmed the damage of CFS-10 to the cell membrane and cell wall. Findings demonstrated that CFS-10 inhibited the conversion of triglycerides, decreased the production of free fatty acids, and down-regulated the extracellular expression of the lipase gene. This study provides a theoretical basis for the metabolite of L. paracasei LPH01 as a potential antibiotic alternative in cosmeceutical skincare products.