Agar-well Diffusion Assay Research Articles

Development and Evaluation of the Antibacterial Properties of an Experimental Herbal Gel Against Cariogenic Bacteria.

Recently, products with antibacterial properties derived from medicinal plants have increased as an alternative to conventional drugs. Thus, this study aimed to formulate and evaluate the antibacterial activity of an experimental gel based on Grindelia tarapacana essential oil in a bacterial consortium. The composition of the essential oil (EO) was determined using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of the EO against Streptococcus mutans ATCC 25175, Streptococcus sanguinis ATCC 10556, and Streptococcus salivarius ATCC 13419 was evaluated using an Agar disc diffusion and minimum inhibitory concentration methods. Five formulations of the experimental gel were prepared at 0.25%, 0.5%, 1%, 1.5%, and 2% (v/v). The antibacterial susceptibility test was evaluated using an Agar-Well diffusion assay against a bacterial consortium of S. mutans, S. sanguinis, and S. salivarius. The physical properties, pH, spreadability, gel morphology, phase separation, and drug release were evaluated. The experimental gels were compared with a chlorhexidine gel. Data were analyzed with one-way ANOVA and Kruskal-Wallis tests with a significant level of 5%. The major components of the EO were bornyl acetate, α-isomethyl-E-nerolidol, germacrene B, E-nerolidol, α-cedrene-epoxide, fokienol, and 10-epi-γ-eudesmol. All formulations were effective in inhibiting bacterial growth. The 2% concentration presented inhibition zones (18.14 ± 1.01 mm) similar to those observed for the chlorhexidine gel (p > 0.05). All formulations were stable, without signs of separation, with adequate physical properties, and no significant differences were observed regarding the drug content with the chlorhexidine gel (p > 0.05). The experimental gels based on G. tarapacana EO presented good physicochemical properties and were highly effective in inhibiting the growth of a cariogenic bacterial consortium.

Self-assembled sustainable bionanocomposite hydrogels from chitosan for the combination chemotherapy of hydrophobic and hydrophilic drugs.

Self-assembled hydrogels derived from naturally sourced polymers have gained significant interest in drug delivery applications, owing to their potential, exceptional biocompatibility and sustainable properties. This work presents the development and application of self-assembled nanocomposite hydrogels from chitosan and nanosilver as a pH responsive drug delivery system for the controlled release of doxorubicin and paclitaxel in anticancer therapy. Chitosan was functionalized with 4-formyl benzoic acid for incorporating both hydrophobic and hydrophilic anticancer drugs. The self-assembled nanocomposite hydrogels formed from chitosan and 4-formyl benzoic acid by various non-covalent interactions were studied by FT-IR, Dynamic Light Scattering (DLS), and rheology analysis. Rheology studies demonstrated the hydrogel's shear-thinning nature, enabling easy injection. The antibacterial activity can be evidenced by agar-well diffusion assay and MIC values were measured. The antibacterial effect was analyzed by agar-well diffusion assays and H2-DCFDA assay, providing a comprehensive understanding. In-vivo pharmacokinetic studies on Wistar rats demonstrated promising and effective systemic circulation of drug loaded material in blood, thus supporting its potential for therapeutic applications. All these studies and results demonstrates feasibility and a novel synergistic dual drug delivery approach, promising the synergy between hydrophobic paclitaxel (PTX) and hydrophilic Doxorubicin hydrochloride (Dox.HCl), for improved anticancer efficacy.

Antibiotic-Producing Bacteria Collected from Seawater

Background: Microorganisms are a known source of antibiotics. The study aimed to identify and screen antibiotic-producing microbes isolated from seawater. Method: Three of the fifty (50) bacteria isolated from seawater showed positive for antibiotic activity. The antimicrobial activity of Pseudomonas guguanensis (KD1) was screened against the ESKAPE pathogens using agar-well diffusion assays. P. guguanensis (KD1) was selected for the fermentation and extraction of antimicrobial compounds using solvent extraction assays. Results: P. guguanensis (KD1) produced the highest antibacterial activity after 36 h of cultivation, inhibiting S. aureus, E. faecium, A. baumannii and E. cloacae. According to sensitization assay, K. pneumoniae was impermeable to all the cell-free supernatants of P. guguanensis (KD1). Using agar-well diffusion assays, ethyl acetate extracts from the supernatant recorded zones of inhibition against S. aureus, E. faecium, and E. cloacae, producing zones of 20.1 ± 0.432, 17.8 ± 0.121 and 16 ± 0.162 mm, respectively. Acetonitrile extract from the supernatant inhibited A. baumannii and S. aureus, forming zones of inhibition 18.2 ± 0.323 mm and 18 ± 0.234. The minimum inhibitory concentration and minimum bactericidal concentration recorded for the ethyl acetate extract and acetonitrile extract ranged from 1.56 to 6.25 mg/mL and 12.5–25 mg/mL, respectively. Conclusions: P. guguanensis (KD1) offers a potential source of antibiotics for infections caused by multidrug-resistant bacteria.

EVALUATING THE BIOLOGICAL ACTIVITIES OF SILVER AND ZINC OXIDE NANOPARTICLES BIOSYNTHESIZED BY NEOWESTIELLOPSIS PERSICA A1387

In this research, the antimicrobial properties of zinc oxide (ZnO NPs) and silver (AgNPs) nanoparticles, synthesized biologically using Neowestiellopsis persica through various methods (such as wet biomass, boiling biomass, supernatant, extracellular polysaccharides, and phycocyanin), were examined against fish pathogens including Aeromonas hydrophila, Edwardsiella tarda, Yersinia enterocolitica, and Pseudomonas putida. The nanoparticles were successfully created using all methods and characterized employing techniques like UV-visible spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The antibacterial activity of the nanoparticles was assessed using agar-well diffusion assays, while transmission electron microscopy (TEM) was utilized to analyze the ultrastructural interactions between the nanoparticles and the pathogens. Cytotoxicity was evaluated via the trypan blue exclusion method. Notably, nanoparticles generated through the boiling-biomass method demonstrated significantly enhanced characteristics. The analysis revealed two distinct populations of AgNPs measuring 78.82 nm (41.2%) and 91.28 nm (45.5%), along with a pronounced absorption peak at 68.6 nm (80.1%) for ZnO NPs. AgNPs exhibited the strongest growth inhibition against Pseudomonas putida and Edwardsiella tarda, whereas ZnO NPs showed the largest inhibition zone against Yersinia enterocolitica, Pseudomonas aeruginosa, and Aeromonas hydrophila. TEM imagery illustrated the binding of nanoparticles to the outer membranes of Yersinia enterocolitica, compromising their structural integrity. The application of 25 µg/ml of AgNPs and 6.25 µg/ml of ZnO did not lead to significant cell death, but higher concentrations resulted in a dose-dependent cytotoxic effect. Ultimately, the findings of this study confirm that the antibacterial and cytotoxic attributes of silver and zinc oxide nanoparticles, produced through the biosynthesis of Neowestiellopsis persica A1387, can be leveraged to meet future needs in aquaculture.

Antibacterial and antioxidant activities of Alcea kurdica flower, leaf and root aqueous and organic extracts

Global concerns are rising due to complications associated with the use of chemical agents and antibiotic resistance. Consequently, research focus has shifted towards the quest for effective agents of biological origin. The aim of the present study was to assess the antioxidant and antimicrobial potentials of aqueous and organic extracts derived from various parts of Alcea kurdica. Different parts of A. kurdica were obtained and prepared into leaf, flower and root powders. The powders were extracted with aqueous and organic solvents. The antimicrobial activity of these extracts was assessed against bacterial pathogens using the agar well-diffusion assay. Additionally, the antioxidant effects of the extracts were evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and resazurin dye scavenging assays. The results showed dose-dependent antibacterial activity against Staphylococcus aureus and Escherichia coli for both the organic and aqueous leaf and floral extracts. Furthermore, an antioxidant effect (>80%) was also observed for the organic and water extracts of the flowers, leaves and roots of the plant at the highest concentration (500 µg/ml), as compared to ascorbic acid, which served as the positive control using both the DPPH and resazurin methods. The findings of this study highlighted that A. kurdica can be considered a rich source of potential antioxidant and antibacterial agents, warranting future investigation to identify its active ingredients.

Screening and evaluation of antibacterial active strains of Actinomycetes isolated from Northern Indian soil for biofilm inhibition against selected ESKAPE pathogens

AbstractThe growing problem of antimicrobial resistance (AMR) globally has warranted the search for new and alternate anti-infective strategies. This study aimed to isolate and screen soil Actinomycetes from three different locations in Northern India for their broad-spectrum antibacterial and antibiofilm activity against certain drug-resistant bacteria from ESKAPE group. A total of 110 isolates of Actinomycetes were screened for antibacterial activity using overlay and agar-well diffusion assay against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Ninety-five isolates showed antibacterial activity against one or more test bacteria. These isolates were tentatively identified as members of genus Streptomyces. Five isolates (IMA13, IMA25, IMA43, IMA46, and IMA47) demonstrated broad-spectrum activity against test pathogens and were subjected to production of secondary metabolites in liquid medium. Ethyl acetate fraction of culture filtrate showed MIC in the range of 64–512 µg/ml against test bacteria. The most active isolate, IMA-46, was identified by 16srRNA gene sequence analysis as Streptomyces rameus. Further, ethyl acetate fraction from S. rameus-IMA46 was used to inhibit biofilm formation at sub-MIC values. A significant level (50% to 92%) of biofilm inhibition was recorded against test pathogens. Light microscopy and SEM analysis revealed the biofilm structural changes, reduction in cell aggregation and EPS production. LC/MS analysis of the active extract of S. rameus IMA46 showed the presence of many biologically active compounds, including tetracycline and doxycycline. The present study highlights the potential of soil Actinomycetes in production of broad-spectrum anti-infective compounds in combating growing problem of AMR.

Therapeutic potential of probiotics to counter Campylobacter infections: An In vitro and In vivo evaluation in mice

Probiotics, including Lactic Acid Bacteria (LAB), have gained considerable attention due to their potential health benefits for humans and animal livestock. This research aimed to isolate probiotic bacteria of human origin and explore their therapeutic potential against Campylobacter strains, which are recognized as the leading bacterial cause of human gastroenteritis worldwide. A collection of 230 LAB isolates from human stools were screened for the ability of cell free supernatants to inhibit the growth of three strains of C. jejuni and a C. coli. Co-culture and agar-well diffusion assays identified seven isolates with inhibitory activity against Campylobacter ssp., which were characterized as probiotic strains by their tolerance to pH 2 and bile salts, and then identified as Enterococcus spp. using 16S rRNA gene sequencing E. faecalis NM231, E. faecium NM234, E. faecium NM233, E. faecium NM113, E. durans NM232, E. faecalis NM235, and E. faecium NM236. In vivo evaluation was undertaken by the oral administration of selected probiotics to groups of mice prior to challenge with C. jejuni. Histopathological examinations showed challenge groups receiving either mixed probiotics or E. faecium NM234 were protected against C. jejuni-induced jejunal, colonic, ovarian and uterine tissue damage. Immunohistochemical detection of the challenged mice revealed the presence of C. jejuni antigen in jejunal, colonic, ovarian and uterine sections but was absent in mice receiving either mixed probiotics or E. faecium NM234. This study introduces E. faecium NM234 as a promising probiotic against Campylobacter.

Exploring Eucalyptus globulus phytochemicals: Analytical, antibacterial, and molecular docking investigations

This study presents a comprehensive investigation into chemical composition, antibacterial activity and molecular interactions of phytocompounds present in Eucalyptus globulus leaf extracts. Gas chromatography-mass spectroscopy analysis was employed to identify and quantify the bioactive compounds present in the extracts. The major phytocompounds are found to be 1,8- cineole, α-pinene and α-guaiene. The antibacterial potential of extracts was evaluated against gram-positive and negative strains using agar well-diffusion assay. The methanolic extract showed more antibacterial activity for Staphylococcus aureus and Escherichia coli strains having inhibition zone of 17.6 ± 0.94 and 21.3 ± 0.47 mm respectively when compared to petroleum ether extracts having zone of inhibition of 13 ± 0.81 and 17.3 ± 0.47 mm respectively for Staphylococcus aureus and Escherichia coli strains. Molecular docking studies provided insights into binding modes and interaction between phytocompounds and bacterial targets. The results shed light on the potential mechanisms of antibacterial action, enhancing our understanding of efficacy of phytocompounds. The ADMET and toxicity studies further validates the phytocompounds as promising candidates for further exploration and development of novel antibacterial agents.

Evaluation of Antimicrobial and Cytotoxic Activity of Nanoformulated Chamomile and Green Tea-Based Mouthwash: An In Vitro Study.

Introduction Nanotechnology plays a significant role in the biomedical and dental fields, offering numerous benefits to humans. Particularly, nanoparticles synthesised through green methods involving herbal formulations present promising advantages. Zinc oxide nanoparticles (ZnONPs)demonstrate strong antibacterial properties. Utilising treatments incorporating chamomile tea and green tea may potentially reduce toxicity while enhancing antibacterial effectiveness against oral infections. This study aimed to develop a mouthwash containing ZnONPs, followed by an evaluation of both its cytotoxicity and antibacterial effectiveness. Materials and methods This study was conducted at Saveetha Dental College, Saveetha Institute of Medical and Technical Science, Chennai, India. In the synthesis of ZnONPs, a formulation consisting of chamomile tea and green tea was employed. Subsequently, these synthesised nanoparticles were used in the preparation of mouthwash. An antimicrobial test of the produced ZnONPs was carried out using the agar well diffusion technique for oral pathogens. For analysis ofcytotoxicity, brine shrimps were used in an assay, and comparisons were made with a commercially available mouthwash. Results The antimicrobial properties were assessed, and the formulated mouthwash demonstrated a zone of inhibition of Staphylococcus aureus (20 mm), Enterococcus faecalis (11 mm), Streptococcus mutans (15 mm)and Candida albicans (13 mm), when the agar welldiffusion assay was carried out.Furthermore, the formulated mouthwash exhibited lower cytotoxicity compared to the commercially available mouthwash when cytotoxicity was checked in brine shrimps. Conclusion In our study, the ZnONPsynthesis with chamomile tea and green tea showed notable antibacterial and antifungal effects. In addition,lower toxicity was observed compared to the commercially available mouthwash. These findings suggest that mouthwash formulated with green-synthesis ZnONPs could serve as a viable alternative to synthetic mouthwash options. As a result, it is suggested that ZnONPs could be employed in mouthwash formulations at concentrations of 40 µL.

A Study to Evaluate the Anti Bacterial Activity of Squilla Maritima Against Streptococcus Pneumonia in - Vitro

This study aims to evaluate the antibacterial properties of Squilla maritima, a homoeopathic medicine, against Streptococcus pneumonia, a common pathogen in the human upper respiratory tract. The Agar Well-Diffusion test will be used to screen the bacteria at 30C and 200C potencies. Result: Squilla maritime 30C (0.8±0.1), 200C (0.6±0.1) cm. showed inhibitory activity against Streptococcus pneumonia by Agar well-diffusion assay. Squilla maritima 30 showed maximum Growth inhibitory zone (GIZ) against Streptococcus pneumonia. But Vehicle control (Dispensing alcohol or ethanol 90%) showed 10mm of Growth inhibitory zone which is more than squilla 30C. Conclusion: This experiment showed that the homoeopathic medicine Squilla maritima has antibacterial property against Streptococcus pneumonia which is less effective than dispensing alcohol.

A Study to Evaluate the Antibacterial Activity of Homoeopathic Medicine Myristica Sebifera Mercurius Iodatus Rubrum Hamamelis Virginica Against Staphylococcus Aureus - in Vitro

Staphylococcus aureus is a Gram-positive, non-moving cocci found in grape-like clusters in the upper respiratory tract and skin. It is a member of the Bacillota and can grow without oxygen. Although it acts commensally, it can also become an opportunistic pathogen, causing skin infections, respiratory infections, and food poisoning. In 1880, Scottish surgeon Alexander Ogston discovered that Staphylococcus can cause wound infections after observing bacteria in pus from surgical abscesses. S. aureus is a common bacteria that can be found on the skin of the host, but most of its carriage occurs through the nasal passages and ears. The purpose of this study is to assess the antibacterial efficacy of the homoeopathic remedies Hamamelis virginica, Myristica sebifera, and Mercurius iodatus ruber against Staphylococcus aureus.As a result, the Agar Well-Diffusion assay is employed to screen the bacteria at 30C, 200C, and 1M potencies. Findings: Myristica sebifera 30C(11) mm, 200C (9 ) mm, 1M (10) mm; Mercurius iodatus ruber 30C (6 ) mm, 200C ( 8 ) mm, 1M ( 7) mm; Hamamelis virginica 30C(3 ) mm, 200C( 4) mm, 1M ( 5) mm; Mercurius sebifera in 1M showed maximum Growth inhibitory zone (GIZ) against Staphylococcus aureus following comparison with Vehicle control (dispensing alcohol or ethanol 90%) and Positive control (Amoxyclavatum).

Antimicrobial Activity of Zinc Oxide Nanoparticles Synthesized Using Ocimum Tenuiflorum and Ocimum Gratissimum Herbal Formulation Against Oral Pathogens.

Background This study deals with the antimicrobial efficacy of zinc oxide nanoparticles (ZnONPs) synthesized through green methods employing extracts from Ocimum tenuiflorum and Ocimum gratissimumand assessed for their antimicrobial properties against a range of oral pathogens. Methods Zinc oxide nanoparticles (ZnONPs) were synthesized using extracts from Ocimum tenuiflorumand Ocimum gratissimumthrough a green synthesis approach. Antimicrobial activity was determined using the agar-well diffusion assay to evaluate the consistency of inhibition zones against oral pathogens. Variations in sensitivity were assessed through the time-kill curve assay, quantifying the response of oral pathogens to zinc oxide nanoparticles (ZnONPs) exposure over time. Results The agar-well diffusion assay revealed uniform 9-mm zones of inhibition against all oral pathogens, signifying consistent antimicrobial activity of zinc oxide nanoparticles (ZnONPs). In the time-kill curve assay, Candida albicans exhibited the highest sensitivity, followed by Streptococcus mutans and Staphylococcus aureus. Enterococcus faecalis and Lactobacillus speciesdisplayed lower sensitivity, suggesting potential selectivity. Discussion The observed variation in sensitivity implies the potential selectivity of zinc oxide nanoparticles (ZnONPs) against specific oral pathogens, which may have significant implications for oral health applications. These findings underscore the versatility of green-synthesized zinc oxide nanoparticles (ZnONPs) as promising antimicrobial agents, particularly for oral health applications. Conclusion This study provides promising results for the antimicrobial potential of zinc oxide nanoparticles (ZnONPs) synthesized using Ocimum tenuiflorum and Ocimum gratissimum. The consistent antimicrobial activity and variations in sensitivity among oral pathogens highlight their promising utility in oral health care.

Enhanced production of bacteriocin by Bacillus subtilis ZY05.

Bacteriocin-producing strains were isolated from the soil of the rice field, screened out using an agar-well diffusion assay against six indicator bacterial strains, and the highest among them was selected for further investigation. The study focuses on how different growing conditions affect bacteriocin production. One-parameter-at-a-time (OPAT) and a central composite design of response surface methodology (RSM) were used to perform the optimization in two steps. In the OPAT trials, bacteriocin synthesis was elevated by 29%, 45%, and 34%, by employing sucrose as a carbon source and changing the NaCl concentration and pH at 7, respectively. To determine the linear, squared, and interaction correlations among the process variables to predict the ideal conditions for production, a four-factor central composite design (CCD) of RSM was used. It was determined that the analysis of variance (ANOVA), which produces a recognized model using RSM, is sufficient to describe bacteriocin production regarding activity (R2 = 0.9606). The ideal conditions for increased production were 1.51% sucrose concentration, 1.59% NaCl concentration, pH 6.35, and 28.66 (about 29) hours of incubation. The value predicted by RSM (4051.55 AU/mL) was approximately two times greater than the value of a non-optimized medium. The experimental value of 4403.85 AU/mL was closer to the expected value. According to the data, increasing bacteriocin activity required employing the ideal sucrose concentration, NaCl concentration, and incubation time. The partially purified bacteriocin was found stable at temperatures between 24 and 50°C and at pH 5-8. The molecular weight purified bacteriocin was determined to be between 13 and 35kDa.

Copper Precursor Salt‐Dependent Antimicrobial Activity of Graphite Oxide Composites Against Escherichia coli and Staphylococcus Aureus: Synthesis and Characterization

Graphite oxide (GrO) is doped with Cu(NO3)2 (CuN/GrO) and CuSO4 (CuS/GrO). Face‐centered cubic Cu, monoclinic CuO, and cubic Cu2O mixed crystalline phases are observed. The ID/IG ratio on average is 1.0 for all composites, associated with similar structural disorders and defects. CuN/GrO and CuS/GrO composites increase the C:O ratio by 30% compared to GrO. In Cu(NO3)2‐ and CuSO4‐doped GrO composites, the copper particle dispersion is on the GrO surface and GrO edges, respectively. By agarwell diffusion assay, the CuN/GrO composite presents only inhibition against the Staphylococcus aureus microorganism at 10 mg mL−1 per well. However, using the CuS/GrO composite, the minimum inhibitory concentration is 5 mg mL−1 per well against Escherichia coli and S. aureus microorganisms. In general, the copper precursor salt influences the copper particle localization in the GrO matrix in a different way, modulating the antimicrobial behavior. In this way, it is possible to establish a possible electrostatic adsorption caused by the Cu+ or Cu2+ ions and the negative charges of the bacterial cell membrane, where the adsorption and mass diffusion mechanisms between charged composites and Gram‐positive and Gram‐negative microorganisms are affected by the copper particle arrangement in the composites.

Probiotic Limosilactobacillus reuteri KUB-AC5 decreases urothelial cell invasion and enhances macrophage killing of uropathogenic Escherichia coli in vitro study.

Bacterial urinary tract infections (UTI) are among the most common infectious diseases worldwide. The rise of multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC) UTI cases is a significant threat to healthcare systems. Several probiotic bacteria have been proposed as an alternative to combat MDR UTI. Lactic acid bacteria in the genus Limosilactobacillus are some of the most studied and used probiotics. However, strain-specific effects play a critical role in probiotic properties. L. reuteri KUB-AC5 (AC5), isolated from the chicken gut, confers antimicrobial and immunobiotic effects against some human pathogens. However, the antibacterial and immune modulatory effects of AC5 on UPEC have never been explored. Here, we investigated both the direct and indirect effects of AC5 against UPEC isolates (UTI89, CFT073, and clinical MDR UPEC AT31) in vitro. Using a spot-on lawn, agar-well diffusion, and competitive growth assays, we found that viable AC5 cells and cell-free components of this probiotic significantly reduced the UPEC growth of all strains tested. The human bladder epithelial cell line UM-UC-3 was used to assess the adhesion and pathogen-attachment inhibition properties of AC5 on UPEC. Our data showed that AC5 can attach to UM-UC-3 and decrease UPEC attachment in a dose-dependent manner. Pretreatment of UPEC-infected murine macrophage RAW264.7 cells with viable AC5 (multiplicity of infection, MOI = 1) for 24 hours enhanced macrophage-killing activity and increased proinflammatory (Nos2, Il6, and Tnfa) and anti-inflammatory (Il10) gene expression. These findings indicate the gut-derived AC5 probiotic could be a potential urogenital probiotic against MDR UTI.

Stachys Species: Comparative Evaluation of Phenolic Profile and Antimicrobial and Antioxidant Potential.

This study aimed to investigate the polyphenolic composition and antioxidant and antimicrobial potential of six Romanian Stachys species: S. officinalis, S. germanica, S. byzantina, S. sylvatica, S. palustris, and S. recta. The LC-MS/MS method was used to analyze the polyphenolic profile, while the phenolic contents were spectrophotometrically determined. The antioxidant activity was evaluated using the following methods: DPPH, FRAP, nitrite-induced autooxidation of hemoglobin, inhibition of cytochrome c-catalyzed lipid peroxidation, and electron paramagnetic resonance spectroscopy. The in vitro antimicrobial properties were assessed using agar-well diffusion, broth microdilution, and antibiofilm assays. Fifteen polyphenols were identified using LC-MS and chlorogenic acid was the major component in all the samples (1131.8-6761.4 μg/g). S. germanica, S. palustris, and S. byzantina extracts each displayed an intense antiradical action in relation to high contents of TPC (6.40 mg GAE/mL), flavonoids (3.90 mg RE/mL), and caffeic acid derivatives (0.89 mg CAE/mL). In vitro antimicrobial and antibiofilm properties were exhibited towards Candida albicans, Gram-positive and Gram-negative strains, with the most intense efficacy recorded for S. germanica and S. byzantina when tested against S. aureus. These results highlighted Stachys extracts as rich sources of bioactive compounds with promising antioxidant and antimicrobial efficacies and important perspectives for developing phytopharmaceuticals.

Inhibition of foodborne bacterial pathogens using novel mycosynthesized cobalt nano ferrites and CoFe2O4 nanoparticles anchored on functionalized multi-walled carbon nanotube bionanocomposites

Cobalt nanoferrites and their nanocomposites have attracted significant attention because of their numerous applications. This study reports a novel mycosynthesis of cobalt ferrite nanoparticles (CoFe2O4 NPs) and cobalt ferrite/functionalized multi-walled carbon nanotube (CoFe2O4/fMWCNT) bionanocomposites using the mycelial cell-free filtrate (MCFF) of Aspergillus sojae (KACC 45023). The reaction of A. sojae MCFF with ferric nitrate nonahydrate and cobalt chloride hexahydrate resulted in changing the colorless solution of the MCFF to reddish-brown color and formation of a reddish-brown precipitate, indicating the mycosynthesis of CoFe2O4 NPs. The mycosynthesized CoFe2O4 NPs were biologically anchored onto fMWCNTs using A. sojae MCFF, yielding CoFe2O4/fMWCNT bionanocomposites. Physicochemical and morphological properties of the mycosynthesized CoFe2O4 NPs and CoFe2O4/fMWCNT bionanocomposites were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, zeta potential analysis, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy. The mycosynthesized CoFe2O4 NPs and CoFe2O4/fMWCNT bionanocomposites showed significant antibacterial potential against three foodborne pathogenic bacteria, Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus using an agar-well diffusion assay. The morphological structures of the bacterial cells examined by FESEM revealed changes in the intact bacterial cell structures into misshapen and twisted bacterial cells, as well as deposition of the mycosynthesized CoFe2O4 NPs and CoFe2O4/fMWCNT bionanocomposites on the bacterial cells. The present study reveals the high potential of fungi as valuable bionanofactories for the mycosynthesis of ferrite-based NPs and their bionanocomposites as eco-friendly biosynthesis routes.

The impact of probiotic cell-free metabolites in MDR Pseudomonas aeruginosa: Antibacterial properties and effect on antibiotic resistance genes expression.

There is a significant demand for novel antibacterial agents against multidrug-resistant (MDR) gram-negative bacteria. Recently, probiotics have been noted for their antibacterial properties against various pathogens. This study aimed to investigate the effects of probiotic cell-free supernatants on MDR Pseudomonas aeruginosa. Clinical isolates demonstrating the highest degree of antibiotic resistance were chosen, and the antibacterial effect of probiotic metabolites was evaluated using an agar well diffusion assay. In addition, the effect of probiotics on the expression of resistance genes was evaluated using Real-time PCR. The CFS was assessed using GC-MS to determine the antibacterial compounds. The supernatants inhibited the growth of the isolates (P < 0.0001); however, there was no noticeable difference in the effectiveness of the probiotics. In addition, the supernatants decreased the expression levels of mexD, mexB, mexF, and ampC, and an increase in oprD was observed in some groups. After the assessment of Lactobacillus acidophilus by GC-MS, antibacterial compounds, such as Acetamide, Nonadecane, 9-methyl, and tetradecane, were determined. Our findings showed that probiotic metabolites can effectively inhibit the growth of MDR P. aeruginosa. Gene expression analysis also revealed that the mechanism of antibacterial action was most likely related to the regulation of efflux pumps.

Development of a Pharmaceutical Formulation Containing Clove (Syzygium aromaticum) Extract for the Management of Oral Candidiasis

Introduction: Oral candidiasis is a common fungal infection caused by various yeast species, including Candida albicans, Candida krusei, Candida parapsilosis, Candida tropicalis, and Candida glabrata. Clove, a well-known plant in traditional medicine, has been used as an antiseptic remedy for diverse infections, including those affecting the oral cavity induced by yeasts and bacteria. The emergence of resistance to numerous antifungal agents among Candida species necessitates exploring alternative treatments. Hence, this study aims to evaluate the antimicrobial activities of clove extract and develop a suitable pharmaceutical formulation containing clove extract for managing oral candidiasis. Method: The antimicrobial culture and sensitivity test were conducted using the agar-well diffusion assay, evaluating different concentrations of clove extract against Candida albicans. The minimum effective concentration was then formulated into a gel dosage form, and its antimicrobial activity was assessed, comparing it with miconazole oral gel. Result: The results showed that the prepared clove extract gel had antifungal effects on Candida albicans that were similar to those of the miconazole oral gel. The zone of inhibition for the clove extract gel was measured at 25 mm, while the miconazole gel showed a zone of inhibition of 27 mm. Conclusion: The results of this study show that clove extract gel may be an effective antifungal agent, especially against Candida albicans. This suggests that it may be a promising herbal alternative to conventional medicines for treating oral candidiasis.

Antagonistic activity of lactic acid bacteria isolated from Minas artisanal cheeses against Brucella abortus

This study aimed to evaluate methods for studying the in vitro antimicrobial activity of lactic acid bacteria (LAB) against Brucella abortus and to evaluate the antagonistic effect of LAB on the viability of this pathogen. A total of 18 LAB strains (Lactobacillus plantarum, n = 11; Pediococcus acidilactici, n = 1; Lactobacillus rhamnosus, n = 4; and Lactobacillus brevis, n = 2), isolated from Minas artisanal cheeses produced in three regions (Canastra, Campos das Vertentes, and Araxá) of Minas Gerais State, Brazil, were tested for their antimicrobial activity against B. abortus using three methods: spot-on-lawn, agar well diffusion assay, and antagonistic activity of the culture supernatants. None of the tested LAB strains could inhibit B. abortus in the spot-on-lawn and agar-well diffusion assays. The supernatants produced by LAB had an acidic pH, with intensity depending on bacterial growth and strain, and could inhibit the growth of B. abortus. In contrast, pH-neutralized (pH 7.0) LAB supernatants did not suppress the growth of B. abortus. The results showed that the best technique to study the in vitro antagonism of LAB against B. abortus was the antagonistic activity of culture supernatants. The growth of B. abortus may have been inhibited by acid production.