Agar Diffusion Assay Research Articles

Study on the applicability of potentially probiotic strain Lactobacillus plantarum L4 to be included in the development of strategies for bio-preservation of food products

The antimicrobial activity of potentially probiotic strains is important for their possible application in the development of successful strategies for bio-preservation of different foods. The antimicrobial activity of the potentially probiotic strain Lactobacillus plantarum L4 against the pathogenic bacteria Salmonella abony; Staphylococcus aureus; Escherichia coli and the phytopathogenic fungi Aspergillus niger and Aspergillus flavus was determined using agar-diffusion assay with wells. Lb. plantarum L4 exhibited high antagonistic activity against all test microorganisms included in the study, which was due not only to the production and accumulation of lactic acid and other organic acids, but also to the production of other bioactive substances. The bioactive substances were then submitted to the action of different enzymes. This allowed to observe that they have protein nature, suggesting that they are likely bacteriocins or bacteriocin-like substances. The substances produced by Lb. plantarum L4 did not lose their antimicrobial activity during heat treatment at temperatures above 100 °С for 15 min and they exhibited high inhibitory activity against the test-microorganisms when pH ranged between 4 and 7. After further examination of the properties of the produced antimicrobial compounds, Lb. plantarum L4 can be used in the development of strategies for bio-preservation of different food products.

Floral origin, Antioxidant and Antimicrobial Activity of Some Floral Honey

The study was planned to assess botanic origin, antioxidant power, antimicrobial activity and physicochemical properties of four honey samples were collected in Turkey. The melissopalynologic results revealed that sample 1 and 2 are polyfloral, and others are unifloral. Total content of phenolic (116.47-1711.13 mg GAE/100 g) and flavonoids (1.46 - 27.25 mg CAE/100 g) were analysed, and the antioxidant activities measured by ferrous ion chelating activity (FICA) (71.32-93.35%), hydrogen peroxide scavenging activity (HPSA) (SC50: 217.8-1238.39 µg/mL), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging (SC50: 20.15-27.14 µg/mL), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (SC50: 22.93-308.17 µg/mL) and ferric reducing antioxidant power (FRAP) (71.03-99.54 %) differed notably. For comparison of the samples, butylated hydroxy anisole (BHA), rutin (RUT) and trolox (TRO) were used as standard antioxidant compounds. According to these results, samples showed more efficient antioxidant activity than TRO except for ABTS assay. Also, Sample 1 and 4 have higher FICA activity and Sample 2 and 3 demonstrated more FRAP activity than standards. The minimal inhibitory concentrations (MICs) and agar diffusion assays of honey samples against Staphylococcus aureus and Escherichia coli showed that these samples was the most effective in inhibition of their growth.

Evaluation of a Triple Antibiotic Paste as a Root Canal Obturating Material for Deciduous Teeth: A Study Protocol

Background: Teeth with infected root canals, secondary to endodontic infections are a common problem in primary as well as permanent dentition. The key to successful endodontic treatment is seen only after the complete removal of infection from root canals. Systemic antibiotics have limited reach to endodontic spaces. In pediatric dentistry, difficulties in antimicrobial control require the development of a new root canal obturating paste with broad antimicrobial activity, minimal tissue toxicity, and high safety index. In this experimental study, a new Triple Antibiotic Obturating Paste (TAOP) will be developed and its efficacy will be evaluated.
 Methods and Design: This is a pre-clinical in-vitro microbiological and in-vivo animal study, utilizing laboratory-grown white Wistar rats aged 2-3 months and weighing 200-300 grams. The antibiotic sensitivity test (AST) will be conducted using 21 standard aerobic and anaerobic microbial strains for determining potency through serial dilution and agar diffusion assay. The systemic and local tissue toxicity will be assessed by inserting the test and control materials into the dorsal connective tissues of the experimental rats. The antimicrobial efficacy of triple antibiotic obturating paste [thermo-modulated in-situ polymeric hydrogel matrix of TAOP, containing chitosan-carbopol and poloxamer blended with clindamycin (5%), metronidazole (5%), and doxycycline (1%)] will be evaluated against Metapex [Ca(OH)2-Iodoform paste] on endodontic microflora. The microbiological study data will be evaluated through One-way ANOVA trailed by ‘Tuckey’s post hoc test’ for intergroup as well as, t-test for intragroup comparison. The animal study data will be evaluated through One-way ANOVA for intergroup and ‘paired t-test’ for intragroup comparison.
 Results: The newly developed bio-degradable obturating material will be more suitable than the conventionally used one, to eliminate resistant endodontic pathogens from root canal systems, along with good pharmacokinetic and pharmacodynamic responses as well as minimal local and systematic tissue toxicity when used in primary teeth.
 Conclusion: The application of such novel multi-antibiotic formulation as an obturating material not only will achieve efficient disinfection of the endodontic spaces but also increase chances of therapeutic success due to the elimination of side effects associated with cytotoxicity and material properties as it contains most of the bioresorbable organic ingredients.

Determination of an Expedient Method for Screening Quorum Quenching (QQ) Rhizobacteria with Choromobacterium violaceum (CV) RU9 as Bioindicator

Quorum quenching (QQ) is the process of hindering the auto-inducer molecules that acts as quorum sensing (QS) signals. Quorum sensing signals, the Acyl homoserine lactones play a major role in induction of virulence in Pectobacterium carotovorum subsp. carotovorum (Pcc), the most acclaimed causative agent of soft rot disease in several vegetable crops. The disease sounds so alarming because it is also an infamous post-harvest affliction. Disruption of the QS signals will halt the production of QS induced secretion of the plant cell wall degrading virulence enzymes. Thus, in the present study it was attempted to screen rhizobacterial isolates for their ability to produce degradative enzymes for the disruption of the QS signal molecules. Three methods, soft agar diffusion assay, soft agar overlay assay and disc diffusion assay were trailed out with a basic modification to choose the most befitting method. For the assay we used Choromobacterium violaceum (CV) strain RU9 as a bioindicator rather than the mutant strain CV026. Of the three methods of screening, the soft agar overlay assay was chosen as the pre-eminent method for screening which further required standardization of cell load of CV cells for the overlay. 1% to 5% CV RU9 cells were overlaid and their violacein units were determined simultaneously. A concentration of 3% CV RU9 cells had 812 violacein units for overlay was determined to be the appropriate concentration. Soft agar overlay assay with 3% CV RU9 cells was used to determine the quorum quenching ability of the rhizobacterial strains isolated from various crops.

Biological Investigation of Amaryllidaceae Alkaloid Extracts from the Bulbs of Pancratium trianthum Collected in the Senegalese Flora.

Amaryllidaceae plants are rich in alkaloids with biological properties. Pancratium trianthum is an Amaryllidaceae species widely used in African folk medicine to treat several diseases such as central nervous system disorders, tumors, and microbial infections, and it is used to heal wounds. The current investigation explored the biological properties of alkaloid extracts from bulbs of P. trianthum collected in the Senegalese flora. Alkaloid extracts were analyzed and identified by chromatography and mass spectrometry. Alkaloid extracts from P. trianthum displayed pleiotropic biological properties. Cytotoxic activity of the extracts was determined on hepatocarcinoma Huh7 cells and on acute monocytic leukemia THP-1 cells, while agar diffusion and microdilution assays were used to evaluate antibacterial activity. Antiviral activity was measured by infection of extract-treated cells with dengue virus (DENVGFP) and human immunodeficiency virus-1 (HIV-1GFP) reporter vectors. Cytotoxicity and viral inhibition were the most striking of P. trianthum’s extract activities. Importantly, non-cytotoxic concentrations were highly effective in completely preventing DENVGFP replication and in reducing pseudotyped HIV-1GFP infection levels. Our results show that P. trianthum is a rich source of molecules for the potential discovery of new treatments against various diseases. Herein, we provide scientific evidence to rationalize the traditional uses of P. trianthum for wound treatment as an anti-dermatosis and antiseptic agent.

Microbiological Antibiotic Assay Validation of Gentamicin Sulfate Using Two-Dose Parallel Line Model (PLM)

Till nowadays microbiological assay is still widely used with several antibiotics that are composed of a mixture of related active compounds. However, obtaining a reasonably valid determination of the potency is dependent on the validity and the suitability of the assay design. The present work aimed to validate an assay design of an aminoglycoside antibiotic (Gentamicin Sulfate) using a two-dose Parallel Line Model agar diffusion assay in a large 8×8 rectangular plate. All preparatory procedures were done following United States Pharmacopeia and the Inhibition Zones were measured using a digital caliper to the nearest 0.01 mm. Analysis of variance of compendial requirements of regression and parallelism were found to be satisfactorily meeting the acceptance criteria. Specificity was achieved for the product under investigation with no detectable IZ that could be found for all components except the antibiotic. The validation method showed acceptable linearity of r2≥0.98. Accuracy and precision parameters showed RSD (%)<2. All relative error value estimates were below 4%. The proposed validation design for 32×32 cm antibiotic plates yielded valid results and can be projected for the routine Quality Control analysis of the antibiotic material, especially which is incorporated into a finished medicinal dosage form. Doi: 10.28991/HIJ-2021-02-04-04 Full Text: PDF

Antifungal activity and chemical composition of neem seed extract (Azadirachta indica A.)

The antifungal activities and chemical composition of neem seed extract (Azadirachta indica) were investigated. An agar diffusion assay showed that neem seed extract (optimum concentration: 10%) inhibited the growth of Trametes versicolor and Gloeophyllum trabeum. The minimum inhibitory concentration and minimum fungicidal concentration were 2% and 4%, respectively, against the two fungal species. Scanning electron microscopy revealed severe morphological damage to fungal hyphae, including reduction of spores and hyphal shriveling. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry analyses identified 17 compounds that represented 80.3% of the total extract, including astaxanthin (34.3%), cinobufagin (16.9%), anodendro-side A (6.65%), 16-acetoxy-4,8,14-trimethyl-3,11-dioxo-, methyl ester (5.09%). Furthermore, T. versicolor-infected wood and G. trabeum-infected wood treated with 10% neem seed extract displayed mass decreases of 11.4 ± 5.8% and 25.8 ± 7.5%, respectively, compared with distilled water treatment (21.6 ± 4.2% and 46.9 ± 4.3%, respectively). These findings suggest the potential use of neem seed extract for antifungal wood protection.

Eco-friendly synthesis of zinc oxide nanoparticles using Rivina humilis leaf extract and their biomedical applications

In this study, we synthesized zinc oxide nanoparticles (ZnONPs) using aqueous leaf extract from Rivina humilis and its functions such as antioxidant, antibacterial and anticancer activities were investigated. ZnONPs were further characterized by UV–vis spectrophotometric analysis (UV–vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Transmission electron microscope and Energy dispersive X-ray spectroscopy (EDX). The synthesized ZnONPs exhibited a strong SPR peak at 370 nm. The XRD results confirming that the ZnONPs were crystalline in nature. Electron microscopic data depicted that these nanoparticles were irregular and circular in appearance with a size of 14.4 nm. The ZnONPs exhibited remarkable antioxidant activities than the extract of R. humilis. The antibacterial effect of ZnONPs against bacterial species was determined by agar diffusion assay. Further, Neuro 2a neuroblastoma cells indicated a dose-dependent decrease of viable cells when exposed to ZnONPs (5–100 μg/ml). ZnONPs induces a huge amount of lipid peroxidation end product malondialdehyde thus driving the cancer cells to be apoptosis. Moreover, treatment of Neuro 2a cells with ZnONPs brings about activation of apoptotic cell death through the intrinsic mitochondrial pathway by overexpressing caspases 3 and 9 while the reduction in Bcl-2 and upregulation of Bax protein.

Comparative antimicrobial efficacy study of different commercially available toothpaste in India: An in vitro study

Antimicrobial chemotherapeutic agents have been recommended for lowering oral bacteria growth. The main purpose of this study is to examine the efficacy of different toothpaste formulations in providing complete oral cavity protection against oral pathogens. By using a modified well agar diffusion assay, twenty kinds of toothpaste were examined for antimicrobial efficacy against two oral pathogens: Streptococcus aureus and Escherichia coli. The examination indicated that the majority of the non-herbal dentifrices and combinations of herbal and chemical-based dentifrices chosen for the investigation were viable against both microbial strains, however, to differing degrees. TP1 and TP17 were found the best against E. coli and S. aureus, respectively, with 21.553 mm and 23.443 mm as the zone of inhibition. From the herbal dentifrices, TP15 was found to have significant effect on E. coli, followed by TP19 for S. aureus. Nevertheless, toothpaste TP15 and TP19 were not effective against S. aureus and E. coli, respectively. In correlation, the inhibition zones of every single other dentifrice were found to be less. Antimicrobial activity against test organisms was stronger in a sodium lauryl sulphate-based dental formulations, when combined with fluoride. A formulation including TP15 exhibited substantial activity against the tested bacterium E. coli among herbal dentifrices. Statistical analysis demonstrated that the effectiveness against Gram-negative bacteria was greater than against Gram-positive bacteria. Furthermore, herbal toothpaste can be incorporated with chemotherapeutic agents to enhance its effectiveness against pathogens present in the oral microbiome. This comparison aids in the identification of the toothpaste’s shortcomings and benefits over other formulations, widening the scope of more potent toothpaste products.

Development of an agar-plug cultivation system for bioactivity assays of actinomycete strain collections.

Natural products are an important source of lead compounds for the development of drug substances. Actinomycetes have been valuable especially for the discovery of antibiotics. Increasing occurrence of antibiotic resistance among bacterial pathogens has revived the interest in actinomycete natural product research. Actinobacteria produce a different set of natural products when cultivated on solid growth media compared with submersed culture. Bioactivity assays involving solid media (e.g. agar-plug assays) require manual manipulation of the strains and agar plugs. This is less convenient for the screening of larger strain collections of several hundred or thousand strains. Thus, the aim of this study was to develop a 96-well microplate-based system suitable for the screening of actinomycete strain collections in agar-plug assays. We developed a medium-throughput cultivation and agar-plug assay workflow that allows the convenient inoculation of solid agar plugs with actinomycete spore suspensions from a strain collection, and the transfer of the agar plugs to petri dishes to conduct agar-plug bioactivity assays. The development steps as well as the challenges that were overcome during the development (e.g. system sterility, handling of the agar plugs) are described. We present the results from one exemplary screening campaign targeted to identify compounds inhibiting Agr-based quorum sensing where the workflow was used successfully. We present a novel and convenient workflow to combine agar diffusion assays with microtiter-plate-based cultivation systems in which strains can grow on a solid surface. This workflow facilitates and speeds up the initial medium throughput screening of natural product-producing actinomycete strain collections against monitor strains in agar-plug assays.

Antibacterial, antioxidant and neuroprotective activities of crude extract from the endophytic fungus Fusarium sp. isolate OQ-Fus-2-F from Euphorbia sp. plant

Context: Human life is contested with the emergence of new infectious diseases and antibiotic-resistant pathogens, cellular deterioration due to oxidative stress, and age-related neurodegenerative disorders. Aims: To evaluate the antibacterial, antioxidant, and acetylcholinesterase inhibitory activities of crude extract from the endophytic fungus Fusarium sp. isolate OQ-Fus-2-F as a basis for medical application. Methods: Fusarium sp. isolate OQ-Fus-2-F was isolated from the stem of Euphorbia sp. plant. It was identified morphologically and based on 18S rRNA gene partial sequence. The isolated was cultivated in a malt extract glucose medium. Cell filtrate was extracted with ethyl acetate, and the crude extract was dried in vacuum. The crude extract was assessed for its antimicrobial activity through agar diffusion and micro-broth dilution assays; antioxidant activity was measured using DPPH and ABTS methods, and the anticholinergic activity was evaluated in terms of inhibition in acetylcholinesterase (AChE) activity. Results: Crude extract of Fusarium sp. isolate OQ-Fus-2-F was more potent in inhibiting the growth of B. subtilis with a MIC value of 125 µg/mL. Its antioxidant activity was highly detected in ABTS than DPPH assay with IC50 values 37.5 ± 3.5 µg/mL and 191.3 ± 17.6 µg/mL, respectively. Moreover, the extract inhibited the AChE activity with IC50 177.0 ± 13.7 µg/mL. Conclusions: Crude extract of Fusarium sp. isolate OQ-Fus-2-F has potential biomedical applications as it contains secondary metabolites with antimicrobial, antioxidant, and neuroprotective activates.

Isolation and Structure Elucidation of Desferrioxamine B and the New Desferrioxamine B2 Antibiotics from a Brown Marine Macroalga Carpodesmia tamariscifolia Associated Streptomyces Isolate

Today, emerging infectious diseases caused by multidrug-resistant bacteria (MDRB) are a major public health problem. These bacteria are gradually becoming more resistant to conventional antimicrobial agents. Thus, there is an urgent requirement to explore new antimicrobial compounds. This study focuses on a screening program of marine actinobacteria for useful bioactive compounds against MDRB, and four endophytic actinobacteria strain isolated from the unexploited marine brown alga Carpodesmia tamariscifolia, harvested from the Atlantic coast of Morocco, were screened for their antimicrobial activities using the agar diffusion assay. Fermentation broths of the two selected promising isolates KC179 and KC180 were extracted with different organic solvents and showed antibacterial activity against methicillin-resistant Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa. From the butanolic extract of KC180's culture broth and in addition to the known metabolite desferrioxamine B, a new desferrioxamine derivative, desferrioxamine B2, was purified using flash chromatography and reversed-phase HPLC, and its structure was elucidated using HRMS and NMR spectroscopy. The 16S rRNA molecular taxonomic characterization of the producing strain KC180 showed Streptomyces albidoflavus as the nearest relative, with a sequence similarity of 99.71 %.

In Vitro Antibacterial Activity of Myrtus communis L. and Marrubium vulgare L. Leaves against Aggregatibacter actinomycetemcomitans and Eikenella corrodens.

Materials and Methods Clinical strains of Aggregatibacter actinomycetemcomitans and Eikenella corrodens and two reference strains of A. actinomycetemcomitans were tested. The antibacterial activity of each studied plant extract was evaluated using agar diffusion and broth microdilution assays. Results Both aqueous and methanolic extracts of M. communis exhibited high antibacterial activity against periodontal pathogens as compared to M. vulgare extracts. At concentrations of 2.5-0.32 mg/disc, inhibition zones of the methanolic extract of M. communis ranged from 19.66 ± 0.57 to 12.33 ± 0.57 mm. The methanolic extract of M. vulgare showed at concentrations of 5-0.63 mg/disc inhibition zones ranging from 15.66 ± 0.57 to 12 ± 0.00 mm. Its aqueous extract at concentration of 0.63 mg/disc showed no antimicrobial activity against the clinical and reference strain of A. actinomycetemcomitans. Conclusion. This study showed that methanolic and aqueous extracts of M. communis and M. vulgare have in vitro an antibacterial activity against periodontal pathogens. They could be use as ingredients of an oral antimicrobial agent for prevention or treatment of periodontal diseases. Further research on isolating the compounds from these plant extracts and their toxicity effect could be conducted.

OxyR inactivation reduces the growth rate and oxidative stress defense in Capnocytophaga ochracea

ObjectiveThe human oral cavity harbors several bacteria. Among them, Capnocytophaga ochracea, a facultative anaerobe, is responsible for the early phase of dental plaque formation. In this phase, the tooth surface or tissue is exposed to various oxidative stresses. For colonization in the dental plaque phase, a response by hydrogen peroxide (H2O2)-sensing transcriptional regulators, such as OxyR, may be necessary. However, to date, no study has elucidated the role of OxyR protein in C. ochracea. MethodsInsertional mutagenesis was used to create an oxyR mutant, and gene expression was evaluated by reverse transcription-polymerase chain reaction and quantitative real-time reverse transcription-polymerase chain reaction. Bacterial growth curves were generated by turbidity measurement, and the sensitivity of the oxyR mutant to H2O2 was assessed using the disc diffusion assay. Finally, a two-compartment system was used to assess biofilm formation. ResultsThe oxyR mutant grew slower than the wild-type under anaerobic conditions. The agar diffusion assay revealed that the oxyR mutant had increased sensitivity to H2O2. The transcript levels of oxidative stress defense genes, sod, ahpC, and trx, were lower in the oxyR mutant than in the wild-type strain. The turbidity of C. ochracea, simultaneously co-cultured with Streptococcus gordonii, was lower than that observed under conditions of homotypic growth. Moreover, the percentage decrease in growth of the oxyR mutant was significantly higher than that of the wild-type. ConclusionsThese results show that OxyR in C. ochracea regulates adequate in vitro growth and escapes oxidative stress.

Antimicrobial and antibiofilm effects of total flavonoids from Potentilla kleiniana Wight et Arn on Pseudomonas aeruginosa and its potential application to stainless steel surfaces

Pseudomonas aeruginosa (P. aeruginosa) contamination poses challenges to the food industry. Total flavonoids of Potentilla Kleiniana Wight et Arn (TFP) are poorly understood for their antibiofilm effects against P. aeruginosa. Therefore, the inhibitory effects of TFP against planktonic cells were determined by agar diffusion, microtiter plate and time-kill curve assays. The mechanism of inhibition is evaluated by changes in membrane (potential, permeability and damage), cell motility and virulence factors production. Morphological changes were verified by transmission electron microscopy (TEM). A modified microtiter-plate assay determined its inhibitory effects against biofilm cells. The inhibitory mechanism was studied by changes in extracellular polymeric substances (EPS) and cell surface hydrophobicity. These inhibition effects were verified by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Finally, TFP was applied to stainless steel surfaces to evaluate its potential application in food production. TFP damaged P. aeruginosa cell membrane integrity, inhibited bacterial motility, virulence factors, surface hydrophobicity and colony counting on stainless steel. These results provide evidence for the utilization of TFP as a novel natural bioactive preservative in food processing.

Screening of Lactic Acid Bacteria with Anti- Helicobacter pylori Activity and Evaluation of Their Probiotic Characteristics

Objective: To screen lactic acid bacteria (LAB) with anti-Helicobacter pylori activity and great probiotic properties from fermented food, dairy products and infant feces. Method: A total of 39 LAB-like strains with stable curd state were screened from 175 samples. 9 Strains with anti-H. pylori activity were initially isolated by agar diffusion assay and H. pylori urease activity test and identified by 16S rDNA sequence analysis. Subsequently, the acid and bile tolerance, antibiotic resistance, antibacterial activity, cell surface hydrophobicity, and cell auto-aggregation of the selected LAB strains were determined. Results: Two probiotic strains with anti-Helicobacter pylori activity were screened: Lactobacillus helveticus GQ1702 and Lactobacillus plantarum D1, and their cell culture supernatants exhibited anti-H. pylori activity equivalent to the anti-H. pylori activity of 0.038 and 0.034 mg/mL metronidazole, respectively. The survival rates of GQ1702 and D1 were above 70% after incubation at pH3 for 3 h, the survival rates of GQ1702 and D1 after incubation at 0.3% bile salt were 0.47% and 1.08%, respectively. Cell surface hydrophobicities of GQ1702 and D1 were 25.10% and 11.79%, respectively. The self-agglutination rate reached 71.18% and 50.78% respectively after 24 hours. The auto-aggregation percentages of GQ1702 and D1 were 61.18% and 57.25%, respectively, after 24 hours. The two LAB strains were not resistant to chloramphenicol, penicillin, erythromycin, ampicillin, or cefazolin, and exhibited antimicrobial activity against Staphylococcus aureus, Listeria monocytogenes, E. coli O157:H7, and Salmonella typhimurium. Conclusion: Lactobacillus helveticus GQ1702 and Lactobacillus plantarum D1 with anti-Helicobacter pylori activity were obtained in this experiment, which could provide a source of strains for development and research of functional dairy products.

Ionic liquid based antimicrobial coating on polymeric surface: A green chemistry approach

A sustainable and green method to impart antimicrobial properties to materials or devices made of Poly (propylene) (PP) is of great interest to many in academia and the industry. Herein, we demonstrate a simple strategy to impart antimicrobial property to PP filter materials by interfacial self-assembly of an ionic liquid (IL), 1-hexyl-3-methylimidazolium iodide (HMIMI). HMIMI was found to have a minimum inhibitory concentration (MIC) of 8.5 mM against Escherichia coli (E. coli) and a critical micelle concentration (CMC) of 465 mM. Self-assembly of HMIMI over PP was found to prevent the adhesion of E. coli, which was illustrated by Agar diffusion assay, Confocal Raman Microscopy, and Scanning Electron Microscopy. The green strategy employed here would be helpful to generate cost-effective antimicrobial surfaces for various biomedical applications.

Development of eco-friendly antifungal coatings by curing natural seed oils on wood

Protective green coatings are advantageous because they are eco-friendly and sustainable. In this study, three natural seed oils, tung, linseed and soybean, were used to investigate how coatings with different oil compositions could inhibit fungal growth. The oils were placed under direct sunlight to form cured films on maple wood. The curing chemistry and its effect on chemical resistance, water resistance and thermal stability were characterized and evaluated by FTIR, 13C NMR, solvent immersion, water contact angle and thermogravimetric analysis. The oil-coated samples were then placed on agar petri dishes that were spread with white-rot fungi. The areas of growth inhibition were measured over several days using an agar diffusion assay. The results showed that all oil-based coatings inhibited the fungal growth, with tung oil being the most effective followed by linseed and soybean oils. By mixing with a small fraction of tung oil, both linseed and soybean oils showed curing rates at least two times faster than individual oils and demonstrated much better inhibition of growth against fungi. This class of green natural seed oil coatings could be beneficial both economically and socially, given their high abundance, low cost, and environmental friendliness.

The Efficacy of Silver-Based Electrospun Antimicrobial Dressing in Accelerating the Regeneration of Partial Thickness Burn Wounds Using a Porcine Model.

(1) Background: Wounds with damages to the subcutaneous are difficult to regenerate because of the tissue damages and complications such as bacterial infection. (2) Methods: In this study, we created burn wounds on pigs and investigated the efficacy of three biomaterials: polycaprolactone-gelatin-silver membrane (PCLGelAg) and two commercial burn dressings, Aquacel® Ag and UrgoTulTM silver sulfadiazine. In vitro long-term antibacterial property and in vivo wound healing performance were investigated. Agar diffusion assays were employed to evaluate bacterial inhibition at different time intervals. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assays were used to compare antibacterial strength among samples. Second-degree burn wounds in the pig model were designed to evaluate the efficiency of all dressings in supporting the wound healing process. (3) Results: The results showed that PCLGelAg membrane was the most effective in killing both Gram-positive and Gram-negative bacteria bacteria with the lowest MBC value. All three dressings (PCLGelAg, Aquacel, and UrgoTul) exhibited bactericidal effect during the first 24 h, supported wound healing as well as prevented infection and inflammation. (4) Conclusions: The results suggest that the PCLGelAg membrane is a practical solution for the treatment of severe burn injury and other infection-related skin complications.

Antioxidant and antimicrobial activities of exopolysaccharides produced by a novel Aspergillus sp. DHE6 under optimized submerged fermentation conditions

Microbial exopolysaccharides are biomacromolecules that are known for their significant importance. Fungal exopolysaccharides are widely utilized in different biotechnological applications such as pharmaceuticals, medicine, cosmetics and food. In this study, fifty fungal isolates were screened for their exopolysaccharides production under submerged fermentation. A novel Aspergillus sp. DHE6 was found to be the best exopolysaccharides producer, with a yield of 7.2 ± 0.24 g/L. Optimization of culture conditions increased exopolysaccharides yield by 3.6-fold (26.1 ± 0.42 g/L). The optimal incubation temperature, initial medium pH, incubation period and the rate of agitation were 30 °C, 6.0, ten days and 150 rpm, respectively. The best carbon and nitrogen sources were glucose at 40 g/L and yeast extract at 1.5 g/L, respectively. Exopolysaccharides were partially purified from Aspergillus sp. DHE6 and characterized using FT-IR-spectrum. Major functional groups were –OH, –CH, –C C, and C– O –C. The partially purified Aspergillus sp. DHE6 exopolysaccharides exhibited excellent antioxidant activity with median effective concentration (EC 50 ) of 573.6 μg/mL using DPPH radical scavenging assay. Agar diffusion assay showed that exopolysaccharide exhibited strong antibacterial activity against the tested hazardous human pathogens ( Staphylococcus aureus , Bacillus subti lis, Bordetella pertussis and Pseudomonas aeruginosa ). Therefore, these results suggest the suitabilility of Aspergillus sp. DHE6 exopolysaccharides for medical purposes and food industry. • Hyper production of exopolysaccharides from a novel terrestrial fungus Aspergillus sp. DHE6. • Optimization of culture conditions increased exopolysaccharides yield by 3.6-fold. • Exopolysaccharides were partially purified and characterized using FTIR-spectrum. • The major functional groups were –OH, –CH, –C C, and C– O –C. • Exopolysaccharides exhibited excellent antioxidant and antibacterial activities.