جستجوی مقالات مرتبط با کلیدواژه « ضدباکتریایی » در نشریات گروه « زیست شناسی »

Although there are different methods for the production of nanoparticles, today the synthesis of nanoparticles with biological methods has attracted the attention of researchers because it is an easy, environmentally friendly, and cost-effective method. The present study investigates the biosynthesis of gold nanoparticles using Lactobacillus paracasei (MN809528) exopolysaccharide and studies the antibacterial, anti-biofilm, and antioxidant properties.

For the synthesis of gold nanoparticles, 30 ml of 1% exopolysaccharide (0.1 g) solution was added to an equal volume of 1 mM aqueous HAuCl4 solution and mixed well using stirred (180 rpm) for 48 h at room temperature. The characterization of synthesized gold nanoparticles was performed using UV-VIS, FT-IR, DLS, XRD, EDX, FE-SEM spectroscopic analysis. Antibacterial activity of produced gold nanoparticles by agar well diffusion method, anti-biofilm activity by 96 well microplate dilution method, and antioxidant activity of nanoparticles using DPPH radical adsorption capability were examined.

Spectroscopic data showed the presence of a peak at 524 nm, which is specific to gold nanoparticles. Examination of the shape and size of nanoparticles with FE-SEM showed that the produced nanoparticles were spherical in shape and their average size is 2o-50 nm. Antibacterial activity of gold nanoparticles at a concentration of 50 µg /ml was observed against all bacterial tests. However, the highest antibacterial activity was observed against Acinetobacter baumannii (ATCC 17978). In the present study, the gold nanoparticles produced acted as biofilm and DPPH radical inhibitors.

The results of the study show that Lactobacillus paracasei (MN809528) is a good biological source for the synthesis of gold nanoparticles. The study is the first report on the production of gold nanoparticles by exopolysaccharides isolated from indigenous lactic acid bacteria.

Inocutis levis is a polypore basidiomycete from the Hymenochaetaceae family. Members of this family have well-known medicinal properties. Recently, anti-diabetic and anti-hypercholesterolemic effects of I. levis have been reported. This study aimed to evaluate antibacterial activities and antioxidant properties of the extracts of I. levis.

After the sampling and fungus identification, the methanolic, ethanolic, and aqueous extracts of the dried fruiting bodies of I. levis were prepared. The antioxidant activities were determined by DPPH method, and antibacterial activities by microdilution method against some gram-positive and gram-negative bacteria. Furthermore, the identification and quantification of phenolic and flavonoid compounds of the extracts were investigated by spectrophotometers and HPLC.

The results showed that the methanolic extract had the highest DPPH scavenging activity, with an IC50 value of 555 µg/ml. The ethanolic and methanolic extracts showed the same antibacterial effects, and Streptococcus mutansATCC35665 was more sensitive than other bacteria, with the MIC and MBC values of 12.5 and 25 mg/ml, respectively. Total phenolic (34.15mg gallic acid) and total flavonoid contents (5.4mg quercetin) per 1 gram dry methanolic extract were higher than other extracts. Furthermore, in the HPLC analysis, ascorbic acid, resorcinol, caffeic acid, catechin and, vanillic acid were determined.

This is the first study presenting the antibacterial and antioxidant properties of I. levis. The results can be considered for future studies in the design of new antibiotics and antioxidant compounds from natural resources applying native fungi.

Industrial usage of different macroalgae has grown exponentially during the last decade. Nutritional applications for human feeding and multiple therapeutic are their main important exploitation. This study aimed to investigate the biological activities of the organic, water and ethyl acetate fractions of two brown algae Polycladia myrica and Padina sp., collected from the coast of Qeshm Island. In this experimental study, for identification of the superior species, the tested biological activities included antioxidant assay at gradient concentrations by ferric reducing power assay, FRAP, inhibition free radicals DPPH and ABTS, total phenolic and phlorotannins content, and antibacterial assay by disk diffusion. The more effective algal fractions by maximum antioxidant capacity in all tested methods were recorded for ethyl acetate fractions in both macroalgae. Only ethyl acetate fraction of Padina sp. had an antibacterial effect on all studied strains. Both brown algae, Polycladia myrica and Padina sp., had antioxidant and antibacterial activities, but Padina sp. due to the high amount of phenol and phlorotannins and high antioxidant and antibacterial power can be introduced as a priority species for biological properties.

Nowadays, researchers need to produce eco-friendly nanoparticles through synthetic methods without using toxic and hazardous chemicals. Environmental pollutions, such as chemical and physical contaminants can be produced by various chemical and physical processes during nanoparticle production. Therefore, researchers have made many efforts to synthesize eco-friendly Nano-materials using enzymes, microorganisms, and plant extracts. In recent years, along with using genetic engineering for producing GM plants tolerant to pests, due to their low environmental risks and biosafety issues, synthesizing of Nano-metals using plant extracts has been considered by researchers. Plant extracts contain reducing agents that can reduce the metal salts to their ions. Moreover, the synthesis of nanoparticles using plant extracts could be considered as a simple, cost effective, and environmentally friendly approach. In the present review paper, we discuss various green and eco-friendly methods using different plant extracts to produce silver, gold, copper, and iron nanoparticles as antibacterial materials.

Streptococcosis is the most destructive disease in world aquaculture, and many efforts have been made to curb this bacteria. In this study, the ability of artificial polypeptide hepcidin (EC-hepcidin1) was evaluated to control infection caused by Streptococcus iniae in primary cell culture of rainbow trout (Oncorhynchus mykiss). Antibacterial effects of this polypeptide were examined by disk diffusion and minimum inhibitory concentration (MIC) and minimum bactericidal concentration of EC-hepcidin1 were measured against Streptococcus iniae. The primary cells were produced from fish fin, and the toxicity range of the peptide was determined for the cells. The primary cells of the rainbow trout were infected with Streptococcus iniae and antimicrobial activity of EC-hepcidin1, as well as viability of the cells, were evaluated. Results showed the MIC and MBC were 75 and 150 μg/mL, respectively. The level of peptide toxicity on fish cells show that EC-hepcidin1 had low toxicity after 48h in the range of 25 to 400 μg/mL, and the cells had a viability of 60% to 80%. The viability of the cells was 55% after induction of the bacteria (10: MOI), and the survival rate of cells was increased up to 90% after induction of bacteria (10: MOI) with 150 μg/mL peptide. In conclusion, the EC-hepcidin1 has shown an antibacterial effect on Streptococcus iniae (in vitro) and the peptide has low toxicity to fish cells. It has increased the vitality of cells infected with Streptococcus iniae. Therefore, complementary clinical research on larval stage, as well as broodstock of rainbow trout, could be suggested in the future. In conclusion, the EC-hepcidin1 has been shown an antibacterial effect on Streptococcus and low toxicity to fish cells. It has increased the vitality of cells infected with Streptococcus. Therefore, complementary clinical research on larval stage and broodstock of fish could be suggested.

Recently, polymer-based nanofibrous scaffolds have attracted great attention due to their significant antibacterial properties in the field of dermatological applications. In this study, a polycaprolactone-based nanofibrous scaffold has been fabricated using the electrospinning method. The aim of this study was to evaluate the antibacterial effect of electrospun nanofibrous structures.

In this experimental study, the structure and bacterial attachment on polymeric nanofibrous scaffolds were studied by Scanning Electron Microscopy (SEM). In addition, antibacterial properties of nanofibrous scaffolds were studied on two gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa and two gram-positive bacteria of Staphylococcus aureus and Streptococcus mutans, using microdilution method and biofilm assay. Moreover, MTT assay was performed on HeLa and human fibrosarcoma cell line (HT1080) cancerous cell lines to evaluate the cell viability.

The results of this study showed that nanofibrous scaffold revealed a significant antimicrobial and anti-biofilm formation effect on all of the studied bacterial strains, but in microscopic observations and microdilution assay was observed on Pseudomonas aeruginosa in 1mg/ml of nanofibrous scaffold extract concentration, while the major effect in biofilm assay was observed in 8µg/ml of extract concentration. Moreover, the cell viability studies showed that the most significant effect was shown on HT1080 cell line which has drastically decreased by 40% after 48 hours in comparison with the control.

These results show that electrospun nanofibrous PCL-based scaffolds are potentially promising for dermal tissue engineering applications, due to anti-biofilm effects and capability of reducing the number of cancerous cells in the wound site.

Considering the importance of health and some disadvantages of the existing synthetic compounds, the present research aimed at evaluating the antibacterial and antioxidant potential of Haliclona caerulea extracts. In the present experimental study, organic extracts of n-hexane, diethyl ether, and methanol were prepared by the Bligh and Dyer method from the marine sponge; then, antibacterial activity was measured by disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC), and antioxidant activity was measured by evaluating the regenerative power and determining the total antioxidant capacity of the extracts. The data were analyzed by Duncan's new multiple range test (MRT) one-way ANOVA test. SPSS 19 and Excel 2013 software were used. Findings: Methanol extract had the most antibacterial effect, especially against Gram positive bacterial of Bacillus subtilis with a concentration of 2.5mg/ml and Staphylococcus aureus with a concentration of 5mg/ml. Diethyl ether extracts showed the highest antioxidant activity at concentration of 5mg/ml. The methanol extract of Haliclona caerulea exhibits more antibacterial properties, and the diethyl ether extract of this sponge have a higher antioxidant effect.

Enhancing the survival of the aquatic products is one of the most important concerns during processing industry. So the aim of present study was evaluating the antibacterial effects of rosemary essence and nisin on silver carp’s fillet. The treatments had composed of rosemary (1.5%), nisin (0.5g/Kg), both nisin and rosemary and control group without any additive. In order to evaluate the antibacterial efficiency of rosemary and nisin, the Salmonella typhimurium (as an index pathogenic bacteria, 5 log CFU/g) was inoculated on silver carp’s fillet and the growth of the bacteria was measured every three days (0, 3, 6, 9). The results revealed that the significant positive effect has been observed in all treatments in comparison with the control group (P

Due to the ability of algae in production of secondary metabolites, they can be a potential source of natural compounds used for drug development and treatment of many diseases. Therefore, present study has been performed to determine the antioxidant and antibacterial activity of aqueous extract of brown algae Iyengaria stellata from the coast of Qeshm, Iran. The evaluation of antioxidant activity of algae extract, investigated by measuring the inhibitory effect of hydroxyl radicals, chelating ability of ferrous ions and total antioxidant activity. Antibacterial activity of extract against four strains of pathogenic bacteria, including Escherichia coli, Salmonella typhimurium, Bacillus cereus and Staphylococcus aureus, was evaluated by disc diffusion method and the results were compared with standard antibiotics. The total antioxidant activity, hydroxyl radical scavenging ability and the ability of ferrous ions chelating were high in algae. But the results of antimicrobial tests showed that the aqueous extract of Iyengaria stellata had no antibacterial effect on studied bacteria. According to the results, brown algae Iyengaria stellata can be used as a potential source of antioxidant compounds in food and pharmaceutical industries.

Marine algae are shown to contain a wide range of bioactive compounds, which have commercial application in pharmaceutical, medical, cosmetic, nutraceutical, food and agricultural industries. The biological activity of the natural bio-active compounds in algae has wide effects on bacteria, tumors and antioxidant activities. The purpose of this study was to determine antibacterial activity of the marine algae. Different algae (green, brown, red) were subjected to the three solvents (n-hexan, ethyl acetate, methanol). Antibacterial activity of the extracts was performed using 7 bacteria by disc diffusion method. According to the results of the study, highest the According to the results, B. subtilis with the greatest sensitivity to green algae and U. intestinalis</em> and U. linza</em> and P. aeruginosa</em> bacteria most resistant to most algae species studied shown. The findings of the study showed that green algae, brown algae and red to have strong antibacterial effects.

The purpose of this study was to determine antibacterial activity of the marine algae. Different algae were subjected to the three solvents (n-hexan, ethyl acetate, methanol). Antibacterial activity of the extracts was performed using 7 bacterias by disc diffusion method.According to the results of the study, the algae Ulvalinza and Ulvaintestinalis had the highest antibacterial effect against positive gram bacteria especially, Bacillus subtilis. The results showed that all macroalgae ethyl acetate and n-hexan extracts had the considerable activity in the antibacterial. The results of the study showed that green, brown and red algeahave strong antibacterial effects.

Fish epidermal mucus and its components provide the first defense line against pathogens. This study was conducted to evaluate the effects of different levels of Lactobacillus acidophilus on antibacterial activity, MIC and some immune parameters of mucus in Puntius tetrazona. Six hundred and thirty fish (0.5 ± 0.03 g) were randomly distributed in 9 aquarium for 3 treatments with 3 replicates (n=70). Fish were fed for 90 days with probiotic supplemented diets (0, 1.5×108and 3×108). At the end of the experiment antibacterial activity against Gram-positive and Gram-negative pathogen Streptococcus faecium and Escherichia coli, respectively, MIC, alkaline phosphatase activity and mucus protein levels were measured. A disk diffusion and microdilution method was used for antibacterial determination. Growth inhibition zone diameters of mucus significantly increased against both bacteria along with increase of probiotic concentration. The serial dilution of 12.5, 25, 50, 100, 200 µl/ml were considered. Alkaline phosphatase activity and mucus protein levels showed a significant differences between probiotic fed fish and control group (P

With respect to the usefulness of lichens in the traditional medicine in different parts of the world، identification of lichens and studying their antimicrobial effects are of particular importance. After collecting lichen samples، the methanol extracts were prepared and the effects of dilutions extracts on six pathogenic bacteria to method disc diffusion and the antibiotic Methicillin، Clindamycin، Sterptomycin and Ampicillin were compared to a positive control. Then، the MIC and MBC were determined. Diameter investigation showed that acetone extract of the lichen on the bacteria did not have any affect. Methanol extracts of lichens Fulgensia fulgens (Sw.) Elenkin had significant antibacterial activity. Discussion and Among the lichens we studied، only Fulgensia fulgens had. Therefore، the methanol extracts of Fulgensia fulgens could have antibacterial effects in the treatment of bacterial infections and thus could be replaced by chemical drugs.