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

In this research, the presence of effective compounds and antibacterial properties of extracts of three species from the Apiaceae family (Zeravschania membranacea, Zeravschania aucheri, and Anthriscus nemorosa) in the protected area of Kosalan in Kurdistan province has been investigated.In this study methanolic extract of the plant was prepared in different concentrations. Qualitative assessment for secondary metabolites was performed using several pharmacognosy tests from the literature. Evaluation of the antimicrobial property of the studied plants was done by disk diffusion and dilution methods. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of extracts were determined on Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa using dilution method. Based on qualitative test results, the presence of the highest number of secondary metabolites in Zeravschania aucheri, including tannin, saponin, phenol, glycoside, flavonoid, and phlobatannin. Although the presence of phenol and flavonoid was confirmed in all species, the alkaloid test was positive only in Zeravschania membranacea. The results of the antimicrobial tests showed that the most zone of growth inhibition of bacteria was related to the Zeravschania membranacea extract at a concentration of 400 mg on the Staphylococcus aureus strain (12 mm) and the Zeravschania aucheri extract did not cause sensitivity to the proliferation of all three studied strains at different concentrations. Presence of alkaloid compounds in Zeravschania membranacea could be a reasons for inhibiting the proliferation and growth of bacteria. Also, Zeravschania membranacea extract showed the lowest levels of MIC= 12.5 and MBC= 25 on Staphylococcus strain.

Milk thistle with its active ingredient silymarin, is effective in treating various liver diseases and has antimicrobial properties. An experiment aimed at study of the chemical compositions and antimicrobial activity of alcoholic extract of milk thistle seed on 8 species of gram-positive bacteria, Staphylococcus aureus, Bacillus cereus, gram-negative bacteria, Salmonella enterica, Proteus mirabilis, Escherichia coli (E.coli), Shigella Dysenteria, Klebsiella Pneumonia and Pseudomonas aeruginosa. by using disk diffusion and macrodilution methods was conducted based on a completely randomized design in the veterinary laboratory of Miyaneh Branch of Islamic Azad University in 2017. The composition of methanolic extract of milk thistle seeds were evaluated using HPLC and the presence of two substances, silybin A and B, were identified as the main constituents of silymarin. In the antibacterial test, methanolic extract of milk thistle seeds was effective against Staphylococcus aureus, Bacillus cereus, Salmonella enterica, Proteus mirabilis and Escherichia coli but had less inhibitory effect compared to Gentamicin and Ampicillin. In disk diffusion, Staphylococcus aureus had the highest inhibitory zone and the highest MIC and MBC. In Bacillus cereus and Salmonella enterica, the growth inhibition zone diameter was approximately equal to that of Staphylococcus, and Proteus and Escherichia coli showed a smaller diameter zone than Staphylococcus. It seems that milk thistle methanolic extract contains antiseptic substances with antibacterial effects. Therefore, it is recommended to study other strains.

Today, the increasing failure of chemotherapy and antibiotic resistance displayed by pathogenic bacteria infectious agents have caused the screening of new secondary metabolites with various chemical structures of marine crustaceans, molluscs and echinoderms with desirable antibacterial activity. This study was designed to determine the antimicrobial effect of muscle wall methanol and acetone extracts of four species of sea cucumber (Holothuria arenicola, H. leucospilota, Stichopus hermanni, S.horrens) in Chabahar coasts on some rainbow trout (Oncorhynchus mykiss) pathogenic bacteria (Lactococcus garvieae, Aeromonas hydrophila, Yersinia ruckeri and Streptococcus iniae).

An experimental study was conducted at in vitro conditions. Experimental variables include sea cucumber species, different concentrations of extracts and bacterial strains. After preparing extracts of mentioned sea cucumber by maceration method, the antimicrobial effect of outcome extracts from their muscle wall were investigated by two different methods disk diffusion and well diffusion.

At acetone extract of S.horrens, the highest growth inhibition zone for Y. ruckeri and A. hydrophila bacteria at 12 mg/mL concentration in disk diffusion method (11.10 and 13.03 mm) were seen respectively. Different concentrations of methanol extract of S. hermanni, H. leucospilota and H. arenicola were inactive on the tested bacteria. While, Minimum Inhibitory Concentration (MIC) of acetone extracts of S.horrens for Y. ruckeri and A. hydrophila was 0.625 and 1.25 mg/mL respectively and Minimum Bactericidal Concentration (MBC) for Y. ruckeri and A. hydrophila bacteria were 2.5 and 2.5 mg/mL respectively in well diffusion method.Generally, it type of extract, sea cucumber species and also bacterium strain are influenced on growth inhibition zone, MIC and MBC. Acetone extract of S. hermanni and S. horrens sea cucumbers can prevent the growth of Y.ruckeri bacterium tested by both methods (disk diffusion and well).

  No study has been conducted on the antibacterial activity of sea anemone in the Persian Gulf region; thus, the aim of the present study was to investigate the antibacterial, antifungal, and cytotoxic effect of Stichodactyla haddoni from Persian Gulf. In this experimental study, sea anemone samples were collected from the coast of Persian Gulf (Hormoz Island) and their extraction was performed with organic solvents such as methanol, dichloromethane, and acetone. The effect of the extract obtained on human pathogenic bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, and fungus strains such as Candida albicans, Aspergillus niger was tested, using agar disk diffusion method. The cytotoxicity of this anemic was evaluated, using brine shrimp test (BST) method on Artemia salina. The data were analyzed by SPSS 19, using Probit regression test. The extracts studied in this study showed little anti-bacterial effect. In antifungal assay, inhibition zone was showing maximum of 17mm at 16µg concentration against Aspergillus niger of acetone extract of S.haddoni. The methanolic extracts of S.haddoni tissue had a higher cytotoxicity with less LC50 (609 330/μg/ml) than acetone and diclormethanic extracts. Methanolic, acetone, and diclormethanic extracts, from S.haddoni have an antifungal effect on their antibacterial properties. It also has significant cytotoxic effects, which is higher in methanolic extract than acetone and diclormethanic extracts.

Bacterial resistance to antibiotics increased the importance of developing novel antibacterial agents. Silver nanoparticles could be considered as one of the most important antibacterial agents. Regarding to the environmental concerns of widespread application of silver nanoparticles, the use of green methods for synthesis of the nanoparticles can lead to less concerns and to develop the nanoparticles with improved properties.
The ethanolic extract of Taxus baccata leaves was prepared and used in different concentrations for reduction of silver nitrate and synthesis of silver nanoparticles. The resulted nanoparticles were characterized by different methods including UV-Vis spectroscopy, Transmission electron microscopy, FT-IR, DLS, and Zetasizer. The antibacterial activity of silver nanoparticles was finally investigated using disk diffusion assay and minimum inhibitory concentration assay.
The ethanolic extract of T. baccata displayed high potential to synthesize high quality and stable silver nanoparticles with size below 50 nm. The nanoparticles displayed considerable antibacterial effect on all three tested bacteria. Minimum inhibitory concentration of 50 µg/ml obtained for S. pyogenes (ATCC 1447) and 25 µg/ml for E. coli (ATCC 25922) and S. aureus (ATCC 25923).
Discussion and The use of biological compounds especially plant extracts instead of dangerous and toxic chemicals for synthesis of silver nanoparticles could be considered as alternatives to reduce the environmental concerns of these nanoparticles. With respect to the considerable antibacterial activity of the nanoparticles synthesized with the present method, the nanoparticles can be used for different medical, food, and industrial applications.

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.

Considering the importance of rapid determination of antibacterial susceptibility of bacteria، isolated from infectious diseases for the selection of appropriate therapy as soon as possible and increasing the success of therapy، decreasing unnecessary use of antibacterial agents and side-effects، and lowers the overall healthcare costs. We have designed and evaluated a rapid antibacterial susceptibility medium which is based on a rapid colorimetric medium that indicates growth by changing its color. In this study، we have assessed antibacterial susceptibility patterns of non-fermentative bacteria and Enterobacteriaceae isolated from clinical samples by rapid colorimetric medium according to standard CLSI method. Colorimetric medium proved to be a reliable rapid test for determining antibacterial susceptibility testing، between two methods total agreement was 92. 93% for Entrobacteriacea and 90. 46% for non-fermentative bacteria. Major discrepancy was 3. 28 % for non-fermentative bacteria and 3. 52% for Enterobacreiacea. Colorimetric medium makes results available between 68- hours. It can be considered as a novel and reliable quick method for the assessing of bacterial susceptibility to antibiotics.