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Minimum inhibitory concentrations (MIC) of some essential oils and citric acid were determined against two micro-organisms associated with spoilage of orange juice (Saccharomyces cervisiae and Leuconostoc mesenteroids) and against four unidentified microorganisms isolated from citrus surface and spoiled orange juice. MIC for limonene were obtained less than 5% w/v aqueous against Saccharomyces cervisiae and Iso-2.Lianalool minimum inhibitory concentrations was less than 5% w/v aqueous for Leuconostoc mesenteroids. MIC for other microorganisms and essential oils and citric acid were determined more than 5 % w/v aqueous. Survivor Curve testing was conducted on 6 microorganisms.

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Aims: Nowadays, treatment of bacterial infections is one of the most important challenges in the world. Medicinal plants offer a great hope to overcome these needs because of their chemical diversity and their significant role in the drug development. The aim of this study was to evaluate the in vitro antibacterial activity of the thyme (Thymus vulgaris) essential oil against Mycobacterium tuberculosis.
Materials and Methods: In this experimental study, thyme herb plants were collected and thyme essential oil was extracted. The Minimum Inhibitory Concentration (MICs) tests were performed to determine the antimicrobial activity of Thymus plant against the first (Isoniazid, Rifampicin, Ethambutol) and second (Cycloserine, Streptomycin, Kanamycin) drug antibiotics of mycobacterium. Data were analyzed by SPSS 21 software, using one-way ANOVA test.
Findings: The MICs for Isoniazid, Ethambutol, Streptomycin and Cycloserine were less than 10µg/ml and the MIC values for Rifampicin and Kanamycin were 40µg/ml. The limits of minimal inhibitory concentration of essential oil was between 0.5-40µg/ml (p<0.05).
Conclusion: Thyme essential oil has antibacterial activity against Mycobacterium tuberclusis.

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Background: Aureobasidin A is known as a cyclic depsipeptide antibiotic with toxic effects against yeasts such as Candida spp at low concentration. Combination therapy is used as a conventional treatment for fungal infections, especially drug-resistant cases. The current study aimed to investigate the combined effects of fluconazole and Aureobasidin A on fluconazole-resistant C. albicans isolates using broth microdilution method.
Materials & Methods: Antifungal activity of Aureobasidin A (AbA) compared to fluconazole against C. albicans ATCC 76615 strain was determined using the standardized broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI, document M27-Ed4) guidelines. The checkerboard method was used to test the combined effects of Aureobasidin A and fluconazole. The synergy, indifference, and antagonism were defined based on the fractional inhibitory concentration values below 0.5, 0.5-4, and more than 4 μg/mL, respectively.
Findings: MIC50 and MIC90 evaluations of Aureobasidin A and fluconazole were done at concentrations of 0.25-2 and 32-64 μg/mL against C. glabrata isolates, respectively. The synergy between fluconazole and Aureobasidin A was observed against Candida isolate. A reduced MIC was demonstrated against C. albicans isolate when fluconazole was combined with Aureobasidin A at 4 to 0.12 μg/mL concentrations.
Conclusion: The present study findings revealed that Aureobasidin A combined with fluconazole exhibited potent inhibitory effects against fluconazole-resistant C. albicans isolates. Further studies is recommended to investigate the synergistic effects of Aureobasidin A and other antifungal drugs.

 

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  Sodium diacetate is a safe chemical presevative which is used as an inhibitor against mould, yeast and some bacteria. In this study anti-microbial effect of sodium diacetate on preventing the growth of some spoilage microorganisms in carbonated beverages was investigated by broth diulation suceptibility test in medium.  At the concentrations of 10¹, 10², 10³ and 10⁵ cells of Saccharomycess cerevisiae per ml 156, 313, 1250 and 5000 ppm of sodium diacetate were respectively determined as the minimum inhibitory concentrations (MIC) preventing growth of the yeast. As for Candida krusei, 625, 1250, 2500 and 5000 ppm of sodium diacetate were MIC inhibiting the growth of the yeast at concentrations of respectively 10¹, 10², 10³ and 10⁵ cells/ml. 2500 and 5000 ppm of sodium diacetate were determined as MIC inhibiting the growth of Leuconostac mesenteroides at the concentrations of respectively 10², 10⁴ bacteria/ml, and for 10² bacteria/ml of Lactobacillus delbrukii was prevented by adding 2500 ppm sodium diacetate. No inhibitory effects of different concentrations of sodium diacetate observed at none of the prepared spore suspension of Aspergilus niger, so no concentrations of sodium diacetate were determined as MIC for this species of mould.The results show that sodium diacetate has inhibitory effects on the above selected yeast and bacteria but no inhibitory effects on the mould of Aspergilus niger.  

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Aims: The present study intends to assess the toxicity of CuO and ZnO nanoparticles (NPs) at laboratory conditions on some pathogenic bacteria for the reared fish, as well as, a bioassay on rainbow trout.
Material & Methods: For this purpose, the sensitivity of them to the mentioned NPs with a reference antibiotic (florfenicol) was assayed through the well diffusion method, as well as, minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) were determined by microdilution technique. On the other hand, the lethal toxicity test has been accomplished to the calculation of median lethal concentration (LC50) on some rainbow trout (55.3±7.6 g) in static condition for the 96 consecutive hours. We use one-way ANOVA and Probit regression in order to data analysis.
Findings: Results show that NPs of copper oxide and zinc oxide could significantly inhibit the growth of Streptococcus iniae or kill it at 0.18 and 0.24 µg/ml and more, respectively. The comparison between LC50-96h quantities of CuO NP (107.4 µg/l) and ZnO NP (102.3 µg/l) indicated that the CuO NP has more toxic potential.
Conclusion: According to the laboratory findings, the susceptibility of S. iniae and L. garvieae to ZnO NP were close to florfenicol. The mortality in the fish species due to lethal toxicity would occur if the effective concentration of NPs on the bacterial pathogenic agents being used directly.

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Background: The present investigation aimed to survey the in-vitro inhibitory effects of nitroglycerin against Candida albicans, Trichophyton rubrum, and Aspergillus flavus.
Materials & Methods: In the current investigation, 99 fungal isolates were gathered from patients referred to the Medical Mycology Laboratory of Tehran University of Medical Sciences. The disk diffusion method was done based on Clinical and Laboratory Standards Institute (CLSI) M44-S2 guidelines. Also, the microdilution method was performed base on CLSI guidelines for filamentous fungi (document M38-A2) and yeasts (document M27-A3).
Findings: In the disk diffusion method, all isolates of C. albicans (n=33, 100%) and A. flavus (n=33, 100%) showed sensitivity to nitroglycerin, whereas all isolates of T. rubrum (n=33, 100%) showed resistance to nitroglycerin. On the other hand, in the microdilution method, the minimum inhibitory concentration (MIC) of nitroglycerin against C. albicans and A. flavus isolates was 0.5 mg/mL, whereas the MIC of nitroglycerin against T. rubrum was 0.12 mg/mL.
The results showed that the MIC of nitroglycerin against dermatophytes was about one-quarter of its MIC against C. albicans and A. flavus, and this difference was statistically significant (p< .05).
Conclusion: Considering the potential and efficacy of nitroglycerin against yeasts and filamentous fungi (saprophytes and dermatophytes), complementary in-vivo and in-vitro studies should be done.

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Klebsiella pneumoniae is a gram-negative bacillus of the Enterobacteriaceae family. Despite being part of the natural human microflora, this is an opportunistic pathogen and a major cause of nosocomial infections. The increased emergence of multidrug resistance in Klebsiella pneumoniae has limited the treatment options for this bacterium. Carbon nanotubes (CNT), by improving the stability and solubulity of drugs, could increase the effectiveness of drugs for treatment. The aim of this study is to investigate the antibacterial effect of nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) on Klebsiella pneumoniae isolated from clinical specimens. For the strain confirmation, biochemical ,API20E kit, and additional differential tests were performed, and antibiotic susceptibility test was performed by the disk diffusion method. The studied strain showed a resistance to all antibiotics such as cefepime.The minimum inhibitory concentration (MIC) was determined using the antibiotic micro dilution method. The MIC was determined in five effect modes including antibiotic (Ab), nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) , nanofluid containing multi-walled carbon nanotubes (CNT-NF) ,Ab in combination with f-CNT-NF and Ab with CNT-NF. Nevertheless the individual effects of 10 µg mL^-1 cefepime or 80 µg of nanofluid with f-CNT-NF did not inhibit the growth of the bacteria, but the co-administration of 10 µg mL^-1 cefepime with 80 µg of the f-CNT-NF could inhibit the bacteria`s growth. It was concluded that f-CNT-NF could be more effective in drug delivery at lower concentrations than the free state, which could be used as a tool for optimal drug delivery.

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The present study aimed to isolate the steroids and fatty acids from the liver of the Persian Gulf spot tail shark Carcharhinus sorrah and to assess their antifungal activity. Extraction was done by methanol 70% and then, the lipids were separated through column chromatography with silica gel. Identification of the extracted lipids was done by thin layer chromatography and gas chromatography coupled with mass spectrometry. Then, antifungal activity of the steroids was investigated through determining the minimum inhibition concentration and minimum fungicidal concentration by tubular dilution method against Aspergillus fumigatus and Candida albicans. Identification of the extracted compounds by GC-MS confirmed the presence of these steroids in the shark liver. The identified steroids included compounds of Y-Sitosterol, Desmosterol and Squalene, which showed different results regarding the growth inhibition and fungicidal effects against the microorganisms at different experimental doses. Desmosterol and Squalene at minimum concentration induced the highest inhibitory effect on the fungus but Y-Sitosterol induced the highest inhibitory effect on the yeast. Squalene showed fungicidal effect only on the fungus and totally, A. fumigatus was more sensitive to the antimicrobial activity of the liver compounds than C.  albicans. In conclusion, promising results were found regarding the antimicrobial activity of the lipid compounds derived from Persian Gulf shark liver, revealing the importance of more comprehensive investigations of these natural compounds for the synthesis of biomedicines from the marine organisms.
 

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The aim of this study was to evaluate antibacterial activity of aqueous extract of castor seeds (two varieties, Mashhad and Isfahan) on Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922 and Listeria innocua ATCC33090 as food borne pathogens. The sensitivity of the microorganisms was evaluated using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). According to disc diffusion method the most resistance was observed by gram positive bacteria (Listeria innocua, Staphylococcus aureus) where as, the most sensitivity was observed by Escherichia coli.In disc diffusion method as a positive control Erythromycin, Gentamicin and chloramphenicol were used on Listeria innocua, Staphylococcus aureus and Escherichia coli in which deterrence diameters were 13mm, 22mm, 30mm, respectively. The experiments of MIC, MBC were performed in triplicate. According dilutions which were prepared in MIC experiment the ranges of aqueous extract of castor from Mashhad on Listeria innocua and Staphylococcus aureus was between 40 to 160 mg/ml. This range for Escherichia coli was less than 40 mg/ml. But for aqueous extract in castor seeds from Isfahan was between 20 to 40 mg/ml on  Listeria innocua, between 40 to 80 on Staphylococcus aureus and between 20 to 80 mg/ml on Escherichia coli. Also MBC test were measured around 160 mg/ml in castor seeds of Mashhad and Isfahan. The both of aqueous extract of castor seeds from Mashhad and Isfahan had strong antibacterial activity and aqueous extract from Isfahan had more inhibitory effect than the aqueous extract of Mashhad.  

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In a marine environment, the biofilm formed on the submerged surfaces leads to fouling of larger organisms. This leads to many environmental and economic problems for the marine industries. Due to the harmful effects of chemical antifouling, the development of environmentally friendly anti-biofilm strategies can be an important step to control fouling.
Therefore, the present study was performed with the aim of isolation of biofilm-forming bacteria from Persian Gulf waters and investigating the antimicrobial effect of thymol against selected bacteria.82 bacterial were isolated and their ability to form biofilm was measured. Among these, 5 isolates were selected and identified using 16S rRNA sequences. The results showed that the 5 selected isolates belonged to the Proteobacteria (genus Vibrio, Kangiella and Psudoaltromonas). In the study of the antibacterial effect of thymol, K. spongicola (PH1) showed the highest sensitivity in disk diffusion method (with a growth inhibition zone diameter of 18 ± 0.57 mm). The minimum inhibitory concentration and minimum bactericidal concentration (at 31.5 and 62.5 μg /ml, respectively) were obtained against the same bacterium. The inhibitory thymol on biofilm formation and performed biofilm by Psudoaltromonas sp. (PH18) showed that thymol at concentrations sub-MIC is able to inhibit biofilm formation. The effect of thymol on the performed biofilm at concentrations higher than MIC is noticeable. Based on the results, due to the anti-biofilm activity of thymol against marine bacteria, its use as a natural compound in antifouling coatings can be suggested.

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In recent years, multiple drug resistance in human pathogenic microorganisms have developed due to indiscriminate use of commercial antimicrobial drugs commonly used in the treatment of infectious diseases. This situation forced scientists for searching new antimicrobial substances from various sources, like medicinal plants, which are the good sources of novel antimicrobial chemotherapeutic agents. In this study, the antibacterial effect of Cardin leaf was investigated. Hydroalcoholic extract of this plant was prepared at concentrations of 0.390 to 100 mg/ml and antimicrobial effect of extract were tested with disk diffusion and agar-well diffusion diffusion method against Listeria monocytogenes, Salmonella enteritidis and Pseudomonas aeruginosa strains. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the Cardin extract were investigated by dilution method. In the disk and well diffusion methods, the highest effect of extract on the bacteria was observed at concentration of 100 mg / ml, with the highest diameter of deterioration hole. Of course, the effect on gram-positive bacteria was more than gram negative. The inhibitory concentration of extract (MIC) on Listeria monocytogenes, Salmonella enteritidis and Pseudomonas aeruginosa was 12.5, 25 and 50 mg/ml and the MBC was 50, 100 and 100 mg/ml, respectively. The results showed that effect of Cardin extract on gram-positive bacteria was more than gram negative and the diameter of the non-growth halo increased with increasing concentrations of the extract.
 

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In this research extraction of Salvia leriifolia leaf was carried out using two extraction methods including traditional solvent extraction (with different solvent ratio of water /ethanol 50:50, 60:40 and 70:30 at temperature 70, 80 and 90 ºC and time duration of  30, 75 and 120 min), and superheated solvent extraction (at temperature 130, 145 and 160 ºC, time duration of 10, 20 and 30 minutes and solvent ratio of water/ethanol 60:40, 80:20 and 100:0) and the antimicrobial activity of extracts against some of food microorganisms  using minimum inhibition concentration and minimum bactericidal concentration methods were measured. In both extraction methods, the MIC of most microorganisms was 0.5 mg/ml, while the MBC, depending on the microorganism, was between 5 and 500 mg/ ml. In the conventional solvent extraction procedure, the treatment was carried out at a temperature of 80 ° C, 75 minutes, and equal ratio of two solvents, and in superheated solvent extraction method, treatment including temperature of 160 ° C, time of 20 minutes, and water/ Ethanol ratio of 80 to 20 showed the most antimicrobial activity. Based on the results, it can be stated that the type of plant extraction method has a significant effect on inhibiting or preventing the growth of food borne  or spoilage microorganisms, and if any of the plant extraction technique are optimized, they can be better used to increase the shelf life of food.

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The inhibitory effect of Ulva lactuca (Chlorophyta), Dilophus spiralis (Phaeophyta) and Janiarubens (Rhodophyta) marine algae species has been evaluated against 2 Gram-positive bacterial (Streptococcus pyogenes and Micrococcus luteus); 2 Gram-negative bacterial (Shigella flexneri and Vibrio cholerae) and 2 fungal (Candida albicans and Aspergillus niger) isolates using aqueous and six organic extracts (methanol, ethanol, chloroform, acetone, ethyl acetate and hexane). Data revealed that the M. luteusbacteria was the most sensitive pathogen by showing the highest zone of inhibitions (ZIs) of 17 mm with the lowest Minimum Inhibitory Concentration (MIC) of 26.7 µgmL^-1 and the lowest Minimum Bactericidal Concentration (MBC) of 53.3 µg mL^-1 with chloroform D. spiralis extract. Whereas, aqueous extracts were not active against all selected pathogens regardless of the examined algae species. Based upon data presented herein, chloroform D. spiralis extract was the most active against examined pathogens. Thereby, future performance research in D. spiralisis requested due to their high effectiveness as a cheap antimicrobial agent. 

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In order to reduce the economic losses and life risks caused by microbial pathogens, the use of natural substances as antimicrobial compounds seems to be an effective way to control the presence of pathogenic bacteria. In this study, the chemical composition of onion essential oil was determined by gas chromatography–mass spectrometry (GC-MS). The methods in disk diffusion agar (DDA) and well diffusion agar (WDA) were used to investigate the inhibition zone diameter, micro-dilution broth was used to measure the minimum inhibitory concentration (MIC) and pour-plate technique was also used for minimum bactericidal/fungicidal (MBC/MFC) concentration. A total of 20 chemical volatiles (approximately 100% of onion essential oil compounds) were identified. The compounds Trisulfide dipropyl, Disulfide dipropyl, n-Decane and Furfuryl methyl sulfide with 20.67, 16.18, 13.51 and 10.23% of the main constituents of onion essential oil, respectively. The results of WDA showed that onion essential oil had the most and the least effect on Gram-positive bacteria Staphylococcus aureus with a diameter of 15 mm and Gram-negative bacteria Pseudomonas aeruginosa with a diameter of 10 mm, respectively. The results of MIC onion essential oil for Staphylococcus aureus, Listeria innocua, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa and Candida albicans 512, 512, 512, 512, 512 and 1024 mg/mL, respectively. In general, the results of this study showed that the antimicrobial effect of onion essential oil can be somewhat different depending on the type of microorganism.

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Plant diseases cause severe damage to agricultural production and need to be effectively managed. The economic importance of the plant diseases and lack of effective control measures have led to many research in this field. Nanotechnology is one of the new techniques for disease control. The purpose of this study was to evaluate the antibacterial effects of copper and iron Nano­Particles (NPs) against a Xanthomonas campestris strain, as well as the study of these nanoparticles’ effects on expression of the pathogenic gene hrpE. The Zero-Valent Iron (ZVI) and copper nanoparticles were synthesized by chemical reduction method. Different concentration of nanoparticles of Fe and Cu were used in bacteria plate culture and the Minimum Inhibitory Concentrations (MIC) as well as Minimum Bactericidal Concentration (MBC) were determined using colony count and optical density methods. The effect of nanoparticles on pathogenic gene expression hrpE was studied using Real- Time PCR. Xanthomonas campestris strain exposed to zero-valent iron nanoparticles showed that the growth rate was increased with increase in the concentration of nano-iron. But, the growth percentage of bacteria Xanthomonas campestris was reduced with increase in the concentration of nano-copper. The expression levels of pathogenic gene expression hrpE were increased 9 and 3 fold for copper and iron, respectively. Copper and iron nanoparticles showed different effects on Xanthomonas growth.

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Although chemical antifungal preservatives are often used in various food products, the use of these substances has been limited due to their harmful effects on human health and the environment. Researchers have recently sought to replace these chemical compounds with natural and less dangerous substances. In this regard, using essential oils of medicinal plants can be considered a suitable alternative due to fewer side effects. Therefore, in the present research, after preparing the Badrashboo plant from the fields of Golmarz village located near Urmia city and drying it, extracting the essential oil from the Badrashboo was carried out using a Clevengerger, and the antifungal effect of Badrashboo essential oil on some important fungal strains with disc diffusion agar and well diffusion agar, minimum inhibitory concentration, minimum fungicidal concentration and the interaction of Badrashboo essential oil with Nystatin were performed. The results of disk diffusion agar and well diffusion agar tests showed that Badrashbo essential oil had a significant antifungal effect on all studied fungal strains. The results of the minimum inhibitory concentration of essential oil for strains of Saccharomyces cerevisiae, Candida albicans, Aspergillus niger, Fusarium solani, and Penicillium expansum were 8, 16, 2, 8, and 4 mg/ml, respectively. The minimum fungicidal concentration for the mentioned strains was 32, 64, 8, 16, and 32 mg/ml respectively. Also, the results of the interaction of Badrashboo essential oil with Nystatin indicated the synergistic effect of Badrashboo essential oil with Nystatin. Considering the significant antifungal effect observed for Badrashbo essential oil in the present study, it can be used in the food and pharmaceutical industries.
 

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Silver Nanoparticles (AgNPs) are widely used in medical and pharmaceutical applications due to their antimicrobial properties. In this study, Ag-NPs were synthesized using Viola tricolor aqueous extract as a reducing and capping agent. The presence of synthesized Ag-NPs was first confirmed with UV-Visible, SEM, TEM, XRD, and FTIR analyses, and then their antimicrobial characteristics were studied based on the Minimum Inhibitory Concentration (MIC). The SEM analysis showed that the synthesized AgNPs were spherical in shape. The particle size histogram revealed that the average particle size of the AgNPs was 49.45 nm. Findings from the FTIR and UV-Vis spectra showed the successful formation of Ag-NPs because the functional groups involved in the synthesis process and adsorption peaks were well developed. Furthermore, the Ag-NPs had a peak absorption at 420 nm in the spectrometry. MIC results showed the strong antimicrobial effects of the synthesized Ag-NPs. Results of the Minimum Bactericidal Concentration (MBC) revealed the dose-dependent cytotoxicity of the Ag-NPs. Nanoparticles could exert the inhibitory effect of DDPH free radicals in a dose-dependent manner. Methyl tetrazolium (MTT) results showed that silver nanoparticles had a dose-dependent cytotoxic effect and significantly reduced cell survival. The IC50 values for Ag-NPs and the extract were 11.83 and 204.4 μg mL^-1, respectively. This study showed a higher cytotoxic effect of the green synthesized nanoparticles on hepatocellular carcinoma cells than the extract. Consequently, the biosynthesis of Ag-NPs using aqueous extract of V. tricolor is clean, inexpensive, and has antibacterial, anticancer and antioxidant activities. Hence, it can be used as a drug candidate.