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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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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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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.