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  Abstract Background: Streptococcus mutans in the oral cavities sable to produce mutacin (bacteriocin-like substances) with antibiotic properties. The aim of this study was to investigate the frequency and expression of genes encoding mutacins typeI, II, III and IV and also two of 8 genes in a cluster encoding the putative bacteriocins, the designated bsm 283, bsm 299, bsm 423, bsm 1889c, bsm 1892c, bsm 1896, bsm 1906c and bsm 1914, were also screened by PCR and specific primers for each type of mutacin biosynthesis gene and then mutacin activity against the indicator strains determined. Methods : In this study, dental clinic samples were collocated; Streptococcus mutans was detected using biochemical tests and molecular methods (PCR). Frequency of mutacin biosynthesis genes types I, II, III and IV, bsm299 and bsm1899 were measured by PCR, using specific primers for each type of mutacin biosynthesis gene. Furthermore, the antimicrobial spectra of Streptococcus mutans isolates against other indicators, including Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella typhi, Pseudomonas, Escherichia coli were evaluated using well diffusion, disk diffusion and the minimal inhibitory concentrations (MICs) methods. Results : Out of 56 samples collected from patients referred to Milad Hospital dental clinic on October 2011 and three private dental clinics on November 2011, 24 strains of Streptococcus mutans produced mutacins. 67.52% of the strains had a wide antimicrobial spectrum and 37.5% of 67.5% had a high frequency of genes with more inhibitory activity against, Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis respectively that are more related to putative bacteriocins. The expression frequency of the bsm gene (putative bacteriocins) was higher than that of the characterized mutacins types (I–IV). The lowest dilution rate mutacin was found against Staphylococcus epidermidis (0.0625 unit/mL). Conclusion : These findings suggested that all putative bacteriocins may represent a large repertoire of inhibitory substances produced by Streptococcus mutans. Therefore, the high diversity of mutacin-producing phenotypes, associated with high frequency of expression of the biosynthesis genes screened and wide antimicrobial activity against Staphylococcus epidermidis could be used as safe antimicrobial agents in treatment of superficial infections such as, removing the pimple caused by Staphylococcus epidermidis.

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Background: The main objective of this study was to determine the prevalence and antimicrobial resistance profiles of the main bacteria which are responsible forurinary tract, blood stream, cerebrospinal fluid, lower respiratory tract, and wound infections in Hamadan province in the west of Iran.
Materials and Methods:In this study,a total of 773 urinary tract, 273 blood stream, 13 cerebrospinal fluid, 408 respiratory tract, and 147 wound positive samples were collected from patients who referred toBesat hospital from April 2013 to October 2014.Antibiotic susceptibility testing was performed by Modified Disk Diffusion Method (MDDM) against different classes of antibiotic.
Results: The most common pathogens isolatedfrom urine tract, blood stream, cerebrospinal fluid, lower respiratory tract, and wound infections wereE. coli 425 (54.9%),S. aureus 68 (24.9%),Klebsiellaspp. 3 (23%), P. aeruginosa 110 (26.9%), and S. aureus 30 (20.4%) respectively.The overall prevalence of resistance to the antimicrobial agents testedin various clinical specimens is discussed in this study.
Conclusion: The high resistancerate was observed in our study to most used antibiotics. Therefore, setting up a comprehensive surveillance systemis need to evaluate the distribution of organisms isolated and their drug resistance pattern over different period of time and place of Iran.

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The cypress family, Cupressaceae, has a global dispersion. Currently, endophytic microorganisms from plants are being investigated for their diversity and bioactivities. Here, we aimed at exploration and characterization of cultivable endophytic fungi from foliar tissues of Cupressaceae, i.e. Cupressus arizonica, C. sempervirens var. cereiformis, C. sempervirens var. fastigiata, Juniperus excelsa, Juniperus sp. and Thuja orientalis. Asymptomatic fresh foliar tissues, collected from mature healthy plants, were sterilized and the inner layers were plated on culture media at 26-28 °C for 2-12 weeks, until fungal colonies emerged and were purified. Endophytic Penicillia i.e. Penicillium aurantiogriseum, P. chrysogenum, P. commune, P. echinulatum, P. expansum and P. viridicatum were the dominant fungi recovered. Results indicated that both host plant and geographical location of sampling affected the biodiversity and bioactivity of endophytic Penicillia. Results also indicated that those endophytic Penicillia had significant bioactivities. According to our results, both intra-and extra-cellular secondary metabolites from all isolated Penicillia had significant cytotoxic and antifungal effects against the model fungus Pyricularia oryzae and cypress fungal phytopathogens Diplodia seriata, Phaeobotryon cupressi and Spencermartinsia viticola. Further studies indicated the significant antimicrobial bioactivities of superior Penicillia against model bacteria. Altogether, this study highlights, for the first time, the biodiversity of endophytic Penicillia from Cupressaceae plants and documents their significance for agrochemical/drug discovery and for plant disease biocontrol.  

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The control of bacterial diseases of fish has always been one of the most important problems of aquaculteriets in recent years. One of these problems is bacterial resistance. Using antibiotics can cause problems for consumers. Therefore, the use of new antimicrobial agents with minimal complications is common. In the present study, using the acid-thermal method, the bentonite structure was modified and the chitosan and bentonite hybrids were modified in the stage of development. The structure of the compounds was studied using the Infrared Fourier Transform Spectrometry (FTIR), Surface Electron Scanning Microscopy (FE-SEM) and X-ray diffraction spectroscopy (EDX). Antimicrobial activity of two types of modified bentonite on gram negative bacterium Aeromonas hydrophila was studied in vitro using two methods of disk diffusion and microdilution. The results of the disc diffusion method showed that the antimicrobial compounds produced had antibacterial properties in experimental conditions against the Aeromonas hydrophilia bacteria. Antimicrobial activity (MIC and MBC) was determined using microdilution and clonal counting in Agar culture medium. The results showed that the modified compound with the acidic method had MBC of 28.57 and 14.28 mg / L for Aeromonas hydrophila bacteria in 10 minutes and 30 minutes. For chitosan and modified bentonite composite, MBC was 14.28 mg / ml for Aeromonas hydrophila bacteria in 10 and 30 minutes. The results of this study showed that modified bentonite and composite compounds have strong antimicrobial effects and can remove pathogens in laboratory conditions and can be used as new compounds to control pathogens in breeding systems.

 

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Background: Gram-negative organisms producing Extended-spectrum beta-lactamases (ESBLs) are presented as a global problem. Klebsiella pneumoniae is considered as one of the most important microorganism of this group. The prevalence rate of K. pneumoniae species is increasing, and this increase is higher in the ESBL group, indicating the increase in antibiotic resistance. We must have sufficient knowledge about regional antibiotics resistance in order to monitor the prevalence rate and antimicrobial resistance among the isolates by appropriate treatment. In this regard, the objective of our study was to evaluate antimicrobial susceptibility among K. pneumoniae isolates by E-test method in Khatam ol Anbia hospital during 2015.
Materials and methods: This descriptive cross-sectional study was carried out during 2015.  All clinical samples were collected from intensive care unit (ICU) and general wards of Khatam ol Anbia hospital. All of the K. pneumoniae strains were detected by biochemical and microscopic tests. Antimicrobial susceptibility and minimum inhibitory concentration (MIC) were determined by disk diffusion and E-test methods. Descriptive statistics was used to analyze data.
Results: About 62 K.  pneumoniae strains were isolated from clinical samples of ICU and general wards during one year. Of these, 38 (61.3%) isolates were isolated from intensive care unit, and 24 (38.7%) isolates were isolated from the general wards. In this review, the least resistance was related to colistin (4.8%) and Amikacin (14.5%), respectively, and the most resistance was observed to the antibiotics of ciprofloxacin (66.1%), ceftriaxone (62.9%) and gentamicin (59.7%), respectively. Resistance to imipenem was observed in 38.7% of the isolates.
Conclusion: The current study demonstrates that antibiotic resistance pattern is changing, and resistance to imipenem and colistin is rising, so this should be considered as a serious risk for admitted patients in hospital.  

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Background: Nosocomial infections have high mortality rates because of infective organisms' specific characteristics and the type of patients identified with different comorbid diseases. The aim of this study was to determine the prevalence rate  of different microorganisms and their characteristics in terms of resistance to various antibiotics.
Materials and Methods: Samples of urine, blood, abscess and wound secretion, and septum or tracheal secretions were cultured for 139 patients who were hospitalized during September 2012 to September 2014 and identified with nosocomial infection in different hospital wards. Then the type of microorganism and their antibiotic resistance were determined for each patient using culture antibiogram with disk diffusion method. Results were then analyzed using SPSS software.
Results:  The incidence of nosocomial infections was observed more in men than in women. Fever and purulent discharge from the wound site were the most common symptoms, leading to patient's hospitalization. Most patients were from the transplant and urology wards. Urinary tract, skin, and soft tissue infections (SSTI) had the highest prevalence rate in patients. Escherichia coli was the most common infectious microorganism in patients, which was sensitive to imipenem and meropenem. Kelebsiella as the next most common infectious microorganism was resistant to imipenem.
Conclusion:  The results of this study are consistent with the previous studies. Due to infectious microorganisms' resistance to antibiotics, it is recommended to reduce the consumption of antibiotics. 

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Aims: Many infectious diseases had traditionally been cured with herbal medicines. Antimicrobial agents are often produced synthetically to increase the food durability and quality. The purpose of this study was to determine the antimicrobial properties of the aqueous and alcoholic extracts of Allium schoenoprasum.
Materials & Methods: In this experimental study, after preparation Allium schoenoprasum samples, aqueous and alcoholic extracts were prepared and their minimum inhibitory concentration (MIC) was determined against Staphylococcus aureus, Bacillus cereus, Escherichia coli and Vibrio cholerae by micro broth dilution method. Erythromycin was used as the control.
Findings: The MIC of alcoholic and aqueous extracts of A. schoenoprasum was 16-256 and 32->256µg/ml, respectively and MBC of them were 32-256 and 64->256ug/ml, respectively. The A. schoenoprasum exhibited higher activity against S. aureus and B. cereus strains.
Conclusion: The extracts of A. schoenoprasum have antimicrobial effect on S. aureus, B. cereus, E. coli and V. cholerae strains in micro broth dilution method.

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Introduction: The use of antibiotics in food-producing animals has elevated concerns regarding their potential affect on human health. Resistant Salmonella may be transmitted through the food chain to humans. The aim of this study was to determine the prevalence of tetracycline resistance genes among tetracycline-resistant Salmonella enterica from Iran.
Material and methods: In this experimental study, A total of 4369 stool specimens were collected via rectal swab from hospitalized children under the age of 5 with watery diarrhea, with or without blood, mucus and stomach cramps. Antimicrobial susceptibility profiles of Salmonella isolates were performed and Minimum inhibitory concentration (MIC) of tetracycline was assessed. Bacteria were grown on blood agar at 37°C overnight, and genomic DNA was extracted. For evaluating of PCR products used of 1.5% agarose gel in TBE buffer at for 80min.
Findings: High level of resistance was observed against minocycline (78.5%), tetracycline (76.0%), nalidixic acid (66.6%) and streptomycin (42.0%). The MIC for 46.0% of the isolates was 256µg/ml, while 15.6% showed the MIC of 128µg/ml and the remaining revealed 64µg/ml MIC to tetracycline. Among the 33 tetracycline-resistant isolates the tet(A) or tet(B) genes were detected in 10 (23.8%) and 5 isolates (11.9%), respectively. The tet(A)and tet(B) genes were identified in 2 out of the 42 tetracycline-resistant Salmonella isolates (4.8%). The tet(C) or tet(D)genes were not found among tetracycline-resistant isolates.
Conclusion: Resistance to Salmonella strains is increasing. The predominant tetracycline-resistant gene is tet(A) followed by tet(B).

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The antibiotic properties of eight cyanobacteria (blue-green algae) species from Anzali Wetland was investigated on several bacterial species through vacuum distillation and simple mechanical methods. The result showed that Anabaena sp., A. variabilis, A. flos-aquae and Aphanizomenonflos-aquaehad negative effect on the growth of Staphylococcus aureusandA. flos-aquaeand A. oscillaroideshad negative effects on the growth of E. coli. The growth of Candida albicans yeast was greatly reduced by Aphanizomenonflos-aquae, A. variabilis, and A. oscillaroides. Among the investigated algae only A. oscillaroides could reduce the growth of Pseudomonassp. 

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The antimicrobial effects of essential oil isolated from Myrtus communis L. against Es-cherichia coli, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniaee, Bacillus subtilis, Bacillus licheniformis, Candida albicans and Sac-charomyces cerevisiae were studied. The disc diffusion method was used to evaluate the zone of microbial growth inhibition at various concentrations of the oil. The minimal In-hibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) of the oil were determined. The oil was found to have an antimicrobial effect. Kinetics of microbial destruction exhibited that the oil could kill microorganisms within 45 minutes of expo-sure. GC and GC/MS analysis of the oil revealed 32 components. The major components were α-Pinene (29.4%), Limonene (21.2%), 1,8-Cineole (18%), Linalool (10.6%), Linalyl acetate (4.6%) and α-Terpineole (3.1%). The high monoterpenes hydrocarbons such as α-Pinene and Limonene seem to contribute to the strong antimicrobial activity of Myrtus communis L. Further research on antimicrobial effects of essential oils with a view to sub-stituting the common chemical compounds is promising.

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There are many reports about antibacterial potency of natural honey. Theses reports are confirmed preventive efficacy of honey on various different kinds of bacteria. The most important antibacterial factors of honey are phytochemical materials.These substances are derivatives from plants flora of bee culture’s region. We designed this study in order to assess the antimicrobial efficacy of honeys produced different regions of Urmia. This investigation was performed on samples collected from 5 honey production’s  regions (Marmishoo=1;  Nazloo= 2;  Ghasemloo valley= 3;  Marghevar= 4;  Targhevar=5 ). 20 samples were collected from each region. Samples were cultured on blood agar media in order to confidence of lack of previous contamination. Then samples were cultured on standard bacterial culture include: Staphylococcus aureus (ATCC25923) , Escherchia coli (ATCC25922) , Pseudomonas aeruginosa (ATCC27853). Inhibition zone (IZ) and Minimum inhibitory concentration (MIC) were measured for each bacteria after incubation period. According to results of our experience, Targhevar honey posses more (IZ) and lesser (MIC) in compared to other samples. (p<0.05) Difference between samples is thought to be due to existence of special phytochemical substances in plant flora of Targhevar region. These materials should be extracted and collected and used in production medical honey. The selection of special region for bee keeping is very important in process of monofloral medical honey production.

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The main goal of this study was to evaluate the antimicrobial activity of Ziziphora clinopodioides against some food spoilage and pathogenic bacteria and determine Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Extract of Ziziphora was tested for its growth inhibitory and bactericidal effect on 6 Gram-negetive (Enterobacter aerogenes, Escherichia coil, Klebsiella pneumoniae, Salmonella enteriticlis, Shigella dysenteria and Pseudomonas aeroginosa) and 3 Gram-positive (Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus) species. Minimum inhibitory Concentration (MIC) was determined using dilution method and minimum bactericidal concentration(MBC) was taken from the concentration of the lowest dosed test tube showing no growth on subcultured. All of microorganisms were inhibited by the extract of Ziziphora clinopodioides except Pseudomonas aeroginosa. The MIC and MBC for Gram-negetive bacteria, including Enterobacter aerogenes, Escherichia coil, Klebsiella pneumoniae, Salmonella enteriticlis and Shigella dysenteria were 1000-2000 μg/L. The MIC and MBC for Gram-positive bacteria, including Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus, were 1000-4000 μg/L. Acording to the results of this study, It is applicable to use extract of Ziziphora as the natural preservatives and flavoring agents in food products.

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 Aims
 Urinary tract infection (UTI) is one of the most common infections worldwide. The aim of this study was to investigate the association between ESBLs genes and quinolone resistance in Uropathogenic Escherichia coli isolated from patients with urinary tract infection .
Materials & Methods
A total of 150 E. coli isolates were collected from patients with urinary tract infection referring to Firouzgar Hospital in Tehran, Iran. Antimicrobial susceptibility of isolates were determined by disk diffusion method. Double-disk diffusion test was performed for phenotypic identification of extended-spectrum β-lactamase- (ESBL) producing isolates. PCR was used for the detection of ESBL-encoding genes in addition to quinolone (qnr) resistance genes.

Findings

 There was a high resistance rate to most of the studied antimicrobial agents. Phenotypically, 75% of the isolates produced an ESBL enzyme and were resistant to different antimicrobial classes. In overall, 83% of the isolates carried ESBL genes, especially bla_TEM and bla_CTX-M  . 75% were positive for the quinolone resistance genes including qnrA , qnrB ,qnrS and qepA. These results indicate the association between the presence of various ESBLs genes and quinolone resistance in uropathogenic E. coli.

Conclusion

Resistance patterns show the increased incidence of antibacterial resistance in E. coli. Results of the current study indicate the high prevalence of ESBL-producing isolates and quinolone resistance genes. Simultaneous presence of genes responsible for antibacterial resistance has made the treatment of UTI more challenging than ever before.

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The antimicrobial and physico-mechanical properties of fish gelatin-alginate film incorporated with oregano (Origanum vulgare L.) essential oil (OEO) were assessed. The blended films were prepared with 75% fish gelatin and 25% sodium alginate and OEO (0, 0.5, 1.0, 1.5%) was added to the film solutions. Results showed that adding 0.5% OEO into films improved tensile strength about 2.54 MPa compared to the control films. The incorporation of 1.5% essential oil decreased tensile strength and the elongation percentage by 3.16 MPa and 15.59%, respectively; water vapor permeability, viscosity and opacity also significantly declined (P < 0.05). Scanning electron microscopy (SEM) of the surface of the film confirmed these results. Although 1.5% OEO-films showed higher antimicrobial activity, fish gelatin-alginate films incorporated with lower level of OEO can be can be more appropriate for food preservationl.

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The aim of this study was assess the application of carvacrol at 5 and 10% levels in production of the zein film and evaluation of its antimicrobial properties, and also kinetics release of carvacrol from active film (10%w/w) in food simulants of acetic acidand ethanol at different temperatures by using high performance liquid chromatography from. Diffusion and the activation energy (E_a) values of zein film containing 10% carvacrol were calculated based on Fick’s second law. Results showed that by increasing temperature from 4 to 37°C, the extent of releasing after 60 min in acid simulant (9.82 ± 1.34 to 40.78 ± 0.06 %(, and ethanol simulant (11.80 ± 1.34 to 47.44 ± 0.06%) was increased. The diffusion value of carvacrol at 4, 22 and 37°C in acetic acid simulant was determined 0.23, 1.20 and 6.70 m.s, respectively. The E_a value for carvacrol diffusion in 3% acetic acid simulant (72.75 kJmol^-1) was lower than in ethanol simulant (79.73 kJ mol^-1). The antibacterial activity of zein films was studied against Escherichia coli and Listeria monocytogenesin at 4 and 37°C. The zein films containing 5% carvacrol produced a good bactericidal effect. It was observed total inhibition against Escherichia coli by incorporating 10% carvacrol in zein film at both temperatures. This work suggested that the zein bioplastics containing carvacrol can be used as an active packaging for improving the safety and shelf-life of food products.

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Introduction: Nanotecnology could solve most of problem of biomedical and cause improve in health and pharmacology field. Also this industrial cause to eliminate food pathogenic bacteria.increase of food pathogenic bacteria and resistance them to different antibiotics caused usage of nanotechnology by researchr and pharmacologiests. Material and Methods:In this reseach is studied antimicrobial effect of nanoparticles of silver,TiO2 against on food pathogenic bacteria such as Staphylococcus aureus PTCC 1431 and Listeria monocytogenes by determination MIC and MBC. Result: Silver nanoparticle was synthezied with 103 nm of size and consentraion of 1 mili molar,nano TiO2 with 21 nm of size and consentrain of 1% have antimicrobial effect against on Staphylococcus aureus PTCC 1431 Listeria monocytogenes . Conclusion: Since that antimicrobial activity of silver ,TiO2 nanoprticles against on food pathogenic bacteria (Staphylococcus aureus PTCC 1431 and Listeria monocytogenes) is proved, is suggested to packaging antimicrobial food. Keywords: Silver nanoparticle,TiO2,,Antimicrobial effect, Staphylococcus aureus PTCC 1431 Listeria monocytogenes

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Aims: Helicobacter pylori is a bacterium that colonizes the gastric mucosa and is the main cause of gastritis as well as ulcer and gastric cancer. Due to the clinical significance and international increase in H. pylori multidrug resistance, it is necessary to search for new strategies improving eradication rates. Natural compounds have been demonstrated to have antimicrobial effect and the ability to restore the efficacy of conventional drugs. The objective of this work was to evaluate the antimicrobial effect of the hydroalcoholic extract of Curcuma longa L. (Cu) against H. pylori isolates.
Materials & Methods: The minimum bactericidal concentration of the extract was determined by means of the MTT assay; also, the combination and dose reduction indices for levofloxacin (LVX), metronidazole (MET), and rifampicin (RIF) antimicrobial agents were determined by checkerboard format. Interaction analysis was performed using the CompuSyn program.
Findings: About 90% of H. pylori isolates studied (9/10) were sensitive to the hydroalcoholic extract. Synergism was observed in more than 50% of Cu-LVX, Cu-MET, and Cu-RIF combinations. Additionally, for different concentrations of the extract, reduction rates in antimicrobial agents were determined to be between 0.5 and 360 times.
Conclusions: The hydroalcoholic extract of turmeric showed a good potential to be used as an antimicrobial agent in the treatment of H. pylori infection, either alone or in combination with antibiotics used, suggesting the renewal of the effectiveness of conventional antimicrobials in reducing the phenomenon of antimicrobial resistance.

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Aims: Essential oils are a complex of volatile compounds obtained from different parts of plants. Cinnamon (Cinnamomum zeylanicum) essential oil (EO) is known as a suitable source of antibacterial compounds. The aim of present study was to investigate the antibacterial activity of cinnamon EO and ZnO nanoparticles (NPs) against 2 strains of Listeria monocytogenes.
Materials & Methods: In this experimental study, 2 strains of L. monocytogenes (a standard strain and a fish isolated strain) were used. The antibacterial activity of cinnamon EO and ZnO NPs was assessed by well diffusion test. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of cinnamon EO and ZnO NPs were also determined using broth macrodilution method.  Moreover, the antibacterial properties of cinnamon EO and ZnO NPs were investigated in a liquid medium. The data were analyzed by SPSS 19 software, using one-way ANOVA and Tukey's post hoc tests.
Findings: The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of cinnamon EO were 16µl/ml and 64µl/ml, respectively. Furthermore, the MIC and MBC of ZnO NPs were 12.5mg/ml and 25mg/ml, respectively. The bacterial population significantly decreased with increasing the ZnO NPs and the cinnamon EO concentrations (p<0.05) and during cold storage, there were significant differences between the 2 strains.
Conclusion: Cinnamon essential oil and ZnO nanoparticles have strong antimicrobial effects against L. monocytogenes, so that the cinnamon essential oil shows bacteriostatic effects on Listeria, but ZnO nanoparticles show bactericidal effect.

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  Phenolic compounds, especially those of plants origin, are an essential part of the human diet, and are of considerable interest due to their antioxidant properties. The total phenolics content (TPC) and antioxidant and antimicrobial activities of pistachio green hull methanolic extracts of five different cultivars (Fandoghi, Kaleghochi, Ahmadaghai, Forotani and Seyed ali aghai) were studied. TPC ranged from 15.3 mg/g of GAE (cv. Kaleghochi) to 31.1 mg/g of GAE (cv. Ahmadaghai). The antioxidant capacity of extracts was assessed through DPPH and ABTS methods. A concentration-dependent antioxidative capacity was verified in both methods for all the cultivars. Antioxidant activity of Ahmadaghai cultivar in both methods was more than the other cultivars. The antimicrobial capacity was screened against Gram positive and Gram negative bacteria, and fungi. All the extracts inhibited the growth of Gram positive bacteria of Bacillus cereus and Staphylococcus aureus. Bacillus cereus was more susceptible than Staphylococcus aureus for all the extracts. The results obtained in this study showed that pistachio green hull can be used as a cheap and easily accessible source of natural bioactive compounds.

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In this research, antimicrobial activity of extract of Salvia leriifolia were investigated with different concentrations of the extract (5000, 10000, 15000 and 20000 mg/kg) on Staphylococcus aureus count and Total viable count in hamburger at different time intervals: after treatment (day 0) and after storage for 15, 30 and 45 day at -12^˚C, all microbiological analyses performed at 3 replication. The results showed that both of microbial total count and the number of Staphylococcus aureus in all samples with different concentrations of extract, decreased during storage. This decreasing effect was significant on day 15 and 30 for Staphylococcus aureus and total count, respectively. Our data also showed that the extract of Salvia leriifolia at highest concentration (20000 mg/kg) caused maximum reduction compared to other concentrations and extract at lowest concentration (5000 mg/kg) was less effective in initial Staphylococcus aureus population and microbial total count. These data indicate that Salvia leriifolia extract can exhibit antimicrobial activity against Staphylococcus aureus; so it can be considered as an alternative natural preservative in food products.