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A total of 200 samples of traditional ice creams were obtained randomly from the retail stores in the city of Shahr-e-kord. All the samples were analyzed for microbial contaminations according to the Iran national standard. Out of 200 samples, 100 showed mesophilic aerobic bacteria count more than 5*105 per gram of ice cream. One hundred fourteen samples showed Staphylococcus aureus count more than 102 per gram of ice cream. Ninety nine samples showed Enterobacteriacea count more than 102 per gram of ice cream. From 200 samples, 2 samples were Escherichia coli positive, and 24 samples showed Bacillus cereus count more than 103 per gram of ice cream. No Listeria monocytogenes was isolated from 200 samples.

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  Nowadays foods are preserved with using some methods to minimize contamination. One of these methods is food preservatives. Food preservatives with antagonistic effect usually interfere with cell membrane, enzyme action or genetic structure of microorganisms. In this investigation the effects of some preservatives were studied on the growth curve of Listeria monocytogenes that is isolated from dairy products. First the growth curve of bacteria was drawn when the preservatives were absent. Then the growth curve of bacteria was drawn when citric acid, which is a chemical preservative and nisin, which is a natural preservative, were present at sub-MIC concentrations. Next the growth curve of bacteria was drawn at the presence of both acetic acid and sodium citrate at different concentrations and in this period the changes of pH were measured. Listeria monocytogenes did not grow against citric acid at any sub-MIC concentrations which shows the sensitivity of bacteria to citric acid. Although this bacterium was sensitive to MIC concentrations of nisin, but it was significantly resistant to nisin after 18 hours. Also acetic acid and sodium citrate together can have more effect against this bacterium. This study showed that food isolated Listeria monocytogenes is resistant to sub-MIC concentrations of some preservatives, so it is suggested not to apply less concentration of MIC concentrations.

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Listeria spp. has been isolated from poultry, red meat and meat products and fish in many countries around the world. According to the reports of isolation of Literia monocytogenes in water and ice used for retaining freshness of food products and possibility of the increasing of bacterial contamination of poultry carcass after cooling in water chiller in poultry slaughter house, the effects of water chiller on Listeria monocytogenes contamination of poultry carcasses before and after chilling process in four industrial slaughter houses of western Azerbaijan province was investigated. Ninety poultry carcasses from 4 industrial slaughter houses in western Azerbaijan was investigated for Listeria monocytogenes before and after chilling process using the modified Canadian version of U.S. Food and Drug Administration (FDA) Listeria isolation method. Listeria monocytogenes contamination was 4.9 MPN g-1 in one sample before chilling process in water chiller. The result of Listeria monocytogenes contamination in the same positive sample and 6 other samples which did not show positive result before chilling process were 18, 43, 28, 21, 14, and 92, respectively. All of the isolated belongs to the serogroup 1. Paired-samples T test indicated significant difference (P<0.05) between the contamination levels before and after chilling process. Free available chlorine content of water in water chiller of these slaughter houses was not measurable.

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Listeria monocytogenes is a foodborne pathogen which has high resistance for unfavorable conditions. This pathogen is able to entering Viable but non culturable (VBNC) state in harsh conditions. The present study was aimed to consider the possibility of entering this pathogen in to VBNC state in heavy brine which used for produce brined fish. For this purpose L. monocytogenesat 1.12×10⁷ initial concentration as monitored in three treatments during 8 days: brine containing 30% salt (ES30), brine containing 10% salt (ES10) and starvation condition (DE).  For considering alive cells method of gene expression of 16S rRNAby RT-PCR was used. The obtained results showed that this pathogen in ES30 and DE treatments after three days enter in to VBNC state. According to obtained results ES10 treatment entering in to VBNC state on 5 days after inoculation. The results showed that there is the possibility of L. monocytogenes entering in to VBNC state, during brined and smoked fish or every other brined food product and defect of Standard detection methods. 

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  The aim of this study was to demonstrate the inhibitory capacity of two strains of  gram positive bacilli, isolated from intestinal content of Persian sturgeon, against Listeria monocytogenes growth. Two strains Lactobacillus casei AP 8 and Lactobacillus plantarum A P 12 , were screened for their antilisterial activity against.  L. monocytogenes, using a disk diffusion agar test. However, L. casei AP 8 always had the highest inhibitory effect. The spoiling potential and antilisterial capacity of bacterial strains was tested in sterile cold smoked roach (CSR) blocks inoculated with 10⁴ CFU g^− 1 of lactic bacteria and 10² CFU g^-1 of Listeria monocytogenes and then stored for 10 days at 4 °C followed by 30 days at 20 °C. L. casei AP8 grew a little faster L. plantarum A P 12 and none of them showed any adverse effect on quality of the product ( i.e. no total volatile basic nitrogen (TVBN) production and no acidification. Lactobacillus casei AP8 was the most efficient strain, maintaining the level of L. monocytogenes at <50 CFU/ g  during  40 dayss of storage at 4 and 20°C. In conclusion, biopreservation of cold smoked roach using bacterial cultures such as L. casei AP8  is a promising way to inhibit the growth of pathogenic bacteria such as L. monocytogenes with low effect on the product quality.

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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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Backgrounds: Listeria monocytogenes is an opportunistic pathogen causing listeriosis, its pathogenicity is due to the presence of virulence factors including InlA, InlB, PlcA, PlcB, ActA, Iap, and Hly. The purpose of this study was to evaluate the formation of biofilm and its association with serotypes and virulence factors in L. monocytogenes isolates.
Material and Methods: In this study, 51 L. monocytogenes isolates were collected from blood, urine, feces, placenta, rectum, and vagina samples as well as livestock and food samples. Biofilm production was measured using microtiter plate assay, and virulence genes were identified by PCR method.
Findings: Out of 51 isolates, 27 (52.9%) were non-biofilm producers, 17 (33.3%) were weak biofilm producers, four (7.8%) were medium biofilm producers, and three (5.9%) were strong biofilm producers. According to this study results, different L. monocytogenes strains could form biofilm with various intensities. The actA, flaA, inlJ, inlA, and plcB genes were observed in all the isolates. The frequency of the hlyA, plcA, iap, inlB, and inlC genes among the isolates was 90.2, 94.1, 98, 88.2, and 82.4%, respectively. There was no significant correlation between the presence/absence of virulence genes in biofilm producing and non-biofilm forming isolates, except for the inlC and iap genes, which showed a significant correlation with the ability to form biofilm.
Conclusion: Due to the high prevalence rate of biofilm formation among the isolates and the importance of biofilm production in medical surfaces and food industries, eradication of biofilm-forming isolates is important.
 

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The aim of this study was to develop a biopreservation strategy for cold-smoked Caspian  roach by the use of Lactobacillus casei previously selected for their capability to inhibit the growth of Listeria monocytogenes in this product.  An application on commercial smoked Caspian roach was tested by spraying L. casei (10⁴ CFU g^-1) on slices smoked Caspian roach. Microbial and chemical characteristics were each ten days compared to a control during forty days of storage. No significant differences were showed in microbiological and chemical characteristics of  inoculated slices with  L. casei. The strain L. casei  inoculated in SCR in a biopreservation goal exhibits some interesting properties: it is able to grow at high level without giving major quality changes in the product. In conclusion, biopreservation of SCR using lactic acid bacteria such as L. casei is a promising way to inhibit the growth of pathogenic bacteria such as L. monocytogenes with low effect on the quality of the product.

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Listeriosis, an infectious disease caused by eating contaminated food with the bacterium Listeria monocytogenes, has been recognized as an important public health problem. The disease affects primarily pregnant women, newborns and adults with weakened immune system. With the aim of using plants essential oil as natural antibacteria, the effect of Cumin (Cuminum cyminum) essential oil (in 0/02% and 0/04% concentration) was studied on Listeria monocytogenes in Iranian white cheese as a food model inoculated with 10³ cfu/ml in milk consumed for cheese making during 60 days storage period and compared with the blank sample which was not contained essential oil. According to results Listeria monocytogenes after 1 log reduction was not isolated from cheeses containing 0/02% and 0/04% Cumin essential oil after 30 and 15 days of storage time respectively. But in cheese without Cumin essential oil (0%), the bacterium was isolated during the period of study. Statistical analysis with Repeated Measures Define in SPSS 16 showed significant difference between all treatments (p<0.05). Also One-Way ANOVA showed that the difference of bacterial loads (Listeria monocytogenes) after 7th day of storage was statistically significant (p<0.05). These results showed that Cuminum cyminum essential oil has antibacterial effect on Listeria monocytogenes

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 New food products derived from by-products of dairy plants in the food industry is very important, Lorek is a product derived from whey, which in some regions of Iran, including Kurdisan and Azerbaijan provinces is produced. This product due to high amounts of nutritious ingredients and processes generate highly susceptible to contamination with pathogenic microorganisms. The purpose of this study was to evaluate the inhibitory effects monolaurin against pathogenic bacteria Staphylococcus aurous and Listeria monocytogenes in lorek. lorek produced from whey by heating at 95 °C and 6.5-6.7. Staphylococcus aurous and L. monocytogenes (1.5×10⁶ CFU/g) inoculate to lorek and same time monolaurin was also added in different concentration. This product was kept for three weeks at a temperature of 4 °C. Antibacterial activity against pathogenic bacteria was evaluated at the zero, 3, 7, 14 and 21 days using specific mediums. The results showed that monolaurin inhibit the growth of S. aureus and L. monocytogenes and its inhibitory effect on these bacteria is significant in comparison with a control group (P<0.05). The findings of this study was the most effective antimicrobial monolaurin against S. aureus, so that on days 14 and 21 in treatments containing 10000 and 20000 ppm  monolaurin, S. aureus was not isolated (P<0.05). Over time can be quite significant on Antimicrobial effect of monolaurin (P<0.05).

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Objective: Dendritic cells (DCs) play a critical role in the beginning and in the course of immune responses. By observing. Considering the defect in these cells in patients with tumor malignancy. In recent years there has been considerable interests in correction and use of these cells. In our prvious studies we showed that lysate of Listeria monocytogenese can induce maturation of dendritic cells, and induce TH1 response and increase the survival of tumor in an experimental model. The main objective in the present study is to evaluate the effects of different constituents of Listeria monocytogenes on DCs and their efficiency to induce TH1 response. Materials and Methods: After preparation of different components of Listeria monocytogenese (lysate of Listeria monocytogenes, protein and nucleic acid components), mouse bone marrow cells were cultured for 5 days in the presence of IL-4 and GM-CSF and treated with different components of Listeria for another 2 days. DCs were evaluated for the expression of Co-stimulatory molecules, MHC Class II molecules and Cytokine secretion. Results: The results showed that, all of the components are able to mature DCs efficiently and induce TH1 response. But dendritic cells matured with protein components shift the response to TH1 more efficiently. Conclusion: Our findings indicated that dendritic cell maturation protein components of Listeria monocytogenese shift the response to TH1 more efficiently and may have beneficial effects in cancer immunotherapy.

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Objective: Listeria monocytogenes is a facultative, gram-positive bacterium which is found in soil, water, decaying vegetables, raw milk, and contaminated dairies. Listeria monocytogenes causes listeriosis. Listeriosis is a zoonosis disease, which transfers from animals to humans by animal feces and contaminated dairies. Listeriosis causes the flu like disease or self-limited enteritis, but it leads to serious disease in elderlies, new-borns, pregnant women and immunocompromised persons. If pregnant women are infected by Listeria monocytogenes, the newborn probably will be miscarried, prematured or stillborn. For the importance of the bacteria on pregnant women’s and newborn’s health, there are so much concentration and studies on it. Culturing of the bacteria is so difficult and time-consuming and it needs at least 5 days to confirm. Our goal in this survey was to develop an PCR based molecular method for fast detection of the bacteria from the vaginal samples. Materials and Methods: In this survey 100 vaginal samples were examined. All of the samples were cultured and assayed with PCR method. Results: Among them, 7 samples for culture and 36 samples by PCR were positive for Listeria monocytogenes. Conclusion: In this study we showed that the PCR is a faster, more accurate and sensitive than culture method for the detection of Listeria monocytogenes in vaginal samples.

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Listeria monocytogenes is one of the most dangerous bacteria in food products which caused about 20 to 30% fatalities. One of the major foods which caused listeriosis is ready to eat (RTE). So, appropriate heating processing methods are need for elimination of L. monocytogenes. These bacteria has ability entering into viable but nonculturable (VBNC) form in unfavorable conditions. So this investigation was aimed to considering behavior of this pathogen at higher temperatures from recommended for elimination of these bacteria. For this purpose, bacteria in 5×10⁶ counts in mid log phase were inoculated into two medium BHI Broth and fish Broth (FB) and they exposed to 85 ºC for 10 minutes. Direct plate count on listeria choromogenic agar, BacLight^® Live/Dead and gene expression of 16S rRNA, the housekeeping gene, were done before and after heat shock. The results show that these bacteria lose their culturability during high heat shock. The results of fluorescent dyes showed the viability of these bacteria after heat shock (p< 0.01). The results of gene expression considering confirmed the results of fluorescence dyes and showed that 16S rRNA gene was expressed in nonculturable bacteria. According to these results, there is a big question on the D value on quality control for these bacteria in food processing processes, especially for RTE foods.

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Listeria monocytogenes is a foodborne bacterial pathogen causing Listeriosis. The aim of this study was to evaluate the effect of methyl cellulose edible coatings containing Carum copticum L. essential oil and turmeric (Curcuma longa L.) extract to control the growth of L. monocytogenes inoculated in chicken portions storaged at 4°C. For this purpose, chicken meat samples were coated with different concentrations of 0.3, 0.45 and 0.65% of essential oil and concentrations of 0.25 and 0.5% of turmeric extract. In the control group, sterile distilled water was used instead of the solution. The samples were coated by dipping method. All specimens were then stored in the refrigerator and counted for L. monocytogenes on days 0, 4 and 8. In the present study, the minimum inhibitory concentration (MIC) of Carum copticum essential oil was 0.064%. The results of this study showed that there is a significant difference between L. monocytogenes population in coated and non-coated chicken samples (p<0.001). Statistical analysis showed that the mean log of the number of bacteria in all groups from day 1 to 8 showed a decreasing trend. In total, according to the results, it can be concluded that methyl cellulose coating containing Carum copticum EO with turmeric extract can be used to control the growth of L. monocytogenes in chicken meat.

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The aim of this study was to investigate the antimicrobial and antioxidant effects of chitosan edible film containing nanoemulsion of Melissa officinalis L. extract and Bunium persicum essential oil on Listeria monocytogenes inoculated into camel meat. The studied films were prepared using 2% chitosan and 2.5% and 5% of nanoemulsion of Bunium persicum essential oil and 4% of Melissa officinalis L. extract. The antimicrobial and antioxidant effects of coated camel meat during 16 days of storage at 4 °C with a 4-day interval (0, 4, 8, 12, 16) were evaluated. The coated portions were chemically evaluated. Most of the essential oil compounds include: cuminaldehyde (24.37%), γ-Terpinene (19.99%), and P-cymene (9.71%). The MIC of Melissa officinalis L. extract and Bunium persicum essential oil against L. monocytogenes were 1% and 0.25%, respectively. The antioxidant effects of films by DPPH method showed that the addition of essential oils and extracts increases the antioxidant properties of films. The antimicrobial effect of films by disk diffusion method, the largest diameter of growth inhibition zone (17.15 ± 0.16) was related to chitosan film containing 5% Bunium persicum essential oil and 4% Melissa officinalis L. extract. The average count of L. monocytogenes in the control treatment was higher than the other treatments. The results of TBARS showed that the antioxidant properties of films containing Bunium persicum essential oil and Melissa officinalis L. extract was higher than the control sample. The pH level in the samples coated with chitosan film containing 5% Bunium persicum essential oil and 4% Melissa officinalis L. extract was lower than the other treatments. In general, the prepared films have good antimicrobial and antioxidant properties against L. monocytogenes, which increase with the addition of plant compounds.