هادی کوهساری

Kefir beverage is one of the oldest fermented milk products, which is a natural probiotic and a complex of microbial symbiotic that is obtained from the fermentation of milk by kefir grains. The study aimed antibacterial activity of kefir samples prepared with cow milk against 10 pathogenic bacteria. Kefir grains were added to cow milk (Full-fat and low-fat) and fermentation was done at 25°C and 37°C. Grains were separated from kefir extract and the antibacterial activity of kefir extract was evaluated against 10 pathogenic bacteria by well method. Kefir samples prepared at 37°C compared to 25°C samples showed more antibacterial activity against S. aureus, P. aeruginosa and native K. pneumoniae isolated. The most antibacterial activity of kefir samples against E. faecalis and S. dysenteriae was related to the samples prepared with low-fat milk at 37°C, respectively, with the average diameter of inhibition zone of 18.5 and 12.5 mm. The samples prepared with full-fat milk in 25°C and 37°C indicated more antibacterial activity with the diameter of inhibition zone of 22 and 19 mm against the standard K. pneumoniae strain, respectively. Significant difference was not observed about milk type and fermentation temperature effect on antibacterial activity against E. coli, both native isolate and standard strain and S. typhimurium (P<0.05). B. cereus showed significant resistance to kefir samples. Kefir prepared with cow milk is recommended due to significant antibacterial activity.

Kefir is a complex probiotic, and a microbial symbiosis collection that is prepared from milk fermentation by kefir grains. The type of substrate (milk) used to prepare this fermented beverage is effective on its biological activities, including its antibacterial activity. The purpose of this study is to investigate the antibacterial activity of kefir samples prepared with cow, buffalo, ewe and goat milk. Activated kefir grains were added to cow (Full-fat and lowfat), buffalo, ewe, and goat milk, and the fermentation process was performed at 25°C and 37°C. After the fermentation process, kefir grains were separated from kefir extract and the antibacterial activity of the extract against 10 pathogenic bacteria was evaluated based on agar diffusion and by the well method. The type of milk used in the preparation of kefir samples at 25°C and 37°C had a significant effect on antibacterial activity against all tested bacteria except S. typhimurium (P<0.05). Kefir samples prepared at 37°C compared to kefir samples prepared at 25°C showed more antibacterial activity. The highest antibacterial activity against the P. aeruginosa, E. faecalis, K. pneumoniae native isolate and B. cereus in the samples prepared with buffalo milk and at the fermentation temperature of 37°C, respectively, with the mean of diameter of inhibition zone of 22, 24.5, 20 and 18 mm was observed. The highest antibacterial activity against S. dysenteriae, S. aureus and S. typhimurium is related to kefir samples prepared with goat's milk and at fermentation temperature of 37°C. The highest antibacterial activity against the standard strain of E. coli, B. cereus, and S. aureus was observed in kefir samples prepared with ewe milk at 37°C. The most sensitive bacteria studied to the samples prepared with full-fat cow's milk were E. coli native isolate and K. pneumoniae standard strain. In the final conclusion considering the antibacterial activity of kefir samples prepared with buffalo, goat and ewe milk, it is recommended to use the milk of these animals as a suitable substrate and substitute for cow's milk to prepare this fermented beverage. Also, it is suggested to perform the fermentation process at 37°C to achieve more antibacterial activity.

Probiotics are live microorganisms that have beneficial effects on human health when consumed in sufficient quantities (Fuller 1989). Kefir beverage is a natural complex probiotic and one of the oldest fermented milk products. This microbial symbiotic is obtained by fermenting milk with kefir grains. Consumption of kefir is effective in promoting health and increases the body's immune system, balances blood pressure, treats digestive diseases and reduces serum cholesterol levels, and also has antibacterial, antifungal and antitumor activities (Farnworth 2005). The microflora of kefir grains contains a group of specific microbes that exist in a complex symbiotic relationship, including species of yeasts, lactic acid bacteria (Lactobacillus and Lactococcus), and acetic acid bacteria (Garbers 2004). Kefir is a complex probiotic, from a microbial symbiotic that is obtained from milk fermentation by kefir grains, and its consumption is effective in promoting health. The main raw material for making kefir beverage is cow's milk. For various reasons, some people do not consume cow's (animal) milk: they may be vegetarians or have health problems such as lactose intolerance or a casein allergy (Bau et al., 2015). The purpose of this study is to investigate the antibacterial activity of kefir samples prepared with soy milk against 10 pathogenic bacteria.

The regeneration and fermentation process of grains was done with successive subcultures in milk according to the method presented by Ajam and Koohsari (2020). Activated kefir grains were added to soy milk (with 2% and without sucrose) and the fermentation process was performed at 25°C and 37°C. After fermentation, kefir grains were separated from kefir extract and the antibacterial activity of kefir extract against 10 pathogenic bacteria including Staphylococcus aureus, Bacillus cereus, Shigella dysenteriae, Enterococcus faecalis, Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli (native isolate and standard strain) and Klebsiella pneumoniae (native isolate and standard strain), was evaluated based on diffusion in agar and by the well method. For this purpose, the method presented by Weinstein et al., 2018 was used. Regarding sensory tests, in order to compare with kefir samples prepared from soy milk, kefir samples with cow's milk were also prepared, so that a comparison can be made between these samples. In order to study this comparison, indicators of overall appearance, color, fragrance, taste and mouthfeel and total score were measured.

The results of the effect of fermentation temperature (25°C and 37°C) and the presence of sucrose in kefir samples prepared with soy milk on the antibacterial activity against the tested bacteria, except for the gram-positive bacteria E. faecalis and S. aureus, indicate a significant difference between treatments (P>0.05). The presence of sucrose and fermentation temperature had a significant effect on antibacterial activity against all tested bacteria except E. faecalis and S. aureus. And kefir samples prepared with soy milk containing sucrose showed more antibacterial activity. The highest antibacterial activity of kefir samples prepared with soy milk against P. aeruginosa was related to kefir samples prepared with soy milk containing sucrose at fermentation temperatures of 25°C and 37°C with mean of diameter of inhibition zone of 20 mm. The highest antibacterial activity of the kefir samples prepared with soy milk against E. faecalis is related to the samples prepared with soy milk without sucrose and at the fermentation temperature of 25°C with mean of diameter of inhibition zone of 18.5 mm and the highest antibacterial activity of the samples against S. aureus was related to the samples of soy milk without sucrose at the fermentation temperature of 37°C with mean of diameter of inhibition zone of 16 mm. The highest antibacterial activity against S. dysenteriae and S. typhimurium was observed in kefir samples prepared with soy milk containing sucrose at fermentation temperatures of 25°C and 37°C. The highest antibacterial activity of kefir samples prepared with soy milk against the native isolate and standard strain of K. pneumoniae was related to kefir samples prepared with soy milk containing sucrose at fermentation temperatures of 37 with mean of diameter of inhibition zone of 21 and 18 mm, respectively. Compared to other tested bacteria, E. coli and especially the standard strain of this bacteria, showed more resistance than kefir samples prepared with kefir soy milk. In this regard, B. cereus showed resistance to all treatments and no antibacterial activity was seen against this spore bearing bacteria bacterium. Based on the results of sensory tests, no significant difference was observed between the treatments in any of the indicators (P<0.05), but nevertheless, the sensory evaluations indicated low sensory acceptability of kefir samples prepared with soy milk, so compared to kefir samples obtained from cow's milk, it obtained a lower overall score. Antibacterial activity of fermented beverage is related to the compounds present in this beverage. It has also been reported that the compounds in kefir drink are affected by the type of substrate or milk (soy milk in the present study), fermentation conditions, kefir grain origin and storage conditions (Rosa et al., 2017). Soy milk has different carbohydrates, the most important of which are sucrose, raffinose and stachyose, while lactose is the main carbohydrate in cow's milk (Pinthong et al., 1980). Among the mechanisms of antibacterial activity of kefir extracts, we can mention acidic pH, as a result of lactose fermentation or alternative substrates, increasing the content of organic acids, such as lactic acid, acetic acid, etc., by microorganisms in kefir grains (Kourkoutas et al., 2007). Addition of carbohydrates (including sucrose) improves the ability of kefir grain microorganisms to produce lactic acid in soy milk. In addition to the role of organic acids, the antimicrobial activity of kefir beverage is related to the production of peptides (bacteriocins), carbon dioxide, hydrogen peroxide, ethanol and diacetyl (Oliveira Leite et al., 2013). In addition to these compounds, the exopolysaccharide produced by kefir grains called kefiran also has antibacterial activities (Wang et al., 2008 and Prado et al., 2015).

The results indicated significant antibacterial activity of kefir samples prepared with soy milk against the tested bacteria except for B. cereus and the standard strain of E. coli. The remarkable effect of kefir samples prepared with soy milk against Gram-negative bacteria such as P. aeruginosa, K. pneumoniae, both native isolates and standard strains, and S. dysenteriae was very interesting.

The composition and biological activities of kombucha beverage depends on type of herbal tea, concentration of sucrose and the fermentation time. This study aimed to investigate the effect of different preparation conditions on antibacterial activity of heated kombucha beverages by Response Surface Methodology (RSM). Four types of herbal teas, including black tea, green tea, lemon verbena and peppermint were prepared with three concentrations of sucrose (2, 5 and 8%) and inoculated with active kombucha culture. After 7, 14 and 21 days, beverages were heated by autoclaving and their antibacterial activity against four bacteria including Escherichia coli, Shigella dysenteriae, Staphylococcus aureus and Bacillus cereus was evaluated by well method. The RSM was used to investigate the effect of sucrose concentration, fermentation time and type of herbal tea on antibacterial activity of heated beverages. Increasing sucrose concentration had significant effect (P<0.0001) on antibacterial activity of heated beverages against all tested bacteria. Increasing of fermentation time had significant effect (P< 0.0001) on antibacterial activity of heated beverages against E. coli and S. dysenteriae. Type of herbal tea had significant effect on antibacterial activity against S. aureus and S. dysenteriae. The highest antibacterial activity against E. coli and S. dysenteriae was observed in beverages prepared with lemon verbena. Beverages prepared with green tea showed highest antibacterial activity against S. aureus. The highest antibacterial activity against B. cereus was observed in heated beverages prepared with black tea and peppermint. In general, the results showed significant antibacterial activity of heated kombucha beverages against the tested bacteria.

Lactic acid bacteria which are found in large amounts in dairy products, have antagonistic activity against many pathogenic microorganisms. In this study, the inhibitory effect of Lactobacillus strains isolated from buffalo milk and yogurt in Bandar Gaz city was investigated. Raw milk and yogurt samples were cultivated on MRS medium, incubating anaerobically at 37°C for 48 h. The suspected colonies were identified on the basis of Gram’s staining and biochemical tests. The antibacterial activity of the cell-free supernatant extracted from Lactobacillus strains was determined using the agar well diffusion method against standard strains including Shigella flexneri ATCC 12022 ، Salmonella typhimurium ATCC 14028 ، Vibrio paraheamolyticus ATCC 17802 ، Escherichia coli ATCC 11303 and Staphylococcus aureus ATCC 29213. A total 10 Lactobacillus strains were identified as L. plantarum, L. casei, L. acidophilus. The cell-free supernatant of L. plantarum A1 had a relatively strong inhibitory effect against S. aureus and a moderate inhibitory effect against E. coli and S. flexneri, while no inhibitory effect on V. paraheamolyticus and S. typhimurium growth. L. casei B1 showed a moderate inhibitory effect against S. flexneri and S. aureus. The supernatant of L. acidophilus R1 vs. S. aureus showed a moderate inhibitory effect and had an inhibitory effect on V. paraheamolyticus. The results of this study showed that Lactobacilli isolates had good inhibitory activity against some food pathogens, therefore further studies on their use as biopreservatives to prevent the survival and proliferation of microorganisms in food products are recommended.

The importance of herbal and spice essential oils is that in addition to creating flavor in foods, their main active ingredient has antimicrobial effects, for this reason, consumers prefer herbal oils to chemicals. The Lamiaceae are a family of flowering plants commonly known as the mint family. Many members of this family are aromatic herbs and are widely used as spices in the food industry. Mentha (also known as mint) is a genus of plants in the family Lamiaceae . The species that makes up the genus Mentha are widely distributed and can be found in many environments. Most grow best in wet environments and moist soils. The genus Mentha consists of over 20-30 species that grow widely throughout the world. Members of this genus are one of the most important plants producing essential oils. There are many varieties of essential oils in different species (Zargari, 1995). Mentha aquatica L. that known in the northern regions of Iran locally called Ojji, is a commonly spice herb has used. This plant grows in aquatic places throughout Iran, especially in northern Iran. One of the main habitats of this plant in Iran is Mazandaran province in northern Iran (Getahun et al., 2008). Food poisoning caused by Escherichia coli and Staphylococcus aureus are known as the most important causes of food poisoning. This study was caried out to evaluate the chemical composition and antibacterial activity of essential oil of Mentha aquatica L. against S. aureus and E. coli Plant of Ojji (Mentha aquatic) was obtained from from local market in Sari township located in Mazandaran Province in northern Iran and was approved by the botany laboratory of Islamic Azad University, Gorgan branch. The essential oil of herb leafs was extracted by hydrodistillation method and Clevenger apparatus. Gas chromatography–mass spectrometry (GC-MS) was used to identify essential oil chemical compounds. The gas chromatograph used was Agilent 6890 with a capillary column of 30 m in length and an internal diameter of 250 μm and a layer thickness of 0.25 μm HP-5MS. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the essential oil of this plant oil were determined using micro-dilution broth method or turbidimetric assay. The Bacterial strains used in this study were two species of Escherichia coli PTCC 1338 and Staphylococcus aureus PTCC 1112. The bacteria were provided in lyophilized form from Biotechnology Institute in Iranian Research Organization for Sciences and Technology, Tehran. Different dilutions of essential oil in Mueller Hinton Broth were exposed with bacterial suspension of 5 ×105CFU/ml of each of the bacteria tested for 24 hours at 37 ° C. After this time the results were recorded as microbial turbidity of visible. The last dilution (lowest concentration) in which microbial turbidity was not observed, as the minimum inhibitory concentration (MIC) was considered. For the determination of MBC, from the tube that contained essential oil concentrations higher than the MIC were cultured onto the Nutrient agar medium. The MBC was defined as the lowest concentration that allowed no visible growth on the agar (Cockerill et al., 2012). The results of the gas chromatography analysis were determined 27 chemical compounds that formed more than 98% of the essential oil compounds. 3-Carene were the highest concentrations chemical compound of Mentha aquatica essential oil with 61.24%. Cineol, Limonen and Agarospirol were other known compounds of the essential oil of this plant that were measured in quantities of 9.4%, 6.81% and 4.78%, respectively. 3-Carene is a hydrocarbon monoterpene. Therefore, the antibacterial activity of the essential oil of Mentha aquatica can be attributed to the presence of hydrocarbon monoterpens. Identification of the chemical constituents of the essential oil of Mentha aquatica in different parts of the world indicates different reports of the presence of different compounds in this essential oil. Different findings may be due to intrinsic properties of essential oils such as pre-harvest factors such as variety, environmental conditions, ecological factors and differences in extraction methods. Although production of secondary metabolites in plants are made by genetic processes, they are affected by environmental factors. The results of antibacterial tests indicated that S. aureus was more sensitive than E. coli to the essential oil of this plant as MIC and MBC of essential oil of this herb on the S. aureus 1.56 and 1.56 mg/ml and on the E.coli was 3.12 and 6.25 mg/ml respectively. The cause of the lower sensitivity of gram-negative bacteria may be due to the presence of an outer membrane in gram-negative bacteria that restricts the release of hydrophobic components of the essential oil into the lipopolysaccharide layer. One of the important properties of the essential oils is their hydrophobic properties, which distribute them in lipid portions of the cell wall, altering and destroying their structure and increasing their permeability. As a result, much of the ions and other vital contents of the cell leak out, eventually leading to bacterial death. Concerning the antibacterial activity of the essential oils, it has been suggested that phenolic metabolites in plants such as Mentha aquatica are capable of releasing a hydrogen from the hydroxyl group present in their aromatic ring and causing the oxidation of free radicals in lipids and other cellular membrane biomolecules and its destruction and thus produce their antioxidant, antimicrobial and anti-inflammatory properties. The antibacterial activity of essential oil of Mentha aquatica can be attributed to the presence hydrocarbon monoterpene compounds such as 3-Carene along with compounds such as Cineol, Limonen, Agarospirol, Eucalyptol and Menthone that leads the potential for its use as a natural preservative in food.

Kefir is produced from the fermentation of milk by microorganisms in kefir grains. Kefir grains include lactic acid bacteria, yeast, and acetic acid bacteria surrounded by a protein matrix and polysaccharide called kefiran. One of the most important antibacterial compounds of this beverage is microbial exopolysaccharide of kefiran. The present study aimed to investigate the effect of milk type, fermentation time, temperature, and stirring conditions on the production of kefiran by kefir grains. Activated kefir grains were added to full-fat and non-fat milk. Fermentation was carried out at 25 and 37 °C under stirred and non-stirred. After 24, 48, 72, and 120 h of fermentation, the grains were separated from kefir extract and kefiran exopolysaccharide was extracted from kefir grains. The effect of these variables and their interaction on the production of kefiran using Design-Expert software and full factorial design have been analyzed. Also, the MIC and MBC of extracted kefiran were determined against Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Shigella dysenteriae. All fermentation conditions and their interactions had a significant effect on kefiran production. Considering all fermentation conditions and interaction of all factors, more kefiran were produced in fermented kefir grains at 37 °C compared to 25 °C, in full-fat milk compared to non-fat milk, under stirred conditions compared to non-stirred and fermented beverages for 48 and 120 h. MIC and MBC of extracted kefiran for tested bacteria were determined in the range of 1.4-11.25 mg/mL.

Aspergillus flavus is one of the important species of molds that can produce toxins during improper storage of wheat grains. In this study, different amounts of calcium oxide (0, 0.5, and 1%) were mixed with wheat samples containing mold spores. After 20 days, the samples were exposed to gamma radiation (0, 5, 10, 15, and 20 KGy). The presence of A. flavus, Aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2) was assessed in samples. The results indicated that the effects of calcium oxide, gamma irradiation, and their interactions were significant on A. flavus, AFB1, and AFB2 contamination. Furthermore, other toxins like AFG1 and AFG2 were not found in the samples. An additional reduction in AFB1 and AFB2 was observed when irradiation was accompanied by Cao, and the maximum inhibition of aflatoxin production was achieved at 0.5% CaO. Consequently, based on the standard maximum limit of 10 KGy for cereals, the findings of this research suggest that 0.5% of calcium oxide and 10 KGy of irradiation could be applied in the storage of wheat grains to mitigate A. flavus, AFB1, and AFB2.

Propolis is one of the most important bee byproducts that, due to its high antimicrobial properties, has the potential to be used as a food additive. This study investigated the effects of aqueous and ethanolic extracts of propolis on the microbial load of raw milk.

Raw milk samples containing0.1, 0.5, 1, and 2% ethanolic extracts and 0.5, 1, 3, and 5% aqueous extracts were prepared. The treatments were incubated at 4 °C and 25 °C and were cultivated by pour-plate technique in PCA medium during storage times of 0, 2, 24, 48, and 72 hours. By a total count of microorganisms, the effects of different concentrations of propolis extracts on the microbial load of raw milk were investigated. The chemical compounds of the extracts were identified by gas chromatography–mass spectroscopy (GC-MS) analysis.

At 25 °C, all concentrations of aqueous and ethanolic extracts affected the microbial load of raw milk, but at low concentrations, such effects were observed after 24 hours. Aqueous and ethanolic extracts of propolis at 25 °C compared to 4 °C in lower concentrations showed more antimicrobial activity. It was also found that propolisextracts need time to exhibit high antimicrobial activity. Forty-onecompounds were identified with the dominance of phenolic and flavonoid compounds. Discussion and

The antimicrobial properties of the tested propolis extracts can be attributed to the high amounts of phenolic and flavonoid compounds and the use of this bee product as an additive is recommended.

Probiotics are living microorganisms that provide beneficial effects when they are eaten with food. The probiotic dairy products raise the risks associated with increased cholesterol and lactose intolerance. In this research, fruit and vegetable juices of apple, banana, carrot and tomato were used as substrates for producing probiotic beverages and the viability of two LABs of L. acidophilus and L. plantarum in these products was investigated. Fruit and vegetable juices were inoculated with bacterial suspensions to obtain a concentration of 105 CFU/ml for each LAB. Samples were incubated at 37°C for 72 hours and at 24-hour intervals, pH levels and viable cell count in products were determined based on CFU/ml. Fermented products were transferred to the refrigerator and the viability of LABs was determined at 4°C for 4 weeks. The results show that, in all products, the pH decreased over time, so that there was a significant difference between the two examined bacteria during the experiment (P<0.05). Both LABs were able to grow well in products and to ferment the fruit and vegetable juices properly implying that all the beverages were able to provide suitable conditions for the growth of two strains of LABs. L. plantarum showed a higher viability in cold storage at 4°C. In general, considering the high growth rate of these bacteria in the products and pH reduction and their viability during cold storage at 4°C, fruit and vegetable juices of apple, banana, carrot and tomato can be a good substrate for producing non-dairy probiotic beverages.

An 8-week experiment was conducted to evaluate the effect of different carbon sources and protein levels on mucus immune parameters, hepatic enzymes and intestine lactic acid bacteria loading in biofloc system of common carp (Cyprinus carpio) juvenile in intensive culture. Fish fed the feed containing 20 or 30% crude protein including two groups in clear water conditions with no biofloc, two biofloc groups given a molasses as additional carbon source (M), two biofloc groups given rice bran (RB) and two biofloc groups given mixture of molasses + rice bran at equal weight ratio (M+RB). At the end of trial, mucus immune parameters (lysozyme activity and total immunoglobulin), hepatic enzymes (LDH, AST, ALT, ALP) and intestine lactic acid bacteria loading were investigated. The results showed that significant improvements in immune parameters were observed in fish fed 30% dietary protein and reared in biofloc condition (P<0.05). Hepatic enzymes and lactic acid bacteria loading significantly improved in fish fed 30% dietary protein and reared in M and M+RB biofloc than control group (P<0.05). In conclusion, using mixture of M+RB as carbon source associated higher protein can be improved immune response, metabolic enzyme and lactobacillus loading in intensive farming of common carp.

Aspergillus flavus is one of the hazardous fungi which appear in poor storage conditions. This mold produces dangerous toxins of aflatoxins in corn grains. Hence the investigation of reduction possibility of its growth and toxins is important. In this research the effects of calcium oxide (0, %0.5 and %1) and gamma ray (0, 5, 10, 15 and 20 KGy) on growth of Aspergillus flavus and levels of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1 and aflatoxin G2 (AFG2) were investigated. Analysis of variance showed significant effects of irradiation (P<0.0001), calcium oxide (P<0.001) and their interactions (P<0.0001). Aspergillus flavus and AFB1 and AFB2 toxins decreased with increasing irradiation. Further reduction of AFB1 and AFB2 toxins was observed during accompaniment of 0.5% calcium oxide with irradiation. However, simultaneous application of 1% calcium oxide with radiation prevented and reduced more Aspergillus flavus. AFG1 and AFG2 toxins were not detected in any of the samples. Consequently, with considering 10 KGy standard food irradiation limits, it is recommended that 0.5% calcium oxide concentration before storage and irradiation intensity of 10 KGy after storage were applied for corn grains to control mold growth and production of aflatoxin toxins.

Isolation and identification of lactic acid bacteria from local products can play an important role in the introduction of unique types of probiotics. The present study was conducted in an attempt to isolate lactic acid bacteria from local dairy produced in the township of Gorgan which had the ability to inhibit the growth of some gastrointestinal pathogens. In order to isolate lactic acid bacteria, cheeses samples were sub-cultured on media cultures of MRS agar, M17 Agar , KAA and MRS+Vancomycin. Then, isolates were identified based on general morphological characteristics, biochemical and sugar fermentation tests. Using agar well diffusion, the antibacterial activity of culture supernatant of lactic acid bacteria was tested against four pathogenic bacteria. Among 24 samples of local cheeses and dooghs and 4 industrial samples, a total of 73 isolates were identified in which Lactobacillus casei was the most frequent isolate with with 34.24%. Lactobacillus casei and Lactobacillus acidophilus isolated from sheep's dough and sheep's cheese and Lactobacillus delbrucki and Lactobacillus ramenosus isolated from sheep's dough showed significant antibacterial activity against all pathogenic bacteria studied, namely, E. coli, S. aureus, B. cereus and C. freundii. Moreover, lactic acid bacteria isolated from industrial samples showed less antibacterial activity compared to isolates of local samples. Overall according to antagonistic effects of lactic acid bacteria isolated from of Gorgan’s local dairy products, it is recommended to evaluate their use as probiotic bacteria.

Staphylococcus aureus is an opportunistic pathogen and one of the most important health-threatening agents worldwide. Expression of bacterial virulence factors is not similar in laboratory medium conditions and in vivo. The aim of the present study was to evaluate the effects of adding 5% calf serum on the virulence genes expression of S. aureus.   The expression levels of agrA, RNAIII, hla, spa, and mecA genes were     determined during the growth of S. aureus isolates in BHI broth and BHI broth enriching with calf serum during different growth phases. Therefore, the growth curve of the five isolates of S. aureus in two different culture conditions was plotted. Subsequently, RNA was extracted from different phases of growth and the genes expression were analyzed by Real-time PCR.   In average, the expression levels of agrA and RNAIII from stationary phase to the exponential phase in BHI broth containing calf serum was increased 3.4 and 9.5-fold, respectively, while the agr system could not appropriately play its regulatory role in the expression of virulence genes. As a result, the expression of hla gene was decreased 0.81-fold and the expression levels of spa and mecA genes was only increased 1.25 and 1.03-fold, respectively.   Regardless of the growth phase, the expression of the whole genes in BHI broth containing calf serum were increased in comparison to BHI broth. Consequently, it appears that S. aureus is capable to induce virulence genes expression in the presence of calf serum factors similar to conditions available in vivo.

Propolis is one of the byproducts of bees. Biological activities of propolis is related to geographical and botanical origion. The aim of this study was to evaluate the antibacterial and antioxidant activity the three types of propolis with different geographical origion from Golestan province in northern Iran.The evaluation of antibacterial activity by using agar well diffusion method was performed. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of propolis samples were determined by using broth macrodilution tube method. Also the total phenolic content (TPC), total flavonoid content (TPC) and free radical scavenging activity of propolis samples were determined. Grampositive bacteria compared to gram-negative bacteria showed more sensivity to different concentrations of propolis samples. As MIC of propolis collected from the geographic region of the Shast Kola for B. cereus and S. aureus was, 0/048 and 0/19 mg/ml respectively and for S. dysentery and E.coli 3.12 and 3.12 mg/ml respectively. Propolis sample of JahanNama area with mean of 142.67 mgGAE/g sample and 35.24 mgQE/g sample showed highest TPC and TFC. The highest DPPH radical scavenging activity was related to Shast Kola propolis sample. The antibacterial activity of propolis samples had direct correlation with phenolic
and flavonoid content. The total phenolic and flavonoid content had negative correlation with free radical scavenging DPPH, explain that the antioxidant activity of propolis also is related to other components. So the identification of other compounds of propolis is recommended.

Study in order to introduce new antimicrobial agents with natural origin to prevent the antibiotic resistance and eliminating its effects, employing chemical agents is an indispensable necessity. Honey, as an important food with natural origin has high antimicrobial potential. Several factors have contributed to the antibacterial activity of honey. For example, acidity, osmolarity, hydrogen peroxide, phenolic and flavonoid compounds, including these factors. Also, small amounts of glucose oxidase, protease, amylase, catalase and phosphatase enzymes and chemical compounds such as methylglyoxal are also effective. Floral origin of honey is effective on its biological properties including antimicrobial, anti-tumor, anti-inflammatory, antioxidant and antiviral activity. So this study was done to evaluate the antibacterial activity and physico-chemical analysis of four types of honey with different floral origin including: Thyme, Eryngium, Pennyroyal and Dill collected from the bee hives in Golestan province.
Four honey samples with different floral origin including, Thyme, Eryngium, Pennyroyal and Dill were collected from the bee hive in the Golestan province in north of Iran. The bacterial strains used in this study, including two species of gram-negative of Escherichia coli and Shigella dysenteriae and the two species of gram-positive of Staphylococcus aureus and Bacillus cereus were provided in lyophilized. Bacterial strains in BHI broth were activated and from each of them were prepared bacterial suspensions equivalent to the McFarland 0.5 turbidity standard (1.5×108 CFU/ml). Evaluation of antibacterial activity using agar well diffusion method was performed. For this purpose serial dilutions of honey samples were prepared aseptically in sterilized distilled water. Surface of Mueller Hinton agar were uniformly inoculated with bacterial suspension containing of 1.5×108 CFU/ml. Then wells of 8 mm in diameter were prepared and these wells were filled with different dilutions of honey samples. After incubation at 37°C for 24 h, antibacterial activity was analyzed by measuring the zones of inhibition. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of honey samples were determined by using broth macro-dilution method. For this purpose, each of the tubes from different dilutions of honey samples were added by 5×105 CFU/ml from each of the tested bacteria and incubated for 24 h at 37°C. The results for microbial turbidity of visible were recorded. The last dilution (lowest concentration) in which microbial turbidity was not observed, as the MIC was considered. For the determination of MBC, from the tube that contained honey concentrations higher than the MIC were cultured onto the agar medium. The MBC was defined as the lowest concentration that allowed no visible growth on the agar. Also the studied physico-chemical properties were moisture content, pH, acidity, ash content and reducing sugars that was performed according to the Iranian National Standard No. 92.
The results indicated that the antibacterial effects of the tested honeys, and the difference between floral origins honeys is effective in antibacterial properties. MIC and MBC values obtained for the tested honeys were in the range of %6.25-50% (vol/vol). Highest antibacterial activity was recorded for Eryngium honey by agar well diffusion method with zone of inhibition of 15.5, 14,11 and 11 mm against S. dysenteriae, S. aureus, B. cereus and E. coli at concentration of 50% v/v respectively and its MIC for this bacteria were, 6.25%, 10%, 10% and 25% respectively. also low antibacterial activity of Pennyroyal honey was confirmed so that MIC of the this honey for E. coli, S. aureus, B. cereus and S.dysenteriae was, 50%, 25%, 12.5% and 10%, respectively. The quality of honey depends on a number of physico-chemical properties such as moisture, ash content, pH, acidity, the amount of sugars. For this reason, standards for honey have been set by different countries. The physico-chemical analysis of honeys showed moisture contents in the range of 22.56-25.36%, acidity in the range of 12.58-13.59 meq/kg, pH in the range of 4.15-4.26, reducing sugars in the range of 63.7-63.8%. Also the ash content of Eryngium honey with 0.183% was higher than the other honey samples. This higher level might be due to the higher pollen count in this region. High ash contents may also depend upon the floral origin of honey and the material collected by bees during foraging. The low acidity of honey samples studied in the present study was due to the fact that there was no unwanted fermentation in these samples. Overall, the results implied that honey samples with different floral origin collected from the bee hive in the Golestan province in north of Iran have variable potential antibacterial activity. The variety of antibacterial effects of different types of honey can be due to differences in plants that honey is obtained from. In other words, different species of plants in different regions have different compounds and their obtained honey will not be the similar and thus its biological effects also will be different.

Mentha spicata L. (Peppermint) is a widely used medicinal herb that also as a commonly herb spice has used in the food industry.This study carried out to evaluating of chemical composition and antibacterial activity of the essential oil of Mentha spicata L. (Peppermint) against Staphylococcus aureus and Escherichia coli.Essential oil of the herb leafs was extracted by Clevenger apparatus. Chemical composition of essential oil was identified with a Gas chromatography/mass spectrometry system and then Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of this essential oil were determined using micro-dilution broth method in microplate 96 pits. A total of 33 chemical constituents were identified which contained 98.5% the total of essential oil compounds. The most important components of this essential oil were: carvone (%28.35), menthol (%14.35), methylene (%14.059) and limonene (%9.303). MIC and MBC of essential oil of this herb against the S. aureus 25 and 25 µg/ml and against the E.coli was 50 and 100 µg/ml respectively. Due to antibacterial compounds of essential oil of this plant, it can be used as a natural preservative in food.

Unpasteurized as traditional ice cream production in Iran is very common due to the increasing use of herbal compounds as inhibitors of microbial growth, this study to examine the antibacterial effects of Lemon juice against Staphylococcus aureus and Escherichia coli in Ice cream prepared in the laboratory.In order to , ice creams containing concentrations of 1,2, 5,10% lemon juice was prepared .The samples were inoculated with bacterial suspension containing 105 cfu/gr . Samples with control samples were stored in the freezer - 20 and during the time of 1, 2, 3, 7, 14 and 21 days antibacterial effects of various concentrations of lemon juice was evaluated by culture-specific .The results showed that in all concentrations, significant difference was observed between the number of bacteria with the control group(P

This study was carried out to evaluate the phytochemical, antioxidant and antibacterial activity of Hypericum perforatum L., the aerial parts of plant were collected from two sites in Mazandaran province (Farahabad Sari and Pashakola Amol) during July to October 2015. Total phenol and flavonoid contents were determined by colorimetric method using the Folin-Ciocalteu reagent and aluminum chloride respectively. The antioxidant activity was measured by DPPH method and then the antibacterial activity was performed by agar well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of plant extract were determined by broth micro dilution tube method. The results were showed that the total phenolic and flavonoid content and then the antioxidant capacity of plant from Sari region was more than in Amol region. The MIC values which obtained fromSari against Staphylococcus aureus, Bacillus cereus, Shigella dysentery and E. coli were 12, 12, 190 and 390 µg/ml respectively, while these values from Amol were 24, 24, 780 and 1560 µg/ml respectively, which results were also confirmed in agar well diffusion method and then in conclusion the plant extract from Sari region had the highest content of secondary metabolites , antioxidant and antibacterial activity against tested bacteria and there is the direct correlation between phyto chemistry and their antioxidant and antibacterial activity of plant.

Unpasteurized ice cream production in iran is very common as traditional ice cream. Based on extensive researches on the use of herbal compounds for inhibiting the growth of bacteria, this study investigated the antibacterial effects of lemon verbena leaves extract against Staphylococcus aureus and Escherichia coli in traditional ice cream. In order to with the standard principles, traditional ice cream samples containing concentrations of 3, 10, 20, 50 and 100 mg ml ethanol extract of the leaves of the lemon verbena were prepared. And then Samples by bacterial suspension containing 105CFU/ml of Staphylococcus aureus and Escherichia coli were inoculated. And finally antibacterial effects of different concentrations of extract of over time in the freezer -20 ° C in addition to control samples were evaluated. In the case of Escherichia coli the results showed that at all concentrations, between the number of bacteria there is a significant difference compared to control samples (P

Study in order to the introduction of new antimicrobial agents with natural origin is an indispensable necessity. Honey, as a food has antibacterial and antioxidant high potential and the floral origin of honey plays an important role on its biological properties. This research , In order to investigation of antibacterial activity of four types of monofloral honey with different floral origin and a moltifloral honey collected from the bee hive in the golestan province in north of Iran. Evaluation of antibacterial activity against four bacteria using agar well diffusion method was performed. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of honey samples were determined by using broth macro dilution tube method. Results showed antibacterial activity of tested honey samples. Highest antibacterial activity was recorded for multi floral honey by agar well diffusion method at a concentration of 50% with zone of inhibition of 22, 21,16 and 13.66 mm against Shigella dysenteriae , Staphylococcus aureus , Bacillus cereus and Escherichia coli respectively. MIC and MBC values of obtained for multifloral, linden, maple and Astragalus honeys were in the range of %6.25-25% (V/V) and citrus honey showed the lowest antibacterial activity. Overall, the results imply that antibacterial activity of honey samples from different botanical origin is variable and difference between the types of plants used in the production of bee products affect its antibacterial properties.

According to importance of the use of probiotics in food products, recognition of Iranian traditional foods, that contain lactic acid bacteria is important. Lactobacillus is the most important genus of lactic acid bacteria in the dairy products and use of some species of lactobacillus with the probiotic potential can be effective in inhibiting the growth of some pathogens and treatment and control of some gastrointestinal diseases. the aim of this study was to evaluate the antagonistic effect of isolated lactobacillus from traditional cruds of Gorgan township in golestan province against four gastrointestinal pathogenic bacteria. In This study,crud samples sub-cultured on media cultures of MRS agar and after identification of isolated Lactobacillus, evaluation of antibacterial activity of their supernatant against four gastrointestinal pathogenic bacteria was performed by using agar well diffusion method. From 11 samples of traditional cruds, 35 lactobacillus were isolated and identified that the Lactobacillus casei had the most frequent (31.42%). Lactobacillus acidophilus(14.28%), L.
Byfermentans (14.28%) and Lactobacillus animalis (11.42%) in the next positions were frequent respectively. Lactobacillus casei showed the most antibacterial activity against tested pathogenic bacteria ( P

Water resident bacteria are potentially important reservoir of antibiotic resistance genes. This study was performed to evaluate the antibiotic resistance in Escherichia coli strains isolated from raw waters of Golestan province, northern Iran.
In this descriptive study, 26 samples from Ziarat river water (13 samples pre & 13 samples post treatment) and 36 samples from Azadshahr area springs water (18 samples pre & 18 samples post treatment) were collected. 75 numbers of Escherichia coli bacterium samples (50 isolated from river and 25 isolated from springs) identified and isolated from raw waters of Golestan province, northern Iran by MPN method via differential tests. Susceptibility of Escherichia coli strains to 11 antibiotics (Amoxicillin / Clavulanic acid, Ampicillin, Imipenem, Cefalotin, Cefotaxime, Gentamicin, Amikacin, Tetracycline, Nalidixic acid, Ciprofloxacin and Trimethoprim / Sulfamethoxazole) was assayed by disk diffusion Kirby & Bauer’s method.
14 spring's raw water samples and 12 river raw water samples contained Escherichia coli. All of the river and springs samples assayed free from Escherichia coli post treatment. All of the Escherichia coli strains isolated from samples showed the similar phenotypical resistance against to surveyed 11 antibiotics. The most significance resistance to Ampicillin (river 94% & springs 88%), Amoxicillin / Clavulanic acid (river 76% & springs 80%), Tetracycline (river 14% & springs 16%) and Cefalotin (river 8% & springs 16%) viewed. Resistance to Trimethoprim / Sulfamethoxazole (8%), Nalidixic acid (2%) and Ciprofloxacin (2%) just viewed in river samples. All of the river and spring isolates were sensitive to Imipenem, Cefotaxime, Gentamicin and Amikacin and demonstrated intermediate resistance to others antibiotics.
Treatment of raw water from springs and rivers caused the eradication of Escherichia coli. As regard to observed phenotypical resistance in springs’ raw waters, presumably with lack of treatment springs’ raw water can be caused the transmission of antibiotic resistance to human body.