مجله میکروب شناسی مواد غذایی
سال هشتم شماره 1 (بهار 1400)

Nowadays, use of plants in the synthesis of metal nanoparticles, which have antimicrobial activity, is considered. The aim of present study was evaluating biosynthesis of silver nanoparticles from aqueous extract of rosemary and then investigating the effect of these nanoparticles and mancoseb toxin on soft rot bacteria isolated from carrots, potatoes and onions during storage. The biosynthesized silver nanoparticles were analyzed by ultraviolet and FTIR spectroscopy. Soft rot bacteria were isolated and identified using selective and specific culture media from carrots, potatoes and onions. A pathogenic isolate from each sample with the highest pathogenicity was selected for the tests and their minimum inhibitory concentration (MIC) was evaluated against the experimental treatments. The MIC of the pathogen isolates against the 2580 mg/ml of silver nanoparticles and 1000 ppm of mancoseb were 88.88% and 100%, respectively. The mean percentage of vegetable contamination with pathogen isolate in the presence of silver nanoparticles in the third month of storage was 70%, 80% and 70% for onions, potatoes and carrots, respectively, and average percentage of vegetable contamination with pathogenic isolates in the combined control of bacteria with silver nanoparticles and mancoseb toxin at the third month of storage for onion, potato and carrot were 45, 40 and 40%, respectively. According to obtained results, the combined control of biosynthesized silver nanoparticles and Mancoseb can be used to control of soft rot bacteria in carrot, potato and onion.

Despite significant advances in radiation therapy and cancer treatments in the past 30 years, resistance to chemotherapy is a major obstacle in the recovery of patients with cancer. Resistance to chemotherapy drugs inhibits the recovery process. This study aims to evaluate the anticancer activity of the hydroalcolic extracts of Rosemary, Peganum, and Coffee on growth inhibition of MCF-7 cell line and determine the rate of growth inhibition of pathogenic bacteria isolated from food. We examined cytotoxicity effects of three different concentrations (60,120,250 μg/ml) of Rosemary, Peganum, and Coffee extracts on MCF-7and HDF cell lines. The cell lines were grown in RPMI supplemented with 10% FBS, 1% penicillin, and streptomycin. The cells were allowed to incubate at 37ºC in an atmosphere that contained 5% CO2 and 95% humidity. The standard MTT assay was performed to estimate cell viability after treatment by Rosemary, Peganum, and Coffee extracts. The extracts were also used with MIC on Staphylococcus aureus and E. coli bacteria isolated from food. The results of the MTT assay showed that the Rosemary, Peganum and Coffee extracts had time-and concentration-dependent anticancer activities on the MCF-7cell line compared to HDF cells statistically significant (p<0.01). As the Rosemary extract had more effect on the control of cell proliferation than the other two extracts. Also, these extracts at different concentrations had an inhibitory effect on food pathogenic bacterial growth. Our results have suggested that these plants extract is a potential candidate, either alone at pre-determined doses, for the dietary supplement suitable for the inhibitory effect on food pathogenic bacterial growth and cancer cell lines.

Sarcocystis is one of the most prevalent protozoan parasite that infected humans and many animals worldwide. Cattle as one of the sources of meat products for the human is exposed to contamination with these parasites.The aim of this study was the determination of prevalence of sarcocystis in slaughtered cattle in Kashan region, 2019. In this cross-sectional study, 162 meat samples from 54 slaughtered cattle ( three samples from muscle, esophagus, and diaphragm of each cattle) were collected. After recording of data, about 15-20 gram of each samples were digested in digestion solution overnight at 27 °C according to Douby method. Two smears prepared from sediment and stained by Giemsa stain, and microcopy observed for Sarcocystis cystizoite. Totally, 94.4% of samples were positive for sarcocystis spp. Microscopic cysts were positive in 90.7%, 87% and 81.5% of muscle, esophagus, and diaphragm samples, respectively. The results showed no significant difference between different muscles. Only one case of the macroscopic positive sample was seen that simultaneous was infected microscopic. The present study showed a high prevalence of infection to Sarcocystis in cattle slaughtered in Kashan similar to another region of Iran. So conduct of preventive measures for the reduction of animal infection and Properly cooked meat before consumption are recommended for the prevention of human infection.

Methicillin-Resistant Staphylococcus epidermidis is an important pathogen that causes infectious diseases whose treatment is extremely formidable. Staphylococcus epidermidis enterotoxins with effects on intestinal epithelial cells can are be causing Create food poisoning in people. The aim of current study is to the identification of MRSE strains associated with food poisoning outbreaks in Isfahan. During six- months, 60 clinical specimens to isolated from strains of Staphylococcus epidermidis were screened. Following identification strains, MRSE isolates were isolated by PCR method and, and then antibiotic resistance pattern of them was determined by Kirby – Bauer method. The presence of the sea, seb, sed and, sei genes was analyzed by PCR. 45 isolates of Staphylococcus epidermidis were isolated from 60 samples, 30 isolate (66.6 percent) were MRSE. MRSE isolates exhibited the highest rates of resistance to penicillin (80 percent), and cefoxitin (56.6 percent), while they showed the lowest resistance to levofloxacin (13.3 percent), and rifampicin (6.6 percent). The prevalence rate of Moreover, the frequency of enterotoxin genes sea, seb, sed and, sei was 60 percent, 63.3 percent, 13.3 percent and, 76.6 percent respectively, in the isolate. In this study, high percentage of MRSE isolates were antibiotic resistant and produced enterotoxin. Considering that these toxins are superantigen and can more intense the complications of clinical and nosocomial infections, detecting and rapid treatment of these infections are essential.

The aim of this study was to investigate the antimicrobial activity of ethanolic extract Zataria multiflora, Salvia verticillata, Froriepia subpinnata on Pectobacterium carotovorum and Pseudomonas aeruginosa.An experiment was conducted at the in vitro condition. The extracts were prepared by the maceration method.The antimicrobial activities were investigated using the micro broth dilution method and by determining the minimum inhibitory concentration(MIC), minimum bactericidal concentration (MBC) and also their synergistic properties.Variables included extract types, different concentrations of extracts and bacterial strains.The minimum inhibitory concentration of Z. multiflora varied between 3.12 to 6.25 mg/mL; that of S. verticillata extract was between 12.3 and 25 mg/mL, and for the F. subpinnata was 12.5 to 25 mg/mL.The combined use of the extract of Z. multiflora and S. verticillata showed that there was an antagonistic effect between the two extracts in the case of P. carotovorum and synergic effect for P. aeruginosa.The results of the combined use of extracts of Z. multiflora and F. subpinnata and checkerboard dilution Modified(FIC) assay showed a synergic effect on P. carotovorum and antagonistic effect on P. aeruginosa.The combined use of the S. verticillata and F. subpinnata showed a synergic effect on both bacterial strains (0.54). A comparison of the results of inhibitory effects revealed that Z. multiflora extract had more potent antibacterial activity than S. verticillata and F. subpinnata. P. carotovorum was more sensitive than P. aeruginosa.FIC analysis showed that in the studied bacteria the combined application of S. verticillata and F. subpinnata extracts had better results than other combined extracts.

Several factors are considered during production of yogurt, among which selecting the accurate starter and or adjunct culture is one of the most important factors. This study was aimed to measure the degree of proteolysis, ACE-inhibitory, microbial and antioxidant activity of yogurt produced by a commercial starter supplemented with native co-cultures isolated from traditional yogurts during a 20-days of storage. All treatments were also compared with the commercial culture as control. Initially, five strains of Lactobacillus lactis, two strains of Lactobacillus helveticus, one strain of Lactobacillus delbrueckii, one strain of Pedicucus pentosaseus and one strain of Vissella sibaria used to inoculate into 40 yogurt samples in a completely randomized factorial design with two replications. The samples were kept at 5 ˚C for 20 days and investigated for their physicochemical properties (pH and acidity), degree of proteolysis, ACE-inhibitory, microbial antioxidant activity. The results of statistical analyses showed that application of native co-cultures was significantly increased the degree of proteolysis, ACE-inhibitory, and antioxidant activity of the samples. Our findings showed that, yogurt inoculated with the native strains of Lactobacillus lactis had the highest scores for ACE-inhibitory and antioxidant activity. In all co-cultures, ACE-inhibitory (47%) and antioxidant activity (58%) exhibited a positive correlation with proteolysis. Our results show that co-cultures greatly affect the ACE-inhibitory and antioxidant activity, which can be used in the production of functional food stuffs.

Due to developing consumption of ready-to-eat food and influence of them on foodborne diseases, microbial changes in the various kinds of the foods at the factories and food markets in Alborz province were examined. For this purpose S.aureus bacteria, coliforms, E.coli, molds and yeasts, and bacterial total counts, in 200 samples of semi-cooked (falafel, fishfinger, fried-fish, fried-chicken, meat-cutlet, cordon-bleu, kookoo-sabzi, fried-shrimp, chicken nugget, schnysel chicken , schnysel forming) [A], frozen raw (chicken-kebab, frozen chicken arm, chicken burger, 30%hamburger, 60%hamburger, 75%hamburger, 85%hamburger, 85%finger kebab)[B], and cocked refrigerated (55%cocktail sausage, 55%hot dog, German sausage)[C] were studied. The amount of the bacteria after storage in the stores were more than the factories, in all groups (P≤0/05). Total bacterial count and coliforms, in the C group was less than other groups and between the A and B groups didn’t find any statistical difference. The C group didn’t contain the Escherichia coli, and it was higher in B group than A group. The highest and lowest molds and yeast were founded in B and A samples, respectively. The highest number of Staphylococcus aureus bacteria was related to the B group (P≤0/05). The increase of microbial changes in hyperstores compared to factories can indicate that ready to eat storage has done in abuse time-temperature conditions. In addition to the ecological characteristics of these microbes, cross-contamination by personnel manipulation, improper handling and transportation, undercooked cooking, (especially in semi-cooked food) and improper use of the freezing system can play a significant role in this microbial increase.

Rosa canina fruit extract with its high content of bioactive compounds such as vitamin C, carotenoids, and polyphenolic compounds, can be used as a natural preservative in meat products. This study aimed to investigate the antimicrobial and antioxidant activity of Rosa canina fruit extract to improve durability at refrigerator temperature. For this purpose, ethanolic extract of Rosa canina fruit was prepared by microwave at three concentration levels (0.5%, 1%, and 2%) and added to chicken samples. An extract-free sample was considered as a control. All specimens were kept at 4°C for 10 days. Microbial properties including Total bacterial count, Escherichia coli, Staphylococcus coagulase-positive, and Salmonella, physicochemical properties including fat oxidation, free radical inhibition, methemoglobin absorption, pH, and volatile nitrogen during the first, fourth, seventh, and tenth days were tested. The results showed that Rosa canina Fruit extract significantly reduced the mean (P<0.05) in Total microbial load count, Staphylococcus and Escherichia coli bacteria compared to the control sample. Salmonella's search results were negative. The amount of fat oxidation, free radical inhibition, methemoglobin absorption, pH, and nitrogen volatility decreased significantly (P<0.05) in the treatments compared to the control sample. In this regard, the concentration of 2% (highest concentration) of the extract was introduced as the selected treatment. According to the results, Rosa canina fruit extract has a high potential to increase the shelf life of chicken meat kept at refrigerator temperature and as a suitable alternative for chemical preservatives will be able to be used for industrialization.