Coliforms and Escherichia coli are major microbial indicators in the accessing the quality of foodstuffs. The presence of these bacteria in foods is considered as an indication of fecal contamination. E. coli O157:H7 is the most pathogenic strain that is transmitted to human through animal-foods. This study was performed on 100 traditional cheese samples manufactured in Maragheh rural to determine the seroprevalence of E. coli. The samples were analyzed with standard microbiological methods followed by biochemical confirmatory tests. Afterwards, the isolates were assayed for the detection of O-serotypes using direct agglutination method. Among the 100 cheese samples, E. coli O157 serotype was not detected in any sample. However, other E. coli serotypes including 32 isolates of non-O157 serotypes were detected. Among the isolates, enter opathogenic, enter otoxigenic and enterohaemorhhagic serogruops was also detected.

Cheese is a product consisting of fat and milk protein, along with calcium and phosphorus that are combined with milk protein in various ways. Due to the importance of cheese consumption among the people of Iran and considering that this product is one of the most important dairy products and according to available statistics, about 20% of the milk produced in the dairy industry is converted into cheese, of which the share of production Traditional cheese is about 80%. The purpose of this study was to evaluate the level of contamination of traditional cheeses offered in different areas of Karaj city. The present descriptive cross-sectional study was conducted in the summer of 1398 by sampling different parts of the north, west, east, south and center of Karaj city. Four types of bulk cheeses of Tabriz Ligvan, lactic, white and gypsum in five geographical areas with three replications were examined for the presence of Staphylococcus aureus. The present study shows the contamination of traditional cheeses offered in Karaj city and its different areas, although the rate of contamination in the west of the city was higher than other areas. Among the regions, the eastern region with the lowest level of pollution among other regions and the presence of contamination only in gypsum cheese, was identified as the least dangerous region. In contrast to the existence of high pollution in all four types of cheese studied in the west of Karaj city, based on the results of this study, this part of Karaj city was introduced as the most dangerous area in the consumption of traditional cheeses.

Aim and background: Lactobacilli are Gram-positive, catalase-negative, non-spore forming, rod-shaped organisms. So far, more than 90 species of these bacteria have been identified. There are several strains of probiotic Lactobacilli in a wide range of human food products. Identification of these bacteria in traditional dairy products makes it possible to use them in the production of delicious industrial dairy products. The selection of reliable methods for the identification of Lactobacilli is of a particular importance. Biochemical methods are time consuming and ambiguous. Molecular methods are more appropriate and precise and can be a substitute for previous methods. The purpose of this study is the isolation of Lactobacilli from bacterial flora in Bandar Abbas traditional cheese and identification these bacteria by using PCR as an effective tool for the recognizing the isolated strains. Materials and methods: Fifty samples of traditional cheese were collected from Bandar Abbas and strains were obtained by phenotypic methods. 16 s rRNA primers were used to identify their molecular identity. Then the PCR product was sent to Poya Gene Gostar for sequencing. Obtained sequences were blasted in NCBI GenBank. Results: 3 strains of Lactobacillus include Lactobacillus murinus, Lactobacillus helviticus and Lactobacillus planatrum were identified. Conclusion: These three strains improve the quality of dairy products in this area and can be used in products manufactured in the industry.

Introduction: Lactic acid bacteria (LAB), as the main dairy starters, play an essential role in the production of volatile compounds such as proteolytic and lipolytic enzymes involved in cheese processing, suppression of pathogenic microorganisms, formation of curdling tissue, and creation of a fresh acidic flavor.Materials and Methods: In this study, the LABs were isolated from fourteen samples of traditional cheeses in different part of Iran. The isolates with the highest cheese production capacities were selected and subsequently various factors including pH and temperature were evaluated on their activity. Besides, the viability of strains, which were used to produce traditional cheeses, under microencapsulation and gastric simulation conditions was also investigated. Finally, the best LAB strains (BCC7 and BCC10), with desirable characteristics for cheese production, were molecularly identified by using the 16srDNA test.Results: This study showed that the survival rate of BCC7 and BCC10 isolates microencapsulated with sodium alginate/chitosan were higher than free cells in the storage condition of -80 °C after six weeks by 23.50% and 20.78%, respectively. Moreover, the quantification of the activity of BCC7 and BCC10 strains at a temperature of 4 °C yielded 11 107 CFU/ml and 9 107 CFU/ml, respectively; exhibiting a greater activity than that observed at a temperature of 28 °C. Furthermore, the preservation of their morphological and biochemical properties was observed.Discussion and Conclusion: The present study determined the sequences of the most efficient lactic acid strains, and subsequent analyses indicated that the BCC7 and BCC10 strains isolated from native cheese samples, were corresponded to Enterococcus faecium strains SKL-4 and 276-18, respectively. Therefore, these two strains are good candidate to introduce to the market as high-quality starters for dairy industries.

Dairy products play an important role in the nutrition and health of people and cheese is a source of protein, fat, and minerals. Due to its high importance, it has a special position in the diet of the people. However, its contamination with pathogenic microorganisms such as staphylococci can endanger human health. In this study, 46 traditional kinds of cheese including 23 samples of salt water cheese and 23 samples of pot (Kope) cheese were prepared from different regions of the city of Maku and the rate of Staphylococcus aureus coagulase positive was evaluated by culture method. The results of biochemical tests showed that 28. 2 % of the traditional cheeses had Staphylococcus aureus coagulase which 17. 3 % of them were salted cheese and 10. 9 % of them were pot (Kope) cheese. The results of most probable number test showed that 19. 5 % of traditional cheeses had more than 110 colonies per gram of cheese. It was found that 6. 5 % of pot (Kope) cheese and 13 % of salt water cheeses had an infection rate of more than 110 colonies per gram of cheese. Regarding the high prevalence of Staphylococcus aureus infection in these traditional cheeses, milk heating and compliance with hygienic conditions are essential for the preparation of these cheese.

Biogenic amines (BA) are nitrogenous compounds that possess biological activity. The source of production is the microbial decarboxylation of amino acids. This compounds are found in various types of cheese. The aim of this work was to evaluate the BA content of some traditional cheeses in West Azerbaijan province Iran. For this purpose, 70 samples of Koopeh, 10 samples of Lighvan and 5 samples of Red Salmas cheeses were obtained from local supermarkets of different cities of West Azerbaijan province. After preparation of samples, biogenic amines content was evaluated by modified HPLC method. The presence of histamine, cadaverine, putrescine and tyramine in tested cheeses were observed. Total amount of biogenic amines was highest in Red Salmas cheese with 1426.91 ppm. It followed by Lighvan cheese and Koopeh cheese with 1008.98 and 517.71 ppm, respectively. Putrescine, cadaverine, histamine and tyramine were detected in Koopeh cheese at levels up to 156.09, 282.34, 70.80, 8.48 ppm respectively. These amines were detected also in Lighvan cheese at levels up to 277.53, 342.74, 37.58, 351.12 ppm and in Red Salmas cheese samples at levels up to 438.03, 701.05, 105.21, 182.62 ppm, respectively. Large amounts of biogenic amines can indicate non hygienic conditions and contamination of used milk for cheese production.

Contamination of milk and its products with pathogenic organisms such as Listeria could be considered as a health threat for the consumers. The aim of this study was to investigate the occurrence and diversity of Listeia spp. in traditional cheeses of Tabriz area and to assess antibiotic resistance, biofilm formation and thermal-resistance of the isolates. A total number of 100 traditional cheese was collected randomly. Listeria spp. were isolated and identified using conventional culture methods. According to the results, 12 out of 100 cheese samples were found positive forListeria spp. Amongst, 5 and 7 isolates were identified as monocytogensand ivanovii, respectively. The highest rate of resistance was observed for oxacillin (100%) and nalidixic acid (75%), and the highest rate (100%) of sensitivity was related to cotrimoxazole, tetracycline, gentamicin, erythromycin and vancomycin. Results of biofilm assay reveled that all 5 strains of L. monocytogens produced low amount of biofilm, meanwhile strains ofL. ivanovii produced a range (weak, moderate and high) of biofilm level. Based on thermal-resistance outcomes, thermalisation process had insignificant impact on Listeria strains; whereas application of “rapid pasteurization” process for 5 sec, reduced the populations of both Listeia specis to below the detectable limit (P<0.01). In the case of batch pasteurization, two Listeria species demonstrated significant (P<0.01) degree of resitsnce. Since L. monocytogenes, and in a lesser extent L. ivanivi are human pathogens of concern, it was concluded that traditional cheeses of Tabriz area could pose a health hazard dealing with Listeria.