مجله میکروب شناسی مواد غذایی
سال نهم شماره 3 (پاییز 1401)

Probiotics have been a good and healthy food source for humans for centuries. In the meantime, microalgae are always considered as useful dietary supplements. The combination of microalgae and probiotics leads to the production of fermented dairy products that not only increase the quality of food, but also increase their nutritional value for consumers by increasing the number and shelf life of probiotic bacteria. In fact, as the number of live probiotics in the diet increases, consumers will receive more probiotics at the time of consumption. In this review article, we tried to investigate the effect of probiotics and prebiotics on the use of microalgae supplements on various fermented dairy products. In addition, by reviewing the latest available articles, the effect of using microalgae supplements on physiological, chemical and microbiological properties and sensory of dairy products were examined.

Using from medicinal smokes has been customary in treatment of many diseases by bacteria in Iran and especially ChaharmahalVaBakhtiari province. The aim of this investigation was to study the antimicrobial effects of medicinal smoke of the Teucrium polium on food-borne bacteria in vitro condition. Components from an indirect heating of Teucrium polium were extracted in the form of two organic liquid phases of 1 and 2. Plant extract was also extracted using the ethanol solvent. Then, the antimicrobial effects of two organic phases were analyzed against Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli bacteria. Minimum inhibitory concentration (MIC) and minimum bacteria concentration (MBC) were determined using the tube dilution method. Statistically significant difference (P <0.05) was seen between the antimicrobial effects of the organic phases of smoke and extract of the Teucrium polium on tested bacteria. Organic phase 1 of smoke at concentration of 2000 ppm had the highest diameter of the growth inhibition zone on tested bacteria. Tested organic phases had the highest antimicrobial effects on the Staphylococcus aureus. Antimicrobial effects of the organic phases on Gram-positive bacteria were higher than Gram-negative. According to the cheap, low cost, high efficiency and safety of the procedure of the smoke production from the Teucrium polium plant and also its higher antimicrobial effects than extraction, using from organic ophase 1 from the smoke condensate of the Teucrium polium plant is recommended to elimination of harmful bacteria and the cause of corruption in food products as well as increasing their shelf-life.

The aim of this study was to evaluate the antibacterial properties of lemongrass essence (Cymbopogon citratus) against pathogenic bacteria. For this purpose, the antimicrobial activity of the essence was determined by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against five pathogenic bacteria and food contamination factors such as gram- positive bacteria such as Bacillus cereus and Clostridium botulinum and gram- negative bacteria such as Escherichia coli and Pseudomonas aeruginosa and Shigella. The results showed that the highest MIC and MBC were observed against Shigella Gram-negative bacteria (MIC 566.66 ppm, MBC: 658.33). The lowest MIC and MBC values were observed against Clostridium botulinum (MIC 258.33 ppm, MBC: 408.08). Antibacterial activity of different concentrations (100, 250, 500, 750 and 1000 ppm) of the essence was also determined by the diameter of the inhibition zone and compared with the antibiotic tetracycline. The diameter of the growth inhibition zone of different concentrations of Bacillus cereus essence is 10.29- 24.83 mm, Clostridium botulinum is 9.65- 28.72 mm, Escherichia coli is 8.25- 19.58 mm, Pseudomonas aeruginosa 6.41- 18.15 mm and 5.41- 16.41 mm respectively. In total, concentrations of 750 and 1000 ppm had the highest antimicrobial activity compared to antibiotic tetracycline. Based on the results of this study, lemongrass essence has an acceptable antimicrobial effect and can be used as an alternative to common antimicrobial compounds.

Exopolysaccharides, compounds derived from the metabolites of probiotic bacteria, play an important role in regulating the immune system. Considering the role of culture medium in the production efficiency of exopolysaccharides, the aim of this investigation was to optimize the culture medium for the production of exopolysaccharides by Lactobacillus fermentum, Lactobacillus plantarum, and Lactobacillus acidophilus. In addition, the effect of dextrose and sucrose on the production of exopolysaccharide was investigated using paper disks impregnated with probiotic culture medium. Then, the production efficiency and inhibitory power of exopolysaccharide free radicals were investigated in the culture medium after whey alone and with yeast extract and peptone. Sucrose as a carbon source of optimal culture medium for the production of exopolysaccharide is more suitable than dextrose. In addition, the production efficiency and inhibition of free radicals by exopolysaccharides of native probiotic strains in all culture media was significantly higher than commercial strains, which could be due to different enzyme mechanisms. In the cell wall of L. fermentum and L. plantarum is involved in the breakdown of sugars, which plays an important role in the formation of the final structure of the exopolysaccharide. Therefore, it is suggested that for L plantarum and L fermentum, YS culture medium with high production efficiency should be used and there is no significant difference for ATCC bacteria. For medicinal use, we recommend YD culture medium for NIMBB003 bacteria, SS culture medium for NIMBB014 bacteria, and SD culture medium for ATCC bacteria, which has better antioxidant properties and efficiency.

Maintaining the desired quality of dates, clearing them of contaminants and proper packaging to increase shelf life are among the priorities of the country. Since the use of edible coatings with vegetable oils is one of the ways to prevent the growth of microorganisms, was used natural polymers including zein and chitosan, alone and along with pimpernel oil on microbial activity of Mazafati date fruits, for one year at 4 and -18°C and the second year at 10°C was investigated. The obtained data were analyzed using SPSS software and Duncan's mean comparison was performed. The results showed that this dates with 32% moisture content had a high microbial load. The fungi of Aspergillus niger, Aspergillus flavus, Rhizopu stolonifers, and Alternaria alternata were grown on it. These fungi, in particular Aspergillus niger, were involved in its rotting and lactic acid bacteria in its rancidity. By doing this research, the number of Aspergillus niger fungi was reduced by logarithmic three cycles using zein and chitosan edible coatings with pimpernel oil; and penicillium fungi were completely eliminated. In general, the lowest number of microbial growth was observed in Zein treatment 362.5 & 150 log cfu/g , in the first and second years respectively, and the highest number was observed in the control sample 10750 & 1025 log cfu/g. The use of anise oil also had an effect on reducing the overall count of microorganisms. Finally, according to the microbial results, the use of zein treatment is recommended.

Enterococci are among the lactic acid bacteria with probiotic potential which are found in dairy products and especially in fermented products. The study aimed to isolate enterococci from raw milk of Jersey cows and its fermented products as well as to determine some probiotic properties of the isolates. Five specimens from each of raw milk, buttermilk, yogurt, cheese, and butter were obtained. Twelve isolates of Enterococcus faecium, Enterococcus avium, and Enterococcus faecalis were isolated. The antimicrobial effects of the isolates were investigated on indicator microorganisms. All isolates had an inhibitory effect on these microorganisms. Escherichia coli was more sensitive than the others. Pseudomonas aeruginosa and Listeria ivanovii followed, and the lowest susceptibility was observed in Listeria monocytogenes, Bacillus cereus, and Klebsiella pneumoniae, respectively. Overall, gram-negative microorganisms were significantly more sensitive than gram-positive microorganisms (p≤0.05). In the study of resistance of isolates in culture medium containing 0.3% bile, out of 12 isolates obtained from the tested samples, two isolates of E. avium (40%), three E. faecalis isolates (100%), and one E. faecium (20%) were found to be resistant. Amongst, one isolate of E. avium was resistant to acidic conditions. In general, milk and fermented products can be considered rich sources of Enterococcus species, a small number of which are resistant to the human gastrointestinal tract environment. Of course, these isolates must be further evaluated for safety.

Neosporosis is the main cause of abortion in cattle in Iran and other parts of the world, which is caused by a parasitic protozoan Neospora caninum . The economic effects of Neosporosis are reduced milk and meat production in cattle. Transmission of N.caninum is possible through vertical and horizontal routes. Some studies have been conducted on the importance of vertical transmission during infancy, through colostrum and milk. Most studies in Iran to investigate the incidence of N.caninum in cattle are based on the search for anti-parasitic antibodies in the blood serum and limited studies have been performed on milk. The aim of this study was to investigate the presence of N.caninum genome in raw cow milk using PCR method to evaluate the vertical transmission of this parasite. In this study, 300 samples of raw cow's milk were collected from traditional farms in Yazd province. The results of this study showed that 54 cases (18%) of 300 samples of cow milk were infected with N.caninum genome. The findings of the present study indicate a high presence of N.caninum infection and showed that infected cow's milk plays an important role in the transmission of Neosporosis in newborn calves. Based on these findings, control and eradication programs, including vaccination, are necessary to prevent and reduce the economic losses of this protozoan infection in cattle.

Pseudomonas aeruginosa a potential risk factor for food poisoning especially in aquatic foods like shrimp. In order to determine and compare the rate of infection in different species of shrimp in two seasons of summer and autumn in Isfahan and Chabahar cities, the abdominal muscle of 35 shrimps in each season of each city were sampled. Samples were homogenized in peptone water medium, then incubated and cultured in PCA medium. Suspected colonies were isolated and then confirmatory tests of Pseudomonas aeruginosa and confirmation of the presence of nanI, the specific gene of Pseudomonas aeruginosa by PCR.In summer, in Isfahan and Chabahar, 48.5% and 25.7% were infected respectively. In autumn, the prevalence was 22.9% for Isfahan and 20% for Chabahar, respectively. In Isfahan, the highest rate of infection was related to Metapenaueus affinis and the lowest to Penaeus semisulcatus in summer. In autumn, the highest number of infected samples was related to Penaeus merguiensis and the lowest to Penaeus semisulcatus. In Chabahar city, in both seasons, the most infected samples were related to Metapenaeus affinis, and the lowest to Panaeus semisulcatus and in autumn was related to both Penaeus semisulcatus and Litopenaeus vannamei.There was a high prevalence of this bacterium in samples of different shrimp species in both seasons and both cities, which indicates a high risk of food poisoning of Pseudomonas aeruginosa due to improper consumption of shrimp. Cold chain observance during storage, transportation and sell of shrimp will be very effective in controlling this problem.