مجله میکروبیولوژی کاربردی در صنایع غذایی
سال نهم شماره 3 (پاییز 1402)

Major depressive disorder is a growing debilitating disease that affects nearly 280 million people worldwide. The etiology of major depressive disorder is considered multifactorial, with diet and the microbiota of the gastrointestinal system being among the most significant factors. Nutritional interventions aimed at improving the diet and modifying the microbiota of the digestive system have significant effects on the recovery of depressed individuals, whose diets often lack vital nutrients and follow inappropriate patterns. In recent decades, the importance of the microbiota of the digestive system in maintaining human mental health and the various effects of diets on its composition have been considered. The Mediterranean diet, known for its health benefits, significantly impacts the gut-brain axis. Understanding these connections can guide the development of optimal nutritional strategies for improving both digestive and mental health of humans. This study aims to provide a broad and scientific review of research on the role of the digestive tract microbiota and the Mediterranean diet in major depressive disorder.

Heavy metal pollution is a critical environmental issue all over the world since heavy metals are non-biodegradable. In this respect, they can accumulate in crops and animals and enter the human body in several ways such as skin, breathing, and the food chain. Lead is one of the well-known toxic metals that is ubiquitous in nature as a result of industrial activities. The presence of lead ions beyond the acceptable ‘safe’ level in food is a serious threat to human health. The current review aims to summarize the research updates on lead toxicity and its effects on plants, soil, and human health. To minimize the effect, different methods are being used to decrease lead concentration in the food chain. Most of the traditional methods are expensive or have little efficiency. Various techniques such as physical, chemical, biological, biotechnological, and Nano-technological methods are available that can be used to reduce heavy metal contamination. Research related to relatively new technology such as biological methods should be promoted and expanded in developing countries where heavy metal pollution has already touched an alarming level. Hence, the present review deals with different approaches to reduce the availability of heavy metals from the food chain.

The importance of probiotics in balancing the microbiota, regulating the function of the immune system, preventing the occurrence and recurrence of infectious diseases, improving digestive disorders and many other benefits has been proven. Investigations in traditional and local fermented products have led to the isolation of lactic acid bacteria in the genera Lactobacillus, Bifidobacterium and Streptococcus, which are usually considered as probiotics. In this study, three local cow yogurts from Bonab city were used to isolate probiotics. Probiotic properties including tolerance to simulated digestive system conditions such as acid resistance, bile salt resistance, hydrolysis of cholesterol and bile salts, antimicrobial properties and physiological tests such as hydrophobicity, auto-aggregation and co-aggregation were investigated and finally selected isolates were evaluated for molecular identification. Of these three traditional products, 11 isolates were investigated, of which 7 isolates belonged to Lactobacilli and 4 isolates belonged to Streptococci. Most of the isolates were probiotic candidates in two or three characteristics, but among them, 2 isolates had better results in most of the probiotics evaluation tests using PCR for the16S rRNA gene analysis.The tests confirmed that both isolates were Lactobacilli. After sequencing and blasting the sequences on the NCBI site, it was found that one isolate is Lactobacillus casei and the other is Lactobacillus rhamnosus with more than 99% similarity. This study confirms that traditional dairy products are important sources for the isolation of probiotic bacteria. Therefore, the identification and optimization of local isolates, which in most studies have better probiotic potential, can pave the way for the production of probiotic supplements.

Today, green synthesis methods for the synthesis of nanoparticles are being considered to replace chemical methods. This study was conducted with the aim of biosynthesis of zinc oxide nanoparticles from cyanobacterial extract and its cytotoxic activity against human hepatocellular cancer cells. First, zinc oxide nanoparticles were prepared by three different methods (supernatant, phycocyanin and with the help of extracellular polysaccharides) from the extract of cyanobacterium Aliinostoc sp and coated with chitosan to stabilize the synthesized nanoparticles. Then the cytotoxic effect of these particles on HepG2 cancer cells was investigated. The statistical analysis of the obtained data was done with SPSS software (version 24) and Excel, one-way analysis of variance and Tukey's test. The results showed that with increasing concentration of zinc nanoparticles, cell viability decreased significantly. So that in the microcoated samples, the lowest survival in (gμ/mL) 200 and then in (μg/mL) 100 zinc nanoparticles with values of 37.40% and 44.03%, respectively, and also in the samples Uncoated, the lowest survival was observed at 200 (μg/mL) and then at 100 (gμ/mL) zinc nanoparticles with values of 46.80 and 56.83%, respectively. The coating of synthesized nanoparticles with chitosan increased the killing effect and the life of cancer cells decreased significantly.

This study aimed to investigate the effect of green tea and green coffee powders at 0, 1, and 2% levels, each separately on the viability of Lactobacillus paracasei in probiotic yogurt. The viability of Lactobacillus paracasei was evaluated in terms of microbial count, pH, and sensory evaluation of yogurt samples in three replicates on days 1, 7, 14, and 21. The results showed that the addition of green tea and green coffee powders to probiotic yogurt significantly increased the viability of Lactobacillus paracasei in all samples compared to the control yogurt (p<0.05). The highest number of bacteria in yogurt samples containing 1% green tea and 2% green coffee contained 13.78 ± 0.17 and 11.54 ± 0.2 log CFU/g, respectively. The lowest and the highest pH values belonged to the yogurt sample containing 2% green tea and 2% green coffee, respectively. The best taste was related to the yogurt sample containing 1% green coffee and the most favorable texture and color was related to the control yogurt sample. The highest scores in terms of overall acceptance were in the control yogurt sample, yogurt containing 1% green tea and yogurt containing 1% green coffee, respectively. In conclusion, the results showed that the addition of 1% green tea, had a good effect on the viability of Lactobacillus paracasei and can be used for commercial production.

Today, Foodborne diseases (FBD) are one the important concerns in the world. The indiscriminate and incorrect use of antibiotics has caused resistance in many bacteria, which is a serious threat to public health. This study was conducted on all food-borne outbreaks that occurred in Semnan Province during one year (April to March 2020). The samples were examined for isolation and detection of Salmonella, Shigella, and Escherichia coli O: 157: H7. Data were collected based on a questionnaire and laboratory data. The results of the study were analyzed by SPSS software version 19. The results showed that the prevalence of outbreaks in women (46 %) was higher than in men and children. The age group of 24 to 44 (31.57%) included the most affected cases. The frequency of the outbreak in the city (%57/31) was higher than in the village (%42/69). The incidence of bacterial agents in water was lower than in food and homemade food consumption was lower than takeout food (44/45%). About (73%) of the bacterial abundance belonged to Escherichia coli species. Shigella and Salmonella contamination of food was 2.9%. According to the results of the present study, women are the most vulnerable groups, and consumption of takeout foods and urbanization are important causes of food outbreaks in Semnan province. Also, Salmonella and Shigella can be considered as important causes of diarrhea in Semnan food outbreaks.