مجله میکروبیولوژی کاربردی در صنایع غذایی
سال هفتم شماره 4 (زمستان 1400)

Wound healing is a complex process which regulates by cellular, humoral and molecular mechanisms. In this study we investigate the effects of wound dressing based on chitosan/cell free supernatant on wound healing. The B. bifidum was cultured in MRS broth and after incubation, cell free supernatant was separated and characterized for manufacturing of wound dressing. Then 37.5% of chitosan solution (10%) was added to supernatant and cast. For wound treatment investigation, 45 male wistar rats divided in 3 groups; control negative (without treatment), chitosan film group, and chitosan/supernatant film group. A full thickness wound was created on the back of the animals and treated with corresponding wound dressing. After direct measurement of wound diameter, 3 rats were sacrificed from each group on day 3, 7, 14 and 21. The wound healing process was identified by histological analysis and TNF-α and VEGF expression assay. Our results showed that the wound healing was completed after 14 days in Chitosan/ supernatant group. While this percentage in negative control and chitosan groups were 94.75 and 78.58%, respectively. Histological analysis showed that chitosan/Supernatant film reduced inflammation and enhanced re-epithelization and deposition of collagen and elastin. This treatment improved wound healing by down regulating of TNF-α and enhancement of VEGF expression.

In this study, the effect of early feeding of probiotic and honey on performance, immune system and intestinal microflora population of broiler chickens were evaluated. The experiment was done in a completely randomized design with 4 treatments, 3 replicates, and 12 birds in each replicate. Experimental treatments were included: 1- Control treatment (48 hours hunger after hatch), 2- drinking water contained 10 grams probiotic preparation/ Litr for 48h after hatch, 3- drinking water contained 5 percent honey for 48 hours after hatch, 4- drinking water contained 10 grams probiotic/ Litr and 5 percent honey for 48 hours after hatch. The results showed that feeding of the experimental treatments had no effect on feed intake of broiler chickens (P>0.05). The broilers fed with probiotic and honey had 6.88 percentage higher body weight gain than control group (P<0.05). Early feeding with honey decreased feed conversion ratio of broiler chicken up to 21 days of age (P<0.05). The birds which consumed probiotic, honey or a mix of probiotic and honey in drinking water had higher antibody titer against sheep red blood cell, and the population of Lactobacilli in their ileal digesta was higher (P<0.05). General conclusion, in regards to the positive effects of early feeding of broiler chickens with probiotic and honey, their usage is recommended during early hours after hatch of chicks to increase body weight, promote immune system, and improve gut health of the birds.

One of the major causes of death in diabetics is kidney complications. Probiotics are beneficial microorganisms that have preventive and therapeutic effects on diseases. The aim of this study was to evaluate the effect of Lactobacillus casei and Bifidobacterium lactis probiotics on histomorphometric changes of kidney in streptozotocin-induced diabetic rats. In this experimental study, 35 male Wistar rats were divided into five groups: control, diabetic, diabetic groups treated with probiotic Lactobacillus casei, Bifidobacterium lactis and a mixture of both probiotics. The diabetic groups (type 1) received streptozotocin at a dose of 60 mg / kg by intraperitoneal injection and the probiotics were gavaged for 35 days. At the end of the fifth week, the levels of insulin, blood glucose, urea, uric acid and creatinine were measured and kidney histopathological changes were examined. The obtained data were evaluated by SPSS software, one-way analysis of variance, Tukey test and p <0.05. In the present study, the levels of insulin, glucose, urea, uric acid and creatinine in the diabetic group showed a significant difference compared to the control group (p<0.001, p<0.05). Significant changes were also shown in the groups treated with Lactobacillus casei and Bifidobacterium lactis in compared with the diabetic group (p<0.05). Increased kidney tissue damage was observed in diabetic rats compared with the control group, while in the groups treated with probiotics compared to the diabetic group. This study showed that in diabetic rat, the use of probiotics Lactobacillus casei and Bifidobacterium lactis has a positive effect on biochemical and histological parameters of the kidney.

today societies are increasingly aware of the significance of food diets for health; thus, any issue related to food safety greatly influences consumer behavior and food diet policies. Thanks to their high moisture content and water activity, rich micronutrients, and neutral pH range, meat and its various products are among the most sensitive food materials to microbial and chemical spoilage. The present paper therefore focused on the antimicrobial properties of bacteriocin on Listeria monocytogenes, Escherichia coli and Salmonella enterica bacteria in comparison to antibiotics. Once bacteriocin was inseminated into sausage samples and kept refrigerated for 12 days, the samples were analyzed in terms of total counts of microorganisms, mold and yeast, Escherichia coli and Salmonella enterica. According to the results of this experiment, the band was less than 10 kilodalton on an SDS-PAGE pattern and the molecular weight of extracted bacteriocin was about 2440 Daltons. A growth inhibition zone was observed for the bacteriocin- treated Listeria monocytogenes, Escherichia coli and Salmonella enterica bacteria. Maximum diameter of the growth inhibition zone was obtained for Listeria monocytogenes, which showed significance difference with tetracycline and gentamycin antibiotics. Also, the control sample demonstrated a significant difference in terms of total count of microorganisms, mold and yeast, Escherichia coli and Salmonella enterica in sausage samples treated with bacteriocin as compared to control treatment. The results of sensory evaluation showed that the sausage samples treated with bacteriocin at a concentration of 1000 ppm had the highest rates of acceptance in terms of aroma, flavor and overall. Finally, the results of this study showed that the extracted bacteriocin had a high potential for use as a natural preservative for meat.

Nanocomposites contain compounds that show beneficial antibiotic properties. The aim of this study was to investigate the antibacterial and antifungal effects of chitosan-functionalized aluminum oxide- titanium oxide nanocomposite on selected microorganisms. In this study, after preparation of aluminum oxide-titanium oxide-chitosan nanocomposite by extracellular biosynthesis method, their antibacterial properties were determined by determining the MIC, MBC and measuring the time of bacterial death. The National Committee for Laboratory Standards was determined and reported by the classical method of preparing consecutive dilutions. The results showed that the nanocomposite showed antibacterial activity at the highest concentrations of 10 and 20 μg / ml for Al2O3 group. While in concentrations (2.5-5 μg / ml) in TiO2 / Al2O3 and TiO2 / Al2O3 / Csn showed strong antibacterial activity against pathogens. It also showed that the highest antibacterial activity of TiO2 / Al2O3 and TiO2 / Al2O3 / Csn is from 6 to 24 hours. However, Al2O3 in all studies showed less antibacterial activity compared to TiO2 / Al2O3 and TiO2 / Al2O3 / Csn. The results of the study also showed that the nanocomposite has no antifungal activity. Aluminum oxide-titanium oxide-chitosan nanocomposites have antimicrobial effect on the studied bacteria.

More than four decades after discovering probiotic strains, the food and dairy industries are increasingly seeking to improve their products with these beneficial yeasts. This study aimed to characterize potential Iranian native probiotics and assess the safety of native yeasts probiotics isolated from fermented products to discover the potential for additive production in the food, dairy, and animal feed industries. In this study, after sampling the fermented products, the samples were identified using biochemical methods such as carbohydrate fermentation and ascospore production in newly optimized culture medium V8NLF containing vegetables. Proteolytic and lipolytic activities were performed to confirm the probiotic potential of selected samples, as well as their ability to grow at different pHs, different dilutions of bile salts and NaCl, sensitivity to common microbial antibiotics, and antimicrobial activity of yeast-produced metabolites against common pathogens. Finally, the optimal strains were molecularly identified. Three isolates with high probiotic potential were identified molecularly based on the results of biochemical and probiotic tests. The Y3 isolate was 100% identical to Saccharomyces cerevisiae, while strains Y23 and Y37 were 96.39% and 97.24% identical to Kluyveromyces marxianus, respectively. According to the findings of this study, Iranian fermented products have a high probiotic potential, and these bacteria can be used in the food and dairy industries, as well as to improve livestock and poultry feed.