مجله میکروبیولوژی کاربردی در صنایع غذایی
سال چهارم شماره 1 (بهار 1397)

Increasing of industrial fermented foods consumption instead traditional products causes the elimination of many lactic acid bacteria (LAB) especially bacteriocin-producing strains from our diets. Chal (fermented product of camel milk) is one of the best known traditional resources for isolation bacteriocin producing LAB. The aim of this study was evaluating the antimicrobial properties of bacteriocin-like substances produced by lactobacillus fermentum isolated from Chal. For identification of LAB isolates, polymerase chain reaction (PCR) method with specific primer for the detection of bacteriocin-producing strains was used. Then, antimicrobial properties of the LAB isolate and its supernatants obtained from logarithmic and stationary phases as crud, naturalized and treated forms were investigated against some foodborne indicator bacteria and toxigenic fungi based on microdilution and fungal spore spot methods, respectively. Sequencing results of PCR products lead to identification of bacteriocin-producing Lactobacillus fermentum. The antimicrobial effect of the LAB isolate against gram positive indicator bacteria especially Listeriamonocytogenes was significantly (pL. fermentum had respectively more effect on growth of indicator bacteria and toxigenic fungi. Bacteriocin-like substances produced by L. fermentum isolated from Chal because of reduction in growth of foodborne indicator microorganisms showed high potential for using as a bio-preservation agent in food and medicine industries.

The present study was carried out to investigate the effect of Bacillus coagulans Gbi-30 and its culture extracts on the cytotoxicity induced by vegetative form of Clostridium perfringens type A on the HT-29 cancer cell line. For this purpose, extracts with concentrations of 2, 4, 6 and 8% of the supernatant derived from Bacillus coagulans culture in TSB broth medium were added to the vegetative form of Clostridium perfringens type A (NCTC 8239), to the HT-29 digestive cells. For cytotoxicity assessment, MTT and trypan blue staining assays were employed. The results showed that cultivation of Bacillus coagulans and its 2, 4 and 6% extracts were significantly reduced the cytotoxicity of Clostridium perfringens type A using both MTT and staining trypan blue staining. In addition, the lowest cytotoxicity was observed on the presence of the 4% Bacillus coagulans extract on the HT-29 cell line.

Human breast milk contains high amounts of necessary nutrients such as carbohydrates, essential fatty acids, proteins, vitamins and minerals for infants. It is also considered as a continuous source of commensal and potentially probiotic bacteria for infant gut which are leading development and composition of the neonatal gut microbiota for treatment and prevention of intestinal infections. The aim of this study was to evaluate prevalence of lactobacilli existing in breast milk that isolated from healthy women and their potential probiotic properties. In this study, 122 lactobacilli were collected from 100 human breast milk samples. Isolates were identified based on morphology and their results to catalase test and gram stain. The ability of tolerance acidic pH and resistance to bile salts were applied to confirm probiotic potential. Molecular identification was carried out with 16SrDNA and Polymerase Chain Reaction. As 100 samples, 122 Lactobacilli were identified. The most dominant isolates were belonged to the species of casei and rest of them to the species of fermentumplantarum and gassery respectively. 19 isolates were verified with probiotic properties. Molecular studies with 16SrDNA, guaranteed our outcomes. Breast milk is a rich source of lactobacilli with probiotic properties. Since these isolates are safe with human origin, they could be utilized as an additive in food industry and pharmaceutical fields. Administration of probiotic lactobacilli in formula milk, may be useful in order to prevention of infant’s infections.

In order to evaluate the viability of the probiotic bacteria in quinoa-based fermentedfunctionalbeverage, the fermented beverage containing honey (5% w/v) was prepared with 108 cfu/mlLactobacillus plantarum and Lactobacillus acidophilus in the ratio of 50:50. Then, 3%v/vof mint extract was addedto improve the flavor of beverage. The colony count method in MRS agar andpredictive modeling was used to predict the viability of the probiotic bacteria.The results of different models evaluation showed that modified Schnute and zero-order models had the highest accuracy in predicting the viability of bacteria. It is also revealed that the probiotic bacterial keep their viability during 15 days at refrigerated condition in the range of proposed for functional products (at least 106-108 cfu/ml).

The aim of this study was to determine the dietary effects of peptides from enzymatic hydrolysis of canola meal protein with zero (control), 100, 200 and 300 mg of the hydrolyzed protein per kg of feed and the experiments were done in a completely randomized design with triplicates for eight weeks. The results showed that with increasing the amount of hydrolyzed protein in the diet, the specific growth rate and feed conversion ratio in group 4 significantly increased (2.71 ± 0.04) and decreased (1.04 ± 0.01) respectively (P˂0.05). It was also determined that blood cortisol and glucose levels in the second group were decreased in comparison with the control group, but the increase in the dietary peptide increased again. Based on the results, the highest levels of IgM, cortisol and glucose were observed in blood serum of the fourth group (p

Fermentation control with potential application of wheat bran sourdough in novel fermentation technologies is increasing every day to come up to suitable alternatives for additives in bakery. In this research after isolating the dominant starter of the traditional wheat bran sourdough and its identification using PCR and specific primer, it was used to make a traditional sourdough and evaluating the sourdough pan bread qualities by RSM method, under the impression of fermentation time (8, 16 and 24 h), fermentation temperature (26, 32 and 38 °C) and sugar content (1.5, 3 and 4.5 %). In this research, results of evaluating the proportion fitted models showed that by increasing the temperature and fermentation time in a constant sugar content, the titratable acidity (TTA), microbial population dynamics, specific volume, porosity, the total color difference (TCD) and chewiness were significantly increased. However, there was a trend decreasing in the hardness of bread texture (P0.05). Based on the results obtained from the current research, for every dependent variable a model was defined. Also for evaluating the accuracy of the fitted models, lack of fit test was performed and coefficient of variations was determined.