مجله میکروبیولوژی کاربردی در صنایع غذایی
سال هشتم شماره 4 (زمستان 1401)

Probiotics are beneficial organisms that can be used as a suitable tool against absorption and possible poisoning by heavy metals. The aim of this study was to investigate the effect of a mixture of native Iranian probiotics (Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus holoticus) on liver tissue changes in male rats infected with cadmium chloride. 21 adult male Wistar rats were divided into 3 groups of 7: control, cadmium chloride, cadmium chloride with a mixture of native Iranian probiotics. Cadmium chloride (3 mg/kg) was injected intraperitoneal and by probiotic gavage (109 CFU/ml) for 30 days. At the end of the test, blood samples were taken from the heart to measure the serum level of liver enzymes, liver tissue was extracted and histological studies of the liver were performed after hematoxylin-eosin staining. Data were compared between groups based on one-way ANOVA and Tukey test. Serum levels of liver enzymes in the group receiving cadmium chloride showed a significant increase compared to the control group and in the group treated with a mixture of native Iranian probiotics showed a significant decrease. Also, morphological changes of liver tissue in the group treated with probiotics showed a decrease in tissue damage compared to the cadmium chloride group. According to the findings of this study, the use of a mixture of native Iranian probiotics (Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus holoticus) can improve the induced damage of cadmium chloride in liver tissue.

Escherichia coli  induced urinary tract infection urinary tract infections is a prevalent acquired infection in Iran. The IutA virulence gene plays a crucial role in the pathogenesis of E. coli, particularly in binding to epithelial cells.  In addition, as a group of probiotics, lactobacilli have an important role in the body and are therapeutically benefits in some cases. This study aimes to molecularly investigate the effect of Lactobacillus casei PTCC 1608 on different strains of uropathogenic E. coli  isolated from urinary infection through PCR. The desired strain of E. coli was isolated from patients with urinary tract infections and investigated through differentiation methods. The IutA gene of the desired strain was evaluated through PCR and then strains with positive genotypes were isolated and the antibacterial effect of Lactobacillus casei was evaluated through dilution and disc diffusion methods in a liquid medium. The antibacterial effect of Lactobacillus casei on antibiotic-resistant uropathogenic E. coli was studies. From a total of 40 samples isolated from the urine of patients with urinary tract infections, the results of MIC-MBC were either positive or negative. The antibiotic sensitivity test at the dilution of 1 to 10 showed an inhibition zone of 9 cm. These results indicated that the isolated bacterium was not resistant to ampicillin and the antibiotic did not lose its therapeutic effect. Moreover, the probiotic used has a therapeutic role and can improve urinary infections.

Today, among 400 types of identified enzymes, approximately 200 types are used in industry. The global enzyme market depict a major portion for xylanase, cellulase and pectinase at around 20%. Xylanase enzyme is used in different industries such as food industry, animal and poultry feed, paper industry and pharmaceutical industry. The aim of this study was to identify xylanase-producing yeast. Effluents from factories and poultry farms in Isfahan were sampled. In order to isolate the xylanase-producing yeasts, the samples were cultured on YPG medium containing beech wood using streak plate method. The enzyme activity was measured by DNS method and protein assay was done by Laurie method. The molecular identification of the best xylanase-producing isolate was performed using PCR followed by sequencing and blasting procedures. The yeast Pichia kudriavzevii strain SBN-IAUF-2 was isolated as the best xylanase producing yeast with the maximum enzyme activity of 1317.56 (u/ml) and maximum specific enzyme activity of 3272/3271 (u/mg) after 48 hours at 30 degree Celsius and aeration speed of 120 rpm. The 18s-rDNA partial sequence of the isolated yeast was deposited in GenBank, NCBI under the accession number of MZ816945. This is the first report of isolation and identification of xylanase-producing yeast Pichia kudriavzevii strain SBN-IAUF-2 conducted in Iran and it is recommended to be applied for optimal production of xylanase.

Nowadays, the consumption of probiotic products is increasing. Adding probiotic bacteria to traditional products is one of the ways to create attraction in the consumption of these products. On the other hand, the survivability of probiotics during the process and storage time is one of the obstacles to expand the use of these products. With this aim, microencapsulated Lactobacillus acidophilus(bead) was produced with sodium alginate and Arabic gum (in 4 concentrations 0.2, 0.4, 0.6, and 0.8%). The produced beads were spherical in shape (aspect ratio 1.06) and had high microencapsulation efficiency (90.52+2.02%). With the increase in the concentration of Arabic gum, the diameter of the outer layer of the beads increased. Since the survivability of the beads containing Arabic gum (0.8%) was 2.47 log CFU.ml-1 in 6 minutes; therefore, this bead was chosen for adding to Chavil yogurt. The survival rate of probiotic bacteria was estimated to be 19.31% and 50.60% in the yogurt sample containing free bacteria and beads separately at the end of the storage period. In the simulation gastrointestinal condition, the survival percentages were 40.9% and 6.95% for free bacteria and bead separately. Chavil yogurt containing beads had the lowest score in the sensory components containing odor, flavor and color, although it had the highest score in the texture parameter. Therefore, the use of double-layer beads containing sodium alginate and Arabic gum may be recommended.

The use of dietary supplements in aquatic diets is one of the most important ways to reduce the stress of rearing operations. In this study, the effect of different levels of Lactobacillus brevis on stress-related indicators including antioxidant and liver enzymes, and hematological indices in rainbow trout were evaluated. In this study, 300 rainbow trout fry (9.5±0.3 g) with five experimental diets including control, LB1 (1× 106), LB2 (1×107), LB3 (1×108), and LB4 (1×109) were fed for 8 weeks. The results showed that the highest levels of superoxide dismutase and catalase were recorded in fish fed LB3 diet. Also, the lowest malondialdehyde value was recorded in the groups receiving LB2 and LB3 diets, which showed a significant difference compared to the control and LB1 groups (p< 0.05). Besides, diets supplemented with LB2, LB3, and LB4 significantly reduced the activity of aspartate aminotransferase and alanine aminotransferase enzymes compared to controls and LB1 (p< 0.05). Also, the level of alkaline phosphatase and lactate dehydrogenase enzymes decreased in all experimental treatments compared to the control group (p< 0.05). In this study, red blood cells count, the hemoglobin value and the hematocrit percentage in the groups receiving LB2, LB3, and LB4 diet significantly increased compared to the control group (p< 0.05) and the highest value ​​was recorded in the LB3 group. Based on the obtained results, the addition of L. brevis, especially in concentrations of 1×109 to the diet of rainbow trout has a beneficial effect on the antioxidant defense, liver enzymes, and hematological indices.

Dudiam melon has a high nutritional value. The bioactive compounds found in the essential oil and extract of this fruit can be used to control the growth of pathogenic bacteria of food origin or spoilage bacteria. In this study, the essential oil of Cucumis melo var. dudaim fruit was extracted by steam distillation method. Methanolic, n-hexane, chloroform, ethyl acetate extracts were also produced by maceration method. The essential oil compounds of this fruit were identified by gas chromatograph (GC) and gas chromatograph connected to mass spectrometer (GC-MS) devices, and the percentage of its compounds was measured. In order to determine the minimum inhibitory concentration of the obtained essential oil and extracts on Escherichia coli, Streptococcus pneumonia, Staphylococcus aureus and Pseudomonas aeruginosa, the Disk Diffusion method was used. The results showed in fruit essential oil, Dehydro Aromadendrene, (Z)-Calamenene and (Z)-Nerolidol are the major compounds, respectively, and the results obtained from the microbial tests showed that the studied bacteria have a significant difference in level of 5% in terms of diameter of non-growth halo. The lowest non-growth diameter halo was related to Escherichia coli bacteria and the highest non-growth diameter halo was related to Pseudomonas aeruginosa bacteria. The minimum inhibitory concentration was for Pseudomonas aeruginosa bacteria. Overall, the fruit essential oil showed more antimicrobial activity against the bacteria than its extracts. These herbal compounds can be used as substitutes for chemical preservatives in foods.