جستجوی مقالات مرتبط با کلیدواژه « لاکتوباسیلوس رامنوسوس » در نشریات گروه « زیست شناسی »

 Probiotics play a very important role in improving the normal intestinal flora and inhibit the growth of harmful bacteria in the gastrointestinal tract and are also important for therapeutic purposes. This study aimed to optimize biomass production by Lactobacillus rhamnosus ATCC53103 (GG) using the experimental design process.

 In this study, the probiotic bacterium Lactobacillus rhamnosus was used. Plackett-Burman design method was used for the optimization. Fermentations in basal and optimized cultures were performed in 1300 liter Parspad Company's fermenters.

 The results showed that beet molasses, glucose, and casein have the greatest effect on biomass production by Lactobacillus rhamnosus. Glucose with casein and beet molasses have a synergistic effect and increasing the concentration of glucose with increasing the concentration of two other factors increases the production of the biomass. Based on the results obtained, after optimization, the optimal culture medium for biomass production by Lactobacillus rhamnosus has the following compounds g/L-1: glucose 112.50, beet molasses 56.25, casein 18.75, yeast extract 18.75, K2HPO4 13.13, Tween 80 1.88, MgSO4. 7H2O 0.3750, MnSO4. 4H2O 0.0750, CaCl2. 2H2O  0.1875 and Simethicone1.25. The biomass production in optimized conditions was increased more than 2-folds higher than the basal medium.

 Biomass production by Lactobacillus rhamnosus on a semi-industrial scale was carried out in 1300 liters fermentors. Therefore, the results of this study can be used in the industrial production of Lactobacillus rhamnosus biomass. Also, commercial production under fed-batch and continuous culture conditions is recommended.

According to the FAO annual report, 10 percent of the world's food products are contaminated with fungal toxins, among which aflatoxins have the most contribution as compared to others. This research was aimed to assess the ability of Lactobacillus rhamnosus strain GG in the reduction of aflatoxin B1 (AFB1) in a simulated human gastrointestinal tract containing sterilized milk.   For this purpose, the bacterial count and aflatoxin concentration were adjusted to 1×1010 cfu/ml and 5 ppm, respectively, where artificial gastrointestinal tract discharges were inoculated in the simulated environment. In this study 6 treatment groups were assessed in the presence and absence of bacteria, sterilized milk, and gastrointestinal juice suspension. The concentration of residual aflatoxin was determined using high-performance liquid chromatography (HPLC) and purification by Immunoaffinity column.   The reduction of aflatoxin B1 at all treatments was determined using HPLC with a detection limit of 0.25 mg/ml and a quantification limit of 0.75 mg/ml. The mycotoxin recovery rate was between 89% and 94% for AFB1. The aflatoxin B1 calibration curve with a correlation coefficient of 0.95 was linear in the concentration range of 1 to 10 ng/ml. The highest and lowest average removal percentage of aflatoxin B1 was observed for 5 and 1 treatments (58.8 ± 0.018 and 13.86 ± 0.017) respectively, where a significant difference in removal percentage was observed among six treatment groups.   The results indicated that beside L. rhamnosus strain GG, gastric and small intestine juices are suitable to eliminate or reduce aflatoxin B1, as well.

Hyaluronic acid (HA) is a major component of the extracellular epithelial, neural and connective tissue of vertebrates, as well as of extracellular microorganisms. This polysaccharide has specific applications in ophthalmology, orthopedic, cosmetics and tissue engineering due to features such as high viscosity and biocompatibility. Animal tissues and streptococci have a major role in producing hyaluronic acid, but because of problems such as protein contamination and the presence of endotoxin, attention has been drawn to the GRAS bacteria for producing hyaluronic acid. Lactobacilli are probiotic bacteria that have diverse uses. The production of biochemical macromolecules by this group of bacteria is a priority because they are GRAS. Hyaluronic acid production for the first time in these GRAS bacteria including Lactobacillus acidophilus PTCC1643, Lactobacillus rhamnosus PTCC1637, Lactobacillus casei PTCC1608 and Streptococcus thermophilus PTCC1738 were investigated. In the first step, Hyaluronic acid was isolated from specific culture medium and partially purified by ethanol precipitation daily for 96 hours. Carbazole method was used to measure the production of hyaluronic acid. Based on results, Lactobacillus rhamnosus produced about 0.4 g/l of hyaluronic acid at 96 hours. The increase of HA was also investigated using optimization culture medium by Taguchi design. By using this method, the optimum points of the factors were determined and the hyaluronic acid production increased by 162%.

Addition of prebiotic and also some compositions which can affect survival rate of probiotic strain is considerable several years ago. So, in this study, production of heated and non-carbonated probiotic doogh and study of its chemical composition and sensorial properties were explored. Five treatments were prepared, T1 as a control sample without probiotic strain and maltodextrin, T2 and T4 containing 1 and 2% of maltodextrin respectively and 108 cfu/ml Lactobacillus acidophilus, T3 and T5 containing1 and 2% of maltodextrin respectively and 108 cfu/ml Lactobacillus rhamnosus. Results showed that treatments containing higher concentrations of maltodextrin had more survival rate during storage, however survival rate of Lactobacillus rhamnosus was higher than Lactobacillus acidophillus during storage period. Acidity (dornic) was increased during 10 days of storage period. Sensory evaluation showed control sample and T2 samples had highest score and acceptability among all treatments, however, on the basis of obtained results, T2 was the highest similarity to control sample and was the best among other treatments.

Lead is one of the most toxic heavy metals for the human health. So researchers are always trying to remove of lead from the environment. Recently it was proved that probiotics by binding to heavy metals remove them from the environment. Hence, in the present study, the protective impact of Lactobacillus rhamnosus on hematological factors in rats infected with the lead with a potential to remove lead from the body is evaluated. 32 female rats (130 ± 20 g) were purchased from Pasteur Institute. The animals are randomly divided into 4 groups. A: control group, B: exposed to lead, C: Lactobacillus rhamnosus treatment, D: exposed to lead and Lactobacillus rhamnosus. After completion of the treatment period (8 weeks), blood parameters and the concentration of zinc protoporphyrine in the blood were measured. Levels of these factors in group D showed no significant change compared to group B. In group B, the number of white blood cells, lymphocytes, platelets and the concentration of zinc protoporphyrine showed a significant increase and the number of red blood cells, hematocrit percentage, hemoglobin concentration and its indices showed a significant decrease relative to the control group while changes of these factors in Group D compared to the control group had a lower level. So probably Lactobacillus rhamnosus was able to bind to lead and by its excretion from intestines, prevented from entry of excess lead into the blood. Therefore, the harmful effects of lead on blood factors have reduced.

Probiotics are food supplements and pharmaceutical substances prepared from living microorganisms that with enhancement of microbial equilibrium of intestinal microbiota, insert useful effects on the host (human/animal). Nutrients could affect the brain and neurohormones via vagus nerve. Therefore, probiotics can regulate some parts of brain activities and effect in better function. The aim of this study was examination of Lactobacillus rhamnosus, the native Iranian probiotic isolated from Tarkhineh dough (a carbonated yoghurt drink) product on the rat passive avoidance. We used 56 male Wistar rats with 250-300 gr weight range. For induced amnesia intra peritoneal pre-training injection ethanol and for one mount administrated with1×10 9 CFU/ml of with or without probiotic bacteria. We used the step-through passive avoidance to examine long-term memory in male Wistar rats. Post-training subcortical (SC) administration of ethanol (1 mg/kg) induced amnesia. This amnesia was reversed in probiotic receiving groups. L. rhamnosus isolated from Tarkhineh dough, enhanced the passive avoidance learning of male Wistar rats that received ethanol. Our data demonstrated the positive effect of this probiotic on learning and memory.

Dental caries, caused mainly by mutans Streptococci, is the most common chronic disease in the world. Employment of probiotics is a new emerged technique to prevent dental caries production, and Lactobacillus rhamnosus is one of the important common probiotics in this strategy. This study aimed to evaluate the effects of L. rhamnosus on the adhesion of oral Streptococci. This cross-sectional study was carried out on 40 isolates of mutans and non-mutans Streptococci isolated from dental plaque and caries of the volunteers who admitted in dental school of Islamic Azad University, Khorasgan. The biofilm formation ability of these strains was investigated and the strongest isolates in this term were selected. The effect of L. rhamnosus (ATCC4769) on the adhesion of Streptococci was investigated by several methods; 1: an equal volum of Lactobacillus and Streptococcus, 2: application of Lactobacilli 30 minutes before induction of Streptococci into the system, 3: probiotic pellet 4: a supernatant of the overnight culture of probiotic. Overall, L. rhamnousus led to reduction of Streptococci adhesion to surface using all four strategies. The second method was the most effective, its effect was more efficient on S. mutans adhesion than non-mutans. There was no significant difference between third and fourth methods, but effect of both methods on S. mutans was more than other Streptococci. Application of L. rhamnousus as probiotic could reduce the adhesion of mutans and non-mutans Streptococci to dental surfaces and therefore can reduce dental decay.