فصلنامه زیست شناسی میکروارگانیسم ها
پیاپی 3 (پاییز 1391)

Inability of probiotic bacteria for stable colonization and dominance in intestinal microbiota of aquatic animals، combination of administration with proper prebiotics (Synbiotic) as substrate for increasing growth and stable domination have been suggested. The aim of the present study was determination of the best synbiotic between a probiotic bacteria، P. acidilactici and prebiotics، inulin، oligofructose and xylooligosaccharide. Materials and method s: P. acidilactici was cultured in media containing inulin، oligofructose and xylooligosaccharide as prebiotic. Growth of bacteria and final pH of media were determined in each treatment under anaerobic culture. In addition، short chain fatty acids (Butyric، Propionic and Acetic acid) productions in synbiotic treatments were measured using High Performance Liquid Chromatography (HPLC) system.

Our results revealed that bacteria growth in P. acidilactici with XOS treatments was significantly higher compared to the other synbiotics and to the control groups (P < 0. 05). There were no significant differences between other treatments regarding bacteria growth (P > 0. 05). Moreover، final pH of media in P. acidilactici with XOS group was significantly lower when compared to the other treatments (P < 0. 05). The highest and lowest SCFA produced in all synbiotic treatments were propionic and acetic acid، respectively. While acetic and propionic production showed no significant variation between treatments (P > 0. 05)، the highest production of butyric acid was observed in P. acidilactici with XOS treatment (P < 0. 05). Discussion and

The results of this study confirmed that simultaneous administration of in P. acidilactici and XOS could be a potential optimum synbiotic.

In this study، some molecular methods were designed for rapid detection of resistance to kanamycin and amikacin. Among 120 clinical isolates of mycobacterium tuberculosis، 70 strains were selected for evaluation of possible mutations. A PCR-RFLP method was designed for detection of wild type (using enzyme ajii) and mutant from (BstFNI enzyme) of the isolates. Furthermore، allele specific method (as PCR) was designed for detection mutations in codons 1401 and 1402 gene rrs. Some selected isolates were sequenced. In PCR-RFLP method، among the 70 strains examined by BstFNI enzyme، could detect 17 mutant strains among 24 phenotypicaly resistant and 44 non-mutant isolates from 46 susceptible isolates. The sensitivity of this method was %70. 83 and specificity was %95. 65 on the other hand، 12 mutant from 20 resistant strains and 29 non-mutant strains from 32 susceptible strains were detected by AjiI enzyme. The sensitivity and specificity of this method was 60 and %90. 62، respectively. In MAS PCR، 3 mutants from 6 resistant strains and 12 non-mutants from 17 resistant strains were detected. The sensitivity of this method was 50 and specificity was 70. 58. Results of sequencing method confirmed the results of molecular methods. Discussion and PCR-RFLP method by BstFNI enzyme was the best method for rapid detection of Mycobacterium tuberculosis resistant to second-line injectable drugs and was recommended for routine use.

Heat shock proteins (HSPs) inhibit production of pro- inflammatory cytokines. Carbenoxolone is regarded to induce the production of HSPs. The aim of this study was the evaluation of the effect of Carbenoxolone in reduction of the severity of systemic inflammation induced by LPS in a murine model. %80 lethal dose of LPS was determined in balb/C mice، also appropriate dose of drug for efficient reduction in mortality was determined. LPS+D-GalN with drug were injected to different groups، in different times، after 24 hours the mortality rate was calculated and the severity of necrosis measured in the kidney and livers of the survived mice. After 3 hours serum samples were collected and the concentrations of TNF-α were measured in each group. Administration of Carbenoxolone with LPS reduced the lethality rate from 80 to %20. The severity of necrosis in the liver and kidney of drug administrated groups decreased significantly in comparison with the positive control group. The concentration of TNF-α in mice received LPS increased significantly in comparison with the control group (P=0. 032)، but in drug received groups no significant differences were seen with respect to the control. Discussion and Carbenoxolone significantly reduced the severity and damage due to endotoxic shock.

the use of lactic acid bacteria in fermented dairy products due to their effects participation in flavor، texture and most probiotic properties goes back to centuries ago. Optimal amount of lactic starter culture in the production of lactic acid in the production of cheese and yogurt are used. Isolation of Lactobacillus in MRS medium from various samples was performed. Then، The variation of different characteristics in terms of the ability of Lactobacilli to produce CO2 from glucose، the ability to grow at pH 2. 5 to 8. 5، different concentration of NaCl، 1. 5 to 10. 0 (percent w / v) and temperatures of 15 ° c، 45° c، the ability to move، indole and H2S production were also studied. The production of lactic acid was assayed in skim milk by titration with %1 NaOH. L-lactate isomer was investigated using UK Randox kit. In this study، from 30 samples of different indigenous yoghurt and cheese 43 gram-positive، catalase-negative، oxidase negative lactobacilli were isolated. All isolates were resistant to pH 2. 5 and 30 and %69 of the isolated were sensitive to 7. 5 and %10 concentration of salt respectively. Most of lactic acid production with % 1. 8 and L-lactate 6. 8 g/l were consididered for one isolated. This isolated bacillus based on biochemical tests was identified as Lactobacillus acidophilus. Discussion and The amount of lactic acid production at temperature 37°C was found to be higher than the temperature 25°C criteria that were statistically significant at %1 level. The optimal production of lactic acid in the native isolates and tolerance to appropriate pH and salt tolerance، these properties and studies are provided complementary knowledge to be used in the food industry.

Infertility and abortion can lead to major economic losses. Staphylococcus aureus can cause infertility and abortion. Considering the importance of what was mentioned، present study was conducted to detect S. aureus in bovine infertility and abortion from Shahrekord، Iran. Vaginal discharge from 90 cows with endometritis and 26 aborted cows were investigated to detec S. aureus. Samples were streaked on to Mannitol salt agar plates and incubated at 37°C for 48 hours. Suspected colonies were evaluated to detect S. aureus by biochemical and polymerase chain reaction (PCR) methods. S. aureus was isolated from %5. 5 (5 out of 90) of bovine endometritis and %7. 7 (2 out of 26) of aborted cows. Discussion and The study showed that S. aureus might play a role in bovine infertility and abortion in Shahrekord، but S. aureus could not be considered as the major cause of bovine infertility and abortion in the region.

Owing to the serious environmental problems which have occurred due to the increasing amount of toxic petroleum hydrocarbons in the environment، bioremediation of these compounds by microorganisms seems to be necessary. Among these، toluene is a common pollutant in petrochemical industry and a serious cause for concern due to its adverse health effects and carcinogenic potential. In this study، to isolate toluene-degrading bacteria، contaminated seawater and wastewater samples were collected from the Caspian Sea، the Persian Gulf and municipal wastewater. The best toluene-degrading bacterial strain was biochemically and molecularly characterized and its 16S rDNA sequence was submitted as Bacterium Ex-DG74 (accession no. HQ414235) in NCBI. Then، toluene removal rate، cytochrome P450 enzymatic activity، and growth rate of the isolate on oil and petrochemical contaminants were determined. After enrichment procedures in toluene-containing medium، about twenty toluene-degrading bacteria were isolated. Among them، a newly isolated strain from wastewater exhibited great ability to utilize toluene as the sole source of carbon and energy. According to the results obtained by spectrophotometer and gas chromatograph، Bacterium Ex-DG74 showed a significant tolerance to organic solvent as it could grow in the medium containing %25 (v/v) toluene and also degraded over 70 of %1 (v/v) toluene as the sole source of carbon and energy. Moreover، this bacterium could grow on different toxic oil and petrochemical compounds. Discussion and The results of the present study indicated that cytochrome P450 enzymatic activity can have essential role on biodegradation of different pollutants by Bacterium Ex-DG74. Thus، we suggest this bacterium as a potential biological agent for in situ bioremediation of hydrocarbon-polluted environments.