BIOLOGICAL JOURNAL OF MICROORGANISM
Year:2019 | Volume:8 | Issue:29 |Papers Count:7

Introduction: The energy crisis is an urgent issue due to the increased consumption of fossil fuels. Therefor alternative energy sources are, of critical importance. Sediment Microbial fuel cells (SMFCs) are more important among other renewable energy sources in which chemical energy in organic compounds is converted to electrical energy due to proper bacteria (exoelectrogens) catalytic activity. Materials and methods: In this study, one liter glassy reactor was used, half of it was filled with Urmia lake sediment, where microbial consortium are present, as anodic part and upper half was filled with lake water as cathodic part. Copper wires attached to graphite electrodes 4×4 cm² (choice electrode) and via an external resistance 2/2 kΩ two sections related to each other. Electrochemical performance was evaluated by a digital voltimeter. The effectiveness of methyl red as mediator and lactate after determination of optimum concentration which is added every 15 days was evaluated. All fuel cells were studied for over 45 days of experiment. Results: The results demonstrated the mediator SMFC with power density of 7/54 mW/m² has a distinct difference with mediator-less SMFC with power density of 0. 46 mW/m² . The recorded power density of SMFC with lactate and mediator was 4/44 ± 1/44 mW/m² . Discussion and conclusion: Sediment microbial consortia degrade available organic compounds and transfer to the anode electrode by using synthetic mediators. The results showed, in addition to external synthetic mediator, methyl red increases fuel cell electrochemical performance. While it was expected that fuel cell performs well in the presence of mediator and external carbon source, we witnessed better electrochemical performance in the absence of lactate.

Introduction: Considering increasing concern about the resistance of microbial infections to antibiotics and nisin peptide reducing effect (AMP) due to resistance growth in bacterial strains; extensive researches were implemented based on nanotechnology. The aim of current research was to investigate synergistic effect of silver nanoparticles conjugated with nisin on genome of Escherichia coli as a gram negative bacteria model. Materials and methods: After culturing the bacteria in a Nutrient Broth medium; treatments were performed at concentrations of 50, 75, 100, 125 μ g/ml of silver nanoparticles; concentrations of 25, 50, 75, 100, 150, 200μ g/ml of nisin and concentrations of 30, 50, 75 μ g/ml of silver nanoparticles conjugated with nisin solution. After reading the optical density at 600 nm of control samples and treated at concentrations of 50 and 75 μ g/ml of silver nanoparticles; 50 and 75 μ g/ml of nisin, 50 and 75 μ g/ml of silver nanoparticles conjugated with nisin, DNA was extracted and RAPD-PCR was used to investigate genomic effect. Analysis of the results of RAPD-PCR was performed by NTSYS-PC software based on Dice coefficient to calculate the similarity matrix and UPGMA. Results: The results showed that the growth inhibitory effect of silver nanoparticles conjugated with nisin was higher than of individual application of nisin and silvernanoparticles and the genomic effect of the above mentioned conjugates was higher and lower than nisin and silver nanoparticles, respectively. Therefore, the mentioned conjugated nanoparticles and nisin had no synergistic effect on the bacterial genome. Discussion and conclusion: These conjugated nanoparticles with nisin can be used as proper and strong antibacterial with the least genomic and mutation effect.

Introduction: Nowadays, climate changes and wide usage of chemical insecticides cause the emergence of Anopheles mosquito resistant species and environmental hazards. Therefore, biocontrol as an alternative approach provides the vivid outlook for combating these risks. Hereupon, the special attention is paid to insecticides bacteria especially Bacillus thuringiensis and protein derived from it as Cry toxins. However, scrutinizing the structural and functional characteristics of these toxins have not been much attended, so it is aimed in this study by in silico investigations. Materials and methods: For this purpose Cry4, Cry11, Cry19, Cry24 and Cry39 protein sequences were extracted from NCBI database, monitoring structural and functional, physicochemical, topological features, prediction of secondary and three-dimensional modelling were carried out with programs like Interproscan, Protparam, TMHMM, Psipred and modeller9. 15. Finally, their binding affinity with relevant receptors was assessed by PatchDock molecular docking program. Results: The results indicate various features of physicochemical, non-secretory and toxin accumulation. Functional monitoring has traced domains with similar functions of other Cry toxin family members. Secondary structure prediction shows the existence of helixes and sheets in similar distribution pattern with each other. In addition, the design and quality evaluation of 3D structure of all toxins were obtained in desirable level. The binding affinity assessment represents stronger binding of Cry11 and Cry24 to most of the receptors. Discussion and conclusion: In general, the results of this study, in addition to provision functional data related to Cry toxin, provide optimum practical model of capable toxins production based on multimodal protein design for biocontrol of Malaria mosquitos.

Introduction: Soil contamination to heavy metals such as lead and zinc in and around mines causes a change in structure, complexity, diversity and activity of soil microbial communities like bacteria. Materials and methods: In the present research, PCR-DGGE approach was used to investigate the effects of Pb and Zn-contamination in Bama mine near Isfahan city on bacterial diversity, structure and complexity. Basal Respiration (BR) and Substrate Induced Respiration (SIR) was also used to assess microbial activities. Nine samples from three locations (3 for each) with different levels of heavy metal contamination were taken (from low to high), then their DNA were directly extracted. Also a 468 base pair of their 16S rRNA genes were amplified using specific primers, and their fingerprints were obtained by denaturing gradient gel electrophoresis (DGGE). BR and SIR were measured, and metabolic quotient was calculated. Finally, soil microbial activity in polluted conditions was achieved. Results: Our findings illustrate that heavy metal contamination has negative effects on bacterial diversity. By increasing the bioavailability of Pb and Zn, the complexity and diversity of bacterial communities decreased and the frequency of resistant bacteria increased. By increasing Pb and Cd contamination, SIR reduced and this shows the reduction in microbial biomass. In these conditions, SIR and metabolic quotient was more sensitive than BR, so they are better ecological indicators in polluted soils. Discussion and conclusion: Although bacterial diversity showed reduction in polluted soils, diversity is still relatively high. Bacterial ability to adapt in heavy metal contamination, bacterial resistance and their important functional roles in such conditions are valuable in soil ecosystem suggesting further researches on them.

Introduction: Mycoplasma genitalium is a vaginosis pathogen bacterium to which conventional clinical microbiology techniques cannot be applied due to difficulties in cultivation and slow growth incubation. The aim of this study was to detect the frequency of this bacteria among vaginosis infected women and compare it with healthy individuals using PCR and culture methods. Materials and Methods: For this purpose, we conducted a study among 150 patients with bacterial vaginosis and compared the frequency with 45 healthy women with no vaginal infections collected from Imam Zaman Hospital, Robat karim city in May up to September, 1392 (2013). To detect the cases infected with Mycoplasma genitalium, we used culture technique and Polymerase Chain Reaction (PCR) as well. Then, the sensitivity and specificity were calculated. The data was analyzed using the computer software SPSS for windows (version 19), using Cross Tab and Chi square. P<0. 05 was considered statistically significant. Results: The results indicated that among the infected cases, 107 )%71. 8) samples were positive using PCR but only 73(49. 3) of samples were growing in culture. The sensitivity for culture method was reported to be 49% only while, using PCR method came to 71%. In healthy individuals, 100% of samples were negative in culture which shows specify of 100% of this technique. The specificity of PCR method was 89%. Discussion and conclusion: The findings showed that PCR is a more reliable technique to detect Mycoplasma genitalium compared to culturing method. It is also suggested that presence of this organism is strongly associated with bacterial vaginosis in female.

Introduction: Nowadays, concrete has been widely used as one of the best and most practical building materials in various types of structures. Concrete permeability is a factor that reduces its stability and decreases the service life of concrete structures. This study has been conducted with the aim of finding bacteria able to repair concrete surface in order to reduce its permeability. Materials and Methods: Isolated bacteria from alkaline soils of north and center of Iran were subjected to primary and secondary screening for producing urease enzyme and calcium carbonate precipitation. Selected isolates were cultured in specific broth medium for calcium carbonate precipitation. Then, the rate of their growth and calcium carbonate production were compared. Produced calcium carbonate, by the premier isolate, was verified using XRD. The ability of this isolate was evaluated in the repair of the concrete surface porosity and the reduction of its permeability by Scanning Electron Microscopy (SEM). Results: The results of primary and secondary screening showed that Bacillus sp. UTMC 2623 produces the highest amount of calcium carbonate precipitation (8. 8 g/L) in three days. Its XRD analysis confirmed the presence of crystalline calcium carbonate in dried bacterial precipitate. SEM analysis showed that this bacterium creates the best coating on the concrete surface along with the calcium source. Discussion and conclusion: The present study is a report on the repairing activity of Bacillus sp. UTMC 2623 which can be used to find other native and promising microorganisms in concrete surface repair.

Introduction: Thermophilic proteases can be used in various industries, including detergents, pharmaceuticals, food, etc. These enzymes are produced by thermophilic microorganisms, including bacteria. Materials and methods: Sampling was carried out from Dehloran hot springs in Ilam province in the west of Iran to find new protease producing bacteria. Then, the effect of pH, temperature and finally the effect of different heating time on the production of protease enzyme were evaluated. Then, Polymerase Chain Reaction (PCR) was performed to detect the strain. Protease was purified through anion exchange using DEAE-sepharose column and its molecular weight was estimated using SDS-PAGE technique. Then, activity and stability of the enzyme were investigated in temperature and pH range. Results: Among isolated strains, bacteria Bacillus sp. DEM07 (registered in the World Gene Bank with access number KY392988) with the highest diameter of the protease clear zone, was selected to produce thermo tolerant alkaline protease. The maximum production of the alkaline protease enzyme was observed at 50 ° C, pH 7 and 48 hours after culture. The protease enzyme was purified by anionic chromatography and its molecular weight was estimated to be about 27. 5 kDa after purification. The enzyme was active and stable at the temperature range of 30 to 55 ° C and the optimum temperature of the enzyme activity was observed at 50 ° C. The pH range for activity and its stability was from 4 to 11, and the optimum activity of the enzyme was observed at pH 10. Discussion and conclusion: In this study, the protease enzyme purified from Bacillus sp. DEM07 is a thermo tolerant alkalophilic protease. On the other hand, by creating the optimal conditions for achieving high production of thermo-tolerant alkalophilic protease, this enzyme has a high potential for use in various industries.