JOURNAL OF MICROBIAL WORLD
Year:2010 | Volume:3 | Issue:2 (7)|Papers Count:9

Background and objectives: L-Asparaginase (isozyme II) is a natural product of E. coli that possesses an antitumor activity. This enzymeis used for treating acute lymphoblastic leukemia (ALL). The aim of this study was to clone of the corresponding gene without signal peptide and also without first methionine as well as to express the gene in cytoplasm.Materials and Methods: The L-Asparaginase gene was isolated by PCR from E. coli K12 strain and cloned into engineered expression vector pET32. Sequencing and evaluation of gene expression were done by routine procedure. Methionine amino peptidase containing recombinant plasmid was purified and transferred into recombinant asparaginase producing bacterium by heat shock method.Results: The majority of L-asparaginase was expressed in cytoplasm. Based on high expression of methionine amino peptidase enzyme in E. coli Origami, it was expected that the first methionine of L-asparaginase has been removed efficiently.Conclusion: According to the achieved results, the recombinant bacterium with extensive ability to express cytoplasmic recombinant L-asparaginase is an ideal candidate for industrial production of L-asparaginase.

Background and Objective: Brucellosis is a zoonotic disease caused by Brucella bacteria. According to recent studies, antimicrobial activity of silver nanoparticle was approved. The aim of this study was to investigate the antimicrobial activity of Doxycycline - silver nanoparticles conjugate against Brucella meltensis 16M.Material and Methods: After preparing the doxycycline-silver nanoparticle conjugate, its antimicrobial activity against Brucella meltensis 16M was determined by Well Diffusion Agar method in Muller Hintone Agar media. Also, Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Doxycycline-silver nanoparticle conjugate was determined by Macrodilution method in Muller Hintone Broth media. Finally, antibacterial effect of the nanoparticle was assayed in animal model.Results: The results showed that Doxycycline-silver nanoparticle conjugate has antimicrobial activity against Brucella melitensis 16M in laboratory condition. In mouse model, the conjugate of Doxycycline-silver nanoparticle could decrease effectively the Brucella melitensis load in liver.Conclusion: This study demonstrated that Doxycycline-silver nanoparticle conjugate has synergistic effect on Brucella melitensis 16M and can be useful in treatment of brucellosis.

Background and Objective: Recently the presence of several urease-positive bacteria other than Helicobacter pylori has been reported in gastric ulcer patients. The purpose of this study was the isolation and identification of urease-positive bacteria other than Helicobacter pylori in patients with gastric ulcer and at the same time, determining the anti-microbial effects of silver nanoparticles on the isolated bacteria.Materials and Methods: 50 gastric antrum biopsies were collected from patients with gastric ulcer who were admitted to the Rasoul Akram hospital (Tehran) by gastrointestinal specialists. The samples were transferred to the microbiology laboratory by transitive liquid medium. Urease-positive bacteria in the stomach were identified by standard bacteriological methods, including culture-specific and biochemical tests. The antimicrobial effects of the silver nanoparticles on urease-positive bacteria were determined according to minimum inhibitory concentration (MIC) and Minimum bactericidal Concentration (MBC) techniques.Results: The results showed that 42% of collected samples was urease-positive (10% Klebsiella pneumoniae, 10% Staphylococcus aureus, 8% Enterobacter cloace, 6% Enterobacter aglomerans, 4% Klebsiella azaene and 4%Citrobacter frondi). The antimicrobial effects of silver nanoparticles on the isolated bacteria showed 1.56-12.5 MIC and 3.125-25 MBC.Conclusion: Growth of urease-positive bacteria may lead to false positive observation on UBT and rapid urease tests. Therefore, it is better all urease-positive bacteria isolated from stomach to be sent for accurate diagnosis in order to improve the impacts of treatment. Also, in order to avoiding of bacterial resistance to antibiotics, silver nanoparticles are appropriate alternatives.

Background and Objective: Tuberculosis is one of important cause of death in several countries. Mycobacterium tuberculosis complex is consisted of homogenous slow growing mycobacteria that their isolation and identification are difficult and time consuming. The objective of this study was to evaluate a molecular method for differentiation of Mycobacterium tuberculosis from Mycobacterium bovis, and at the same time, to compare the method with biochemical tests.Material and methods: In this study 68 sputum specimens were collected from the smear positive patients who hospitalized in health centers of Markazi province. The samples were cultivated in the specialized cultures. Also, 10 isolates of Mycobacterium bovis that were obtained from different area of Iran as well as 6 standard strains have been used for comparison. After performance of biochemical tests, oxyR pseudogene was amplified by PCR and the PCR products were digested by AluI endonuclease.Results: The digestion on PCR products of Mycobacterium tuberculosis and Mycobacterium bovis showed one and three fragment panel, respectively, on the gele. Only one isolate of human Mycobacterium bovis strain has been identified. The results of PCR-RFLP were consistent with biochemical tests.Conclusion: Since PCR-RFLP is a rapid and accurate method for differentiation between Mycobacterium bovis and other Mycobacterium tuberculosis complex and the results are important in terms of diagnosis and treatment of tuberculosis.

Background and Objective: The visceral leishmaniosis is a common disease between human and animal caused by Leishmania infantum. The main resource of this disease is canidae family. This study was conducted to determine the genus and species of the parasites that cause visceral leishmaniosis in Boyer Ahmad City.Materials and Methods: In this study, the smears were prepared from spleen and liver extracts of 15 dogs in Boyerahmad city that were suspected to visceral leishmaniosis according to clinical signs (2010). Also some of the samples were evaluated by Nested-PCR to determine the geneus and species of the parasite.Results: According to the smear observation and Nested-PCR results, 14 cases (93.3%) and one case (6.7%) of the samples have been detected as Leishmania infantum and Leishmania major, respectively.Conclusion: The molecular results showed that the main etiological agent of visceral leishmaniosis in the animal reservoir (dogs) of Boyer Ahmad Township is Leishmania infantum. However, Leishmania major also was detected as one of the causes of visceral leishmaniosisin in the region.

Background and Objective: The extensive increasing antibiotic resistance in the world made us use natural probiotic compounds as a curing alternative.In this study two lactobaclilli (L. casei and L. acidophilus), which in another survey were determined as the most active probiotics for removing and eliminating cholesterol, were chosen to evaluate their antibacterial activity against pathogens.Material and Methods: This case control study had performed on the Lactobacillus isolated strains from the Fars local dairy products. The resistance of the lactobacillus strains to antibiotics was assessed using disk diffusion method. Also, in order to evaluate their ability to inhibite the growth of other pathogens, the obtained supernatant of their 72 hours broth culture have been used by agar diffusion method in both active and inactive condition.Results: Although L. casei was resistant to all assayed antibiotics, L. acidophilus was susceptible to tobramycin and vancomycin. Also, the antibacterial studies of the Lactobacilli on several pathogens showed an inhibition zone for most of the assayed pathogens except for B. subtilis.Conclusion: According to the resistance of these two lactobacilli to the ordinary antibiotics and their high antibacterial activities against the nosocomial infections, they are applicable for probiotics purposes.

Background and objective: In this study, the antifungal effects of the extracted oil of Petroselinum crispum, Acimum basilicum, Anethum graveolens, Mentha viridis on Aspergilus parasiticus ATCC 15517 was evaluated. Also, the chemical compositions of the vegetables were determined.Materials and methods: The essential oils were obtained using hydrodestillation of dried plant material. Their compositions and Minimum inhibitory concenteration (MIC) were determined by GC-MS and serial dilution method, respectively.Results: The main component of the essential oils was detected as follow: Mentha viridis: Benzen bromophenoxy-methyl dimethyl, Acimum basilicum: Ethyldecaborane, Anethum graveolens: Decarbadecaborane- dimethyl and Petroselinum crispum: Methyl anthracene. Minimum Inhibitory concenteration of the essential oils determined by serial dilution method. MIC for Mentha viridis, Anethum graveolens, Acimum basilicum, Petroselinum crispum were 1.5, 1.5, 3 and 4 ml/ml, respectively. The antifungal power of assayed essential oils was different, depending on their concentration. This effect in Mentha viridis and Anethum graveolens was identical and stronger than two others.Conclusion: These results indicate that the mentioned essential oils had great antifungal activities and could be used as preservatives and fungicides in food in order to preventing of food pollution.

Background and Objective: Stem rot disease caused by Magnaporthe salvinii is one of the most common limiting factors for rice production. It was first reported from Italy and in a short time from all over the world. Although rice stem rot in tillering stage was identified widely in different area of Fars province, no causal agents had been detected before the study. The aim of this study was to evaluate the causal agent of rice foot rot specially Magnaporthe salvinii in Fars province.Materials and methods: During 2008-2009, foot and root rotted rice samples were collected from infected fields in Fars province. After purification of the Samples and their cultivation in selective media, the produced fungal sexual forms were characterized. In the next step, all of the isolates were tested for pathogenicity.Results: The cultured isolates first produced white colonies in culture media, but their color changed to gray after few days. Based on our results, the asexual and sexual forms were diagnosed as Nakataea sigmoidea and Magnaporthe salvinii, respectively. Pathogenicity tests showed that the isolate is very virulent and It can make injuries in the susceptible hosts.Conclusion: The result obtained from this study showed that rice foot and root rot caused by Magnaporthe salvinii is very dispersed in various aria of Fars province. This is the first report of Magnaporthe salvinii in Fars province.