Isolation of arsenic accumulating bacteria from garbage leachates for possible application in bioremediation.

BACKGROUND AND OBJECTIVES: Bioremediation is a process to reduce toxic heavy-metals, such as arsenic, in the environment using microorganisms. This study aimed to isolate arsenic remediating microbial strains from garbage leachates and to evaluate the effects of several factors on bioremediation by isolated strains. MATERIALS AND METHODS: After isolating arsenic-resistant bacteria from garbage leachates and determining their MIC values, Taguchi design of experiments was used to evaluate the effect of arsenic concentration, pH solution, temperature, and contact time on arsenic bioremediation by isolated bacteria. RESULTS: The results revealed that 3 arsenic-resistant strains of genus Bacillus characterized as KL1, KL4, and KL6 had arsenic bioremediation activity. Based on the results, the highest bioremediation of arsenic by Bacillus sp. KL1 was obtained as 77% after 24 hours at 40°C, pH 5, and 150 ppm concentration. However, the maximum bioremediation of arsenic by KL4 (91.66%) and KL6 (88%) was achieved after 24 hours at 40°C, pH 5, and 60 ppm concentration and at 35°C, 90 ppm concentration, pH 5 after 36 hours, respectively. CONCLUSION: The results presented here may facilitate improvements in the eliminating arsenic from contaminated sites and reducing environmental pollutions.

In Silico Design of a Chimeric Protein Containing Antigenic Fragments of Helicobacter pylori; A Bioinformatic Approach.

Helicobacter pylori is a global health problem which has encouraged scientists to find new ways to diagnose, immunize and eradicate the H. pylori infection. In silico studies are a promising approach to design new chimeric antigen having the immunogenic potential of several antigens. In order to obtain such benefit in H. pylori vaccine study, a chimeric gene containing four fragments of FliD sequence (1-600 bp), UreB (327-334 bp),VacA (744-805 bp) and CagL(51-100 bp) which have a high density of B- and T-cell epitopes was designed. The secondary and tertiary structures of the chimeric protein and other properties such as stability, solubility and antigenicity were analyzed. The in silico results showed that after optimizing for the purpose of expression in Escherichia coli BL21, the solubility and antigenicity of the construct fragments were highly retained. Most regions of the chimeric protein were found to have a high antigenic propensity and surface accessibility. These results would be useful in animal model application and accounted for the development of an epitope-based vaccine against the H. pylori.

Cloning, expression and purification of Pwo polymerase from Pyrococcus woesei.

BACKGROUND AND OBJECTIVES: Pyrococcus woesei is a hyperthermophilic archaea and produces a heat stable polymerase (Pwo polymerase) that has proofreading activity. MATERIALS AND METHODS: In this study, this microorganism was cultured, its DNA was extracted and the pwo gene polymerase was cloned, expressed and purified. The DNA sequence of the cloned gene was verified by sequencing. The pwo polymerase gene consists of 2,328 bps (775 amino acids with about 90 kD molecular weight). Cloning was done by GATEWAY™ Cloning System and for purification of recombinant protein; His6x-Tag was added to the C-terminus of the recombinant protein. RESULTS AND CONCLUSION: We could purify Pwo polymerase enzyme by Ni-NTA resin. PCR assay showed that Pwo polymerase activity is comparable to a commercial Pfu polymerase activity.