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چکیده
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Background and Aim: Much attention has been given to approaches for removing selenitecontaining contaminates from toxic sites. Microbial bioremediation has emerged as a green technology for selenium treatment in the environment. The aim of this research was to develop methods to study the capability of isolated yeast strains to detoxify selenite by a bioremediation process under resting cell conditions. Methods: Toxicity of selenite towards the resistant isolated yeasts was determined by determining Minimal Inhibitory Concentrations (MICs), experiments of zone of growth inhibition and growth curves. The isolated yeast strains were characterized based on amplification the ITS1 5.8S ITS2 rDNA sequences. A colorimetric method using 3, 3- Diaminobenzidine hydrochloride has been developed for the microbial selenite removal. Results: In this study, we isolated 43 selenite-resistant yeasts from samples collected from industrial wastewaters. The toxicity experiments showed that selenite had a MIC of 18 g/l for isolate se29w, 14 g/l for se18w and 11 g/l for se19w. These strains were identified as Candida spp., Pichia spp. and Saccharomyces spp., respectively. Based on the results of selenite removal experiments, the resting cells of Candida sp. strain se29w is capable remove 92.5% of selenite with initial concentration of 1 g/l. Conclusion: This research evaluated the potential of native yeast strains for bioremediation of toxic selenite. These isolates display high-level of selenite resistance and a high level of selenite removal which might be interesting for selenium treatment in the environment.
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