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Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres

BACKGROUND: Selenium and Tellurium have many common chemical properties as both belong to group 16 of the periodic table. High toxicities of Se and Te oxyanions cause environmental problems in contaminated soils and waters. Three strains (C4, C6 and C7) of selenite reducing and nanoparticle forming...

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Autores principales: Bajaj, Mini, Winter, Josef
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4254260/
https://www.ncbi.nlm.nih.gov/pubmed/25425453
http://dx.doi.org/10.1186/s12934-014-0168-2
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author Bajaj, Mini
Winter, Josef
author_facet Bajaj, Mini
Winter, Josef
author_sort Bajaj, Mini
collection PubMed
description BACKGROUND: Selenium and Tellurium have many common chemical properties as both belong to group 16 of the periodic table. High toxicities of Se and Te oxyanions cause environmental problems in contaminated soils and waters. Three strains (C4, C6 and C7) of selenite reducing and nanoparticle forming aerobic bacteria which were isolated from agricultural soils of India containing high concentrations of Se were investigated after 3.5 months of freeze-storage for their resistance against the toxic oxyanion tellurite and its reduction to non toxic elemental form Te(0) as well as nanoparticles formation. RESULTS: Strains C4, C6 and C7 reduced tellurite at maximum reduction rates of 2.3, 1.5 and 2.1 mg Te (IV)/L/d, respectively and produced extracellular Te(0) nanospheres as revealed from SEM-EDX analysis. Production of extracellular Te nanospheres has been described seldom. Further, concurrent reduction of both selenite and tellurite by bacteria was examined as these toxic oxyanions are often present together in natural environments, mine tailings or wastewater from copper refining. Interestingly, bioreduction of 100 mg/L selenite in shake flasks was not much affected by the presence of 10 mg/L tellurite but tellurite reduction rate increased 13 fold with selenite in the medium. The concurrent reduction of these oxyanions resulted in rarely described bioformation of extracellular nanoparticles composed of both Se and Te, reported first time for aerobically growing heterotrophic non-halophilic bacterial cultures. Duganella violacienigra, the closely related strain to C4 was also found to be resistant to oxyanions of Se and Te. CONCLUSIONS: Selenite reducing heterotrophic non-halophilic aerobic bacteria revived from 3.5 months freeze storage could successfully reduce toxic tellurite to non toxic elemental form and produced extracellular nanospheres during detoxification. Presence of relatively less toxic selenite in the medium triggers bioreduction of more toxic tellurite leading to formation of extracellular SeTe nanospheres which are sought by solar and optical recording media industry because of their excellent photovoltaic and optical properties. The bacterial cultures investigated in this study could be exploited commercially to remediate not only selenite and tellurite-contaminated soil and water but also for green synthesis of extracellular Se, Te and Se + Te nanospheres.
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spelling pubmed-42542602014-12-04 Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres Bajaj, Mini Winter, Josef Microb Cell Fact Research BACKGROUND: Selenium and Tellurium have many common chemical properties as both belong to group 16 of the periodic table. High toxicities of Se and Te oxyanions cause environmental problems in contaminated soils and waters. Three strains (C4, C6 and C7) of selenite reducing and nanoparticle forming aerobic bacteria which were isolated from agricultural soils of India containing high concentrations of Se were investigated after 3.5 months of freeze-storage for their resistance against the toxic oxyanion tellurite and its reduction to non toxic elemental form Te(0) as well as nanoparticles formation. RESULTS: Strains C4, C6 and C7 reduced tellurite at maximum reduction rates of 2.3, 1.5 and 2.1 mg Te (IV)/L/d, respectively and produced extracellular Te(0) nanospheres as revealed from SEM-EDX analysis. Production of extracellular Te nanospheres has been described seldom. Further, concurrent reduction of both selenite and tellurite by bacteria was examined as these toxic oxyanions are often present together in natural environments, mine tailings or wastewater from copper refining. Interestingly, bioreduction of 100 mg/L selenite in shake flasks was not much affected by the presence of 10 mg/L tellurite but tellurite reduction rate increased 13 fold with selenite in the medium. The concurrent reduction of these oxyanions resulted in rarely described bioformation of extracellular nanoparticles composed of both Se and Te, reported first time for aerobically growing heterotrophic non-halophilic bacterial cultures. Duganella violacienigra, the closely related strain to C4 was also found to be resistant to oxyanions of Se and Te. CONCLUSIONS: Selenite reducing heterotrophic non-halophilic aerobic bacteria revived from 3.5 months freeze storage could successfully reduce toxic tellurite to non toxic elemental form and produced extracellular nanospheres during detoxification. Presence of relatively less toxic selenite in the medium triggers bioreduction of more toxic tellurite leading to formation of extracellular SeTe nanospheres which are sought by solar and optical recording media industry because of their excellent photovoltaic and optical properties. The bacterial cultures investigated in this study could be exploited commercially to remediate not only selenite and tellurite-contaminated soil and water but also for green synthesis of extracellular Se, Te and Se + Te nanospheres. BioMed Central 2014-11-26 /pmc/articles/PMC4254260/ /pubmed/25425453 http://dx.doi.org/10.1186/s12934-014-0168-2 Text en © Bajaj and Winter; licensee BioMed Central Ltd. 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Bajaj, Mini
Winter, Josef
Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres
title Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres
title_full Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres
title_fullStr Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres
title_full_unstemmed Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres
title_short Se (IV) triggers faster Te (IV) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres
title_sort se (iv) triggers faster te (iv) reduction by soil isolates of heterotrophic aerobic bacteria: formation of extracellular sete nanospheres
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4254260/
https://www.ncbi.nlm.nih.gov/pubmed/25425453
http://dx.doi.org/10.1186/s12934-014-0168-2
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