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Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms
BACKGROUND: Cadmium is a non-essential metal that is toxic because of its interference with essential metals such as iron, calcium and zinc causing numerous detrimental metabolic and cellular effects. The amount of this metal in the environment has increased dramatically since the advent of the indu...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3750252/ https://www.ncbi.nlm.nih.gov/pubmed/23855952 http://dx.doi.org/10.1186/1471-2180-13-161 |
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author | Edwards, Chad D Beatty, Joseph C Loiselle, Jacqueline BR Vlassov, Katya A Lefebvre, Daniel D |
author_facet | Edwards, Chad D Beatty, Joseph C Loiselle, Jacqueline BR Vlassov, Katya A Lefebvre, Daniel D |
author_sort | Edwards, Chad D |
collection | PubMed |
description | BACKGROUND: Cadmium is a non-essential metal that is toxic because of its interference with essential metals such as iron, calcium and zinc causing numerous detrimental metabolic and cellular effects. The amount of this metal in the environment has increased dramatically since the advent of the industrial age as a result of mining activities, the use of fertilizers and sewage sludge in farming, and discharges from manufacturing activities. The metal bioremediation utility of phototrophic microbes has been demonstrated through their ability to detoxify Hg(II) into HgS under aerobic conditions. Metal sulfides are generally very insoluble and therefore, biologically unavailable. RESULTS: When Cd(II) was exposed to cells it was bioconverted into CdS by the green alga Chlamydomonas reinhardtii, the red alga Cyanidioschyzon merolae, and the cyanobacterium, Synechoccocus leopoliensis. Supplementation of the two eukaryotic algae with extra sulfate, but not sulfite or cysteine, increased their cadmium tolerances as well as their abilities to produce CdS, indicating an involvement of sulfate assimilation in the detoxification process. However, the combined activities of extracted serine acetyl-transferase (SAT) and O-acetylserine(thiol)lyase (OASTL) used to monitor sulfate assimilation, was not significantly elevated during cell treatments that favored sulfide biosynthesis. It is possible that the prolonged incubation of the experiments occurring over two days could have compensated for the low rates of sulfate assimilation. This was also the case for S. leopoliensis where sulfite and cysteine as well as sulfate supplementation enhanced CdS synthesis. In general, conditions that increased cadmium sulfide production also resulted in elevated cysteine desulfhydrase activities, strongly suggesting that cysteine is the direct source of sulfur for CdS synthesis. CONCLUSIONS: Cadmium(II) tolerance and CdS formation were significantly enhanced by sulfate supplementation, thus indicating that algae and cyanobacteria can produce CdS in a manner similar to that of HgS. Significant increases in sulfate assimilation as measured by SAT-OASTL activity were not detected. However, the enhanced activity of cysteine desulfhydrase indicates that it is instrumental in the provision of H(2)S for aerobic CdS biosynthesis. |
format | Online Article Text |
id | pubmed-3750252 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-37502522013-08-24 Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms Edwards, Chad D Beatty, Joseph C Loiselle, Jacqueline BR Vlassov, Katya A Lefebvre, Daniel D BMC Microbiol Research Article BACKGROUND: Cadmium is a non-essential metal that is toxic because of its interference with essential metals such as iron, calcium and zinc causing numerous detrimental metabolic and cellular effects. The amount of this metal in the environment has increased dramatically since the advent of the industrial age as a result of mining activities, the use of fertilizers and sewage sludge in farming, and discharges from manufacturing activities. The metal bioremediation utility of phototrophic microbes has been demonstrated through their ability to detoxify Hg(II) into HgS under aerobic conditions. Metal sulfides are generally very insoluble and therefore, biologically unavailable. RESULTS: When Cd(II) was exposed to cells it was bioconverted into CdS by the green alga Chlamydomonas reinhardtii, the red alga Cyanidioschyzon merolae, and the cyanobacterium, Synechoccocus leopoliensis. Supplementation of the two eukaryotic algae with extra sulfate, but not sulfite or cysteine, increased their cadmium tolerances as well as their abilities to produce CdS, indicating an involvement of sulfate assimilation in the detoxification process. However, the combined activities of extracted serine acetyl-transferase (SAT) and O-acetylserine(thiol)lyase (OASTL) used to monitor sulfate assimilation, was not significantly elevated during cell treatments that favored sulfide biosynthesis. It is possible that the prolonged incubation of the experiments occurring over two days could have compensated for the low rates of sulfate assimilation. This was also the case for S. leopoliensis where sulfite and cysteine as well as sulfate supplementation enhanced CdS synthesis. In general, conditions that increased cadmium sulfide production also resulted in elevated cysteine desulfhydrase activities, strongly suggesting that cysteine is the direct source of sulfur for CdS synthesis. CONCLUSIONS: Cadmium(II) tolerance and CdS formation were significantly enhanced by sulfate supplementation, thus indicating that algae and cyanobacteria can produce CdS in a manner similar to that of HgS. Significant increases in sulfate assimilation as measured by SAT-OASTL activity were not detected. However, the enhanced activity of cysteine desulfhydrase indicates that it is instrumental in the provision of H(2)S for aerobic CdS biosynthesis. BioMed Central 2013-07-15 /pmc/articles/PMC3750252/ /pubmed/23855952 http://dx.doi.org/10.1186/1471-2180-13-161 Text en Copyright © 2013 Edwards et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Edwards, Chad D Beatty, Joseph C Loiselle, Jacqueline BR Vlassov, Katya A Lefebvre, Daniel D Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
title | Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
title_full | Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
title_fullStr | Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
title_full_unstemmed | Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
title_short | Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
title_sort | aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3750252/ https://www.ncbi.nlm.nih.gov/pubmed/23855952 http://dx.doi.org/10.1186/1471-2180-13-161 |
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