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1.
Biometals ; 20(6): 853-67, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17273817

RESUMO

The siderophore produced by Rhodococcus rhodochrous strain OFS, rhodobactin, was isolated from iron-deficient cultures and purified by a combination of XAD-7 absorptive/partition resin column and semi-preparative HPLC. The siderophore structure was characterized using 1D and 2D (1)H, (13)C and (15)N NMR techniques (DQFCOSY, TOCSY, NOESY, HSQC and LR-HSQC) and was confirmed using ESI-MS and MS/MS experiments. The structural characterization revealed that the siderophore, rhodobactin, is a mixed ligand hexadentate siderophore with two catecholate and one hydroxamate moieties for iron chelation. We further investigated the effects of Fe concentrations on siderophore production and found that Fe limiting conditions (Fe concentrations from 0.1 microM to 2.0 microM) facilitated siderophore excretion. Our interests lie in the role that siderophores may have in binding metals at mixed contamination sites (containing metals/radionuclides and organics). Given the broad metabolic capacity of this microbe and its Fe scavenging ability, R. rhodochrous OFS may have a competitive advantage over other organisms employed in bioremediation.


Assuntos
Rhodococcus/metabolismo , Sideróforos/química , Ágar/química , Cromatografia Líquida de Alta Pressão/métodos , Epinefrina/análogos & derivados , Epinefrina/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Ferro/química , Ferro/metabolismo , Ligantes , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Metais/química , Modelos Químicos , Peptídeos/química , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria/métodos , Espectrofotometria Ultravioleta/métodos , Fatores de Tempo
2.
Environ Microbiol ; 7(1): 88-97, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15643939

RESUMO

Bacteria may be beneficial for alleviating actinide contaminant migration through processes such as bioaccumulation or metal reduction. However, sites with radioactive contamination often contain multiple additional contaminants, including metals and organic chelators. Bacteria-based bioremediation requires that the microorganism functions in the presence of the target contaminant, as well as other contaminants. Here, we evaluate the toxicity of actinides, metals and chelators to two different bacteria proposed for use in radionuclide bioremediation, Deinococcus radiodurans and Pseudomonas putida, and the toxicity of Pu(VI) to Shewanella putrefaciens. Growth of D. radiodurans was inhibited at metal concentrations ranging from 1.8 microM Cd(II) to 32 mM Fe(III). Growth of P. putida was inhibited at metal concentrations ranging from 50 microM Ni(II) to 240 mM Fe(III). Actinides inhibited growth at mM concentrations: chelated Pu(IV), U(VI) and Np(V) inhibit D. radiodurans growth at 5.2, 2.5 and 2.1 mM respectively. Chelated U(VI) inhibits P. putida growth at 1.7 mM, while 3.6 mM chelated Pu(IV) inhibits growth only slightly. Pu(VI) inhibits S. putrefaciens growth at 6 mM. These results indicate that actinide toxicity is primarily chemical (not radiological), and that radiation resistance does not ensure radionuclide tolerance. This study also shows that Pu is less toxic than U and that actinides are less toxic than other types of metals, which suggests that actinide toxicity will not impede bioremediation using naturally occurring bacteria.


Assuntos
Elementos da Série Actinoide/toxicidade , Quelantes/toxicidade , Deinococcus/efeitos dos fármacos , Pseudomonas putida/efeitos dos fármacos , Radioisótopos/toxicidade , Shewanella putrefaciens/efeitos dos fármacos , Elementos da Série Actinoide/metabolismo , Elementos da Série Actinoide/farmacologia , Biodegradação Ambiental , Quelantes/metabolismo , Quelantes/farmacologia , Deinococcus/crescimento & desenvolvimento , Deinococcus/metabolismo , Testes de Sensibilidade Microbiana/métodos , Plutônio/metabolismo , Plutônio/farmacologia , Plutônio/toxicidade , Pseudomonas putida/crescimento & desenvolvimento , Pseudomonas putida/metabolismo , Poluentes Radioativos/metabolismo , Radioisótopos/metabolismo , Radioisótopos/farmacologia , Shewanella putrefaciens/crescimento & desenvolvimento , Shewanella putrefaciens/metabolismo
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