Abstract

Cobalt is an important oligoelement required for bacteria; if present in high concentration, exhibits toxic effects that, depending on the microor-ganism under investigation, may even result in growth inhibition. The photosynthetic bacterium Rhodobacter (R.) sphaeroides tolerates high cobalt concentration and bioaccumulates Co+2 ion, mostly on the cellular surface. Very little is known on the chemical fate of the bioaccumulated cobalt, thus an X-ray absorption spectroscopy investigation was conducted on R. sphaeroides cells to gain structural insights into the Co+2 binding to cellular components. X-ray absorption near-edge spectroscopy and extended X-ray absorption fine structure measurements were performed on R. sphaeroides samples containing whole cells and cell-free fractions obtained from cultures exposed to 5 mM Co+2. An octahedral coordination geometry was found for the cobalt ion, with six oxygen-ligand atoms in the first shell. In the soluble portion of the cell, cobalt was found bound to carboxylate groups, while a mixed pattern containing equivalent amount of two sulfur and two carbon atoms was found in the cell envelope fraction, suggesting the presence of carboxylate and sulfonate metal-binding functional groups, the latter arising from sulfolipids ofthe cell envelope.

Autore Pugliese

• Carrozzini Benedetta , Caliandro Rocco , Trotta Massimo

Tutti gli autori

• Belviso B.D.; Italiano F.; Caliandro R.; Carrozzini B.; Costanza; A.; Trotta M.

Titolo volume/Rivista

BioMetals

Anno di pubblicazione

2013

ISSN

1572-8773

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

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Numero di citazioni Scopus

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Ultimo Aggiornamento Citazioni

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Settori ERC

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Codici ASJC

Non Disponibile