Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism▿
AUTOR(ES)
Poulain, Alexandre J.
FONTE
American Society for Microbiology (ASM)
RESUMO
Diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [Fe(II)] under anaerobic conditions, both phototrophically and chemotrophically. Yet whether they can do this under conditions that are relevant to natural systems is understood less well. In this study, we tested how light, Fe(II) speciation, pH, and salinity affected the rate of Fe(II) oxidation by Rhodobacter capsulatus SB1003. Although R. capsulatus cannot grow photoautotrophically on Fe(II), it oxidizes Fe(II) at rates comparable to those of bacteria that do grow photoautotrophically on Fe(II) as soon as it is exposed to light, provided it has a functional photosystem. Chelation of Fe(II) by diverse organic ligands promotes Fe(II) oxidation, and as the pH increases, so does the oxidation rate, except in the presence of nitrilotriacetate; nonchelated forms of Fe(II) are also more rapidly oxidized at higher pH. Salt concentrations typical of marine environments inhibit Fe(II) oxidation. When growing photoheterotrophically on humic substances, R. capsulatus is highly sensitive to low concentrations of Fe(II); it is inhibited in the presence of concentrations as low as 5 μM. The product of Fe(II) oxidation, ferric iron, does not hamper growth under these conditions. When other parameters, such as pH or the presence of chelators, are adjusted to promote Fe(II) oxidation, the growth inhibition effect of Fe(II) is alleviated. Together, these results suggest that Fe(II) is toxic to R. capsulatus growing under strictly anaerobic conditions and that Fe(II) oxidation alleviates this toxicity.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2772431Documentos Relacionados
- Immobilization of Radionuclides and Heavy Metals through Anaerobic Bio-Oxidation of Fe(II)
- Biogenic Magnetite Formation through Anaerobic Biooxidation of Fe(II)
- Light-dependent degradation of nitrophenols by the phototrophic bacterium Rhodobacter capsulatus E1F1.
- The phosphatidylserine receptor from Hydra is a nuclear protein with potential Fe(II) dependent oxygenase activity
- Mechanism of light-dependent proton translocation by bacteriorhodopsin.