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  • Steady state protein levels in Geobacter metallireducens grown with iron (III) citrate or nitrate as terminal electron acceptor.

Steady state protein levels in Geobacter metallireducens grown with iron (III) citrate or nitrate as terminal electron acceptor.

Proteomics (2007-11-13)
Angela J Ahrendt, Sandra L Tollaksen, Carl Lindberg, Wenhong Zhu, John R Yates, Kelly P Nevin, György Babnigg, Derek R Lovley, Carol S Giometti
ABSTRACT

Geobacter species predominate in aquatic sediments and submerged soils where organic carbon sources are oxidized with the reduction of Fe(III). The natural occurrence of Geobacter in some waste sites suggests this microorganism could be useful for bioremediation if growth and metabolic activity can be regulated. 2-DE was used to monitor the steady state protein levels of Geobacter metallireducens grown with either Fe(III) citrate or nitrate to elucidate metabolic differences in response to different terminal electron acceptors present in natural environments populated by Geobacter. Forty-six protein spots varied significantly in abundance (p<0.05) between the two growth conditions; proteins were identified by tryptic peptide mass and peptide sequence determined by MS/MS. Enzymes involved in pyruvate metabolism and the tricarboxylic acid (TCA) cycle were more abundant in cells grown with Fe(III) citrate, while proteins associated with nitrate metabolism and sensing cellular redox status along with several proteins of unknown function were more abundant in cells grown with nitrate. These results indicate a higher level of flux through the TCA cycle in the presence of Fe(III) compared to nitrate. The oxidative stress response observed in previous studies of Geobacter sulfurreducens grown with Fe(III) citrate was not seen in G. metallireducens.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Iron(III) nitrate nonahydrate, ≥99.95% trace metals basis
Sigma-Aldrich
Iron(III) nitrate nonahydrate, ≥99.999% trace metals basis
Sigma-Aldrich
Iron(III) nitrate nonahydrate, BioReagent, suitable for cell culture
Supelco
Iron standard for AAS, analytical standard, 10.00 g/L Fe in nitric acid, traceable to BAM
Sigma-Aldrich
Iron(III) nitrate nonahydrate, ACS reagent, ≥98%