Biochemistry of bacterial dissimilatory metal reduction
Final Report Abstract
The aim of the research project was to unravel the mechanisms of periplasmic electron transfer in the model organism Shewanella oneidensis MR-1. The detailed understanding of the processes leading to extracellular electron transport is fundamental for the ambition of converting E. coli into an organism capable of extracellular respiration. During this funding period the reaction room of the periplasm was characterized with respect to cytochrome content and reaction behavior. Two highly abundant Cytochromes (STC and FccA) could be identified to have a crucial importance concerning extracellular electron transfer. The loss of both electron transferring cytochromes leads to growth deficiencies on three terminal electron acceptors – DMSO, nitrate and ferric citrate. It could also be shown that the activity of STC expressing E. coli cells reducing methylene blue was severely increased, indicating its role as primary CymA oxidase. Further studies identified an electron guiding role for either STC and FccA. In nitrate reducing conditions the general reduction pattern (meanwhile occurrence of a nitrite accumulation) and separation between nitrate reduction to nitrite and nitrite reduction to ammonia is abolished.
Publications
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Proof of principle for an engineered microbial biosensor based on Shewanella oneidensis outer membrane protein complexes. Biosens Bioelectron. 2013 Sep 15;47:285-91
Golitsch F, Bücking C, Gescher J
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A dynamic periplasmic electron transfer network enables respiratory flexibility beyond a thermodynamic regulatory regime. ISME J. 2015 Aug;9(8):1802-11
Sturm G, Richter K, Doetsch A, Heide H, Louro RO, Gescher J
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Unbalanced fermentation of glycerol in Escherichia coli via heterologous production of an electron transport chain and electrode interaction in microbial electrochemical cells. Bioresour Technol. 2015 Jun;186:89-96
Sturm-Richter K, Golitsch F, Sturm G, Kipf E, Dittrich A, Beblawy S, Kerzenmacher S, Gescher J
