Gene clusters encoding putative outer membrane electron conduits have specific roles during metal and electrode respiration in Geobacter sulfurreducens

摘要: At least five gene clusters in the Geobacter sulfurreducens genome encode putative outer membrane 'electron conduits', which are redox active complexes containing a periplasmic multiheme c-cytochrome, integral β-barrel, and lipoprotein. Single gene-cluster deletion all possible combinations of mutants were constructed grown with graphite electrodes poised at +0.24 V -0.1 vs. SHE, Fe(III)- Mn(IV)-oxides, soluble Fe(III)-citrate. Different necessary for reduction each electron acceptor. For example, only ΔextABCD cluster mutant had severe growth defect on potentials, but this mutation did not affect Fe(III)-oxide, Mn(IV)-oxide, or Fe(III)-citrate reduction. During metal oxide reduction, previously described omcBC caused defects, additional components ΔomcBC background, such as extEFG, was to produce defects greater than 50% compared wild type. Deletion required abolish Mutants one able reduce particular terminal acceptors better type, suggesting routes improvement by targeting substrate-specific transfer pathways. Our results show G. utilizes different conduits depending extracellular acceptor used.