Aromatic Amino Acids Required for Pili Conductivity and Long-Range Extracellular Electron Transport in Geobacter sulfurreducens

Probing single- to multi-cell level charge transport in Geobacter sulfurreducens DL-1

“…This result is also in direct contrast with our previous measurement with S. oneidensis MR-1 cells, which gave almost identical current output between window and nanohole electrodes 30 . At longer times, it is interesting to note that the nanohole electrode was also able to yield a current, albeit at a much smaller magnitude, which could be attributed to the ability of G. sulfurreducens to grow electrically conductive pili or excrete proteins to overcome the nanohole barrier [23][24][25] .…”

“…21), Geobacter sulfurreducens has only been associated with direct electron transfer mechanisms either through extracellular pilin decorated with cytochromes or the cell body itself 22,23 . Several groups 16,18 have actively been debating the mechanism of electron transfer by Geobacter after the publication of data suggesting that protein-based pilin had metal-like conductivity 24 and this metal-like conduction was due to secondary p-stacking of amino acids comprising the pilin itself 25 . Most conductivity and gene expression experiments with Geobacter sp.…”

Electrically Conductive Pili from Pilin Genes of Phylogenetically Diverse Microorganisms

“…To date, e-pili have been most intensively studied in Geobacter sulfurreducens and the closely related Geobacter metallireducens (Adhikari et al 2016, Feliciano et al 2015, Lampa-Pastirk et al 2016, Reguera et al 2005, Tan et al 2016b, Tan et al 2017, Vargas et al 2013, Xiao et al 2016. These studies have demonstrated that the e-pili of both G. sulfurreducens and G. metallireducens are sufficiently conductive along their length, under physiologically relevant conditions, to account for maximum potential rates of extracellular electron transfer (Adhikari et al 2016, Lampa-Pastirk et al 2016, Tan et al 2016b, Tan et al 2017.…”

“…These studies have demonstrated that the e-pili of both G. sulfurreducens and G. metallireducens are sufficiently conductive along their length, under physiologically relevant conditions, to account for maximum potential rates of extracellular electron transfer (Adhikari et al 2016, Lampa-Pastirk et al 2016, Tan et al 2016b, Tan et al 2017. Geobacter strains that lack e-pili, or express pili with diminished conductivities, are incapable of direct interspecies electron transfer (DIET) and Fe(III) oxide reduction (Liu et al 2014, Reguera et al 2005, Rotaru et al 2014a, Rotaru et al 2014b, Shrestha et al 2013, Summers et al 2010, Tan et al 2016b, Tremblay et al 2012, Vargas et al 2013. e-Pili are also required for Geobacter species to generate high current densities when electrodes serve as the sole electron acceptor (Liu et al 2014, Reguera et al 2006, Tan et al 2016b, Vargas et al 2013.…”

“…Geobacter strains that lack e-pili, or express pili with diminished conductivities, are incapable of direct interspecies electron transfer (DIET) and Fe(III) oxide reduction (Liu et al 2014, Reguera et al 2005, Rotaru et al 2014a, Rotaru et al 2014b, Shrestha et al 2013, Summers et al 2010, Tan et al 2016b, Tremblay et al 2012, Vargas et al 2013. e-Pili are also required for Geobacter species to generate high current densities when electrodes serve as the sole electron acceptor (Liu et al 2014, Reguera et al 2006, Tan et al 2016b, Vargas et al 2013. Increasing e-pili expression increases the conductivity of electrode biofilms and their current output , Yi et al 2009.…”