Electrically conductive pili from pilin genes of phylogenetically diverse microorganisms.

TitleElectrically conductive pili from pilin genes of phylogenetically diverse microorganisms.
Publication TypeJournal Article
Year of Publication2018
AuthorsWalker DJf, Adhikari RY, Holmes DE, Ward JE, Woodard TL, Nevin KP, Lovley DR
JournalISME J
Date Published2018 Jan
KeywordsDeltaproteobacteria, Electric Conductivity, Fimbriae Proteins, Fimbriae, Bacterial, Methane, Oxidation-Reduction, Phylogeny

The possibility that bacteria other than Geobacter species might contain genes for electrically conductive pili (e-pili) was investigated by heterologously expressing pilin genes of interest in Geobacter sulfurreducens. Strains of G. sulfurreducens producing high current densities, which are only possible with e-pili, were obtained with pilin genes from Flexistipes sinusarabici, Calditerrivibrio nitroreducens and Desulfurivibrio alkaliphilus. The conductance of pili from these strains was comparable to native G. sulfurreducens e-pili. The e-pili derived from C. nitroreducens, and D. alkaliphilus pilin genes are the first examples of relatively long (>100 amino acids) pilin monomers assembling into e-pili. The pilin gene from Candidatus Desulfofervidus auxilii did not yield e-pili, suggesting that the hypothesis that this sulfate reducer wires itself with e-pili to methane-oxidizing archaea to enable anaerobic methane oxidation should be reevaluated. A high density of aromatic amino acids and a lack of substantial aromatic-free gaps along the length of long pilins may be important characteristics leading to e-pili. This study demonstrates a simple method to screen pilin genes from difficult-to-culture microorganisms for their potential to yield e-pili; reveals new sources for biologically based electronic materials; and suggests that a wide phylogenetic diversity of microorganisms may use e-pili for extracellular electron exchange.

Alternate JournalISME J
PubMed ID28872631
PubMed Central IDPMC5739001