Fig. 3. Physical, electrical, and functional, analysis of the putative Syntrophus aciditrophicus PilA via heterologous expression in Geobacter sulfurreducens.

a Transmission electron micrograph of pili expression in the strain of G. sulfurreducens in which the native pilA was replaced with the S. aciditrophicus pilA. Examples of the location of pili are designated with white arrows. b Current–voltage profile for three separate locations on three pili expressed by S. aciditrophicus pili (data aggregated from individual plots in Fig.1d and Supplementary Fig. 2) and for three separate locations on three pili expressed in the SP strain of G. sulfurreducens in which the wild-type pilA was replaced with the S. aciditrophicus pilA (individual plots shown in Supplementary Fig. 3). c Current production by G. sulfurreducens with wild-type PilA; the synthetic Aro-5 PilA designed to yield poorly conductive pili; or S. aciditrophicus PilA. d Four-probe conductance (mean + standard deviation n = 9) of films of purified pili from strains of G. sulfurreducens expressing; S. aciditrophicus PilA compared with previously reported [33] conductances of pili derived from wild-type and Aro-5 strains of G. sulfurreducens.