Fig. 1

Impact of riboflavin and speC expression on current and biofilm formation on anode surfaces. Overexpression of speC resembles the phenotype after riboflavin addition, while deletion mutants seem to be blind for the riboflavin signal. The bar chart shows an increase in current density of 1.8-fold due to the addition of 37 nM riboflavin. Furthermore, the number of cells on the anode increases 2.4-fold. A very similar effect can be observed by the overexpression of speC. The addition of 37 nM riboflavin to a speC overexpressing strain leads to no increase in current density or in cell number. The deletion of speC leads to a slight decrease in current density, but the supply of 37 nM riboflavin does not show any significant effect on the speC knockout strain. Error bars represent the standard deviation from individual replicates (n = 3)