Figure 1.

A TSB agar-based ferrozine overlay assay for screening electrogenic bacteria. (a) A representative image of the ferric iron (Fe³⁺) reduction by bacteria in human fecal samples. The colonies which turn their colors from light to dark purple were randomly marked as F1, F2, and F3. A colony with light was labeled as F4. To establish their species, all selected colonies were sequenced and listed. (b) Image of the ferric iron reduction by bacteria in skin swabs. The colonies with dark purples were marked as S1, S2, and S3. A colony with light purple was indicated as S4. 16S rRNA sequencing was conducted for the identification of bacterial species for each colony (Supplementary Table S1). (c) Images of ferric iron reduction of S. epidermidis strain ATCC 12228, S1, and 5-MF-pretreated ATCC 12228 on TSB agar-based ferrozine overlay assays. (scale bars = 5 mm).