Figure 2.

Attachment of bacteria to banknotes following multiple extractions. □ washi-style paper notes (Japanese yen); ■ cotton notes (Chinese yuan); ○ cotton-linen notes (USA dollar); and ● polymer (Australian dollar). The bacterial inoculum (hand microbiome) in this experiment was facilitated by soaking the notes in nutrient broth in which volunteers washed their hands. Data shows remaining bacteria after a series of washings in saline buffer, relative to the first washing. Data are shown are the averages of quintuplicate (n = 5) samples while the error bars indicate standard deviation.