Fig. 1.

pDawn control of the adhesin Ag43 enables light-controlled deposition of biofilm onto surfaces. (A) Ag43 was inserted downstream of pDawn control. Escherichia coli with pDawn-Ag43 can be optically stimulated with a projector to express Ag43 and to form biofilm at surfaces. (B) Cells engineered with the pDawn-Ag43 construct form biofilm contingent upon illumination (***P $<$ 0.001). Wild-type and pDawn controls fail to form significant biofilm, and pBAD-Ag43 expression forms biofilm regardless of illumination. Representative 96-well crystal violet stains are shown below. (C) Increasing illumination intensity increases biofilm formation, saturating past ∼41 $\mu$W/cm². Dashed curve, fit with Monod model. (D) Increasing illumination time increases biofilm formation up to approximately 8 h. Dashed curve, linear fit. (B–D, error bars represent SD, n = 4 wells.)