Figure 4
LCO-based morphotyping of Salmonella biofilms from agar plates. (a) Morphotypes of strain 3934 wt, ΔcsgD, ΔbcsA and ΔcsgA based on the drop assay on Congo red plates. (b) Normalised spectra of h-FTAA mixed with re-suspended biofilm colonies harvested from indicated strains grown for 48 h on LB agar w/o salt, with emission read at 545 nm. h-FTAA mixed with cellulose and PBS were assayed in parallel for reference. (c) Morphotype of a 3934 wt biofilm colony originating from an individual bacterium on Congo red plates monitored for three consecutive days. (d and e) Spectra of h-FTAA mixed with harvested 3934 wt biofilm colonies at (d) days 2 and 3, and (e) day 1, including cellulose and PBS for reference. Arrows indicate the shift in λmax for h-FTAA in the presence of various amounts of cellulose. n: 1 of 5 in b and d, n: 2 of 5 in e. Scale bars=1 cm. (f) Emission spectra of h-FTAA-supplemented cultures of strain 3934 wt, ΔbcsA, ΔcsgA and ΔcsgD after 24 h incubation, using excitation at 405 nm for curli detection. (g) Same experimental setup as in f using excitation at 500 nm for cellulose detection. Arrows indicate λmax of emission in ΔcsgA and ΔcsgD mutant strains. (h) Normalised fluorescence spectra for cellulose detection from g. Data represent n: 1 of 3. RFU, relative fluorescence units.
