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. 2019 Mar 8;8:e43920. doi: 10.7554/eLife.43920

Figure 1. Mechanical instability drives V. cholerae biofilm morphogenesis.

(A) Bright-field images of biofilms grown for 2 days on the designated percentages of agar. (B) Schematic of the wrinkling and delamination processes that occur during biofilm expansion. Red with a black outline denotes the biofilm. Gray denotes the substrate, agar in this case. (C) Three-dimensional (3D) profile of two colliding biofilms, initially inoculated 9 mm apart, grown on a 0.6% agar plate for 36 hr. (D) Transmission image of a V. cholerae biofilm grown for 35 hr (top) and 48 hr (bottom) on a 1.0% agar plate. (E) Transmission image of a V. cholerae biofilm inoculated as a line and grown for 30 hr on a 0.5% agar plate. In panels (D) and (E), blue arrows denote the expansion directions, and black arrows denote the tangential directions along which compressive stress accumulates. All scale bars are 5 mm.

Figure 1.

Figure 1—figure supplement 1. Quantification of V. cholerae biofilm surface morphologies.

Figure 1—figure supplement 1.

(A) The characteristic wavelength of the radial morphological features, λ, decreases with increasing agar concentration. (B) Transmitted light intensity profiles measured close to the outer edges of biofilms, I, show that the amplitudes of the radial features become more regular with increasing agar concentration. Left: typical profiles of transmitted light intensity, I, along the rims of 2-day-old biofilms for the designated agar concentrations. Middle: a closeup view of the extracted intensity profile from the bottom trace. The prominence of each peak, ΔIp, is used as a proxy for the height/amplitude of the corresponding radial feature. Right: probability distribution of ΔIp for the designated agar concentrations.
Figure 1—figure supplement 1—source data 1. Quantitation of V. cholerae biofilm surface morphologies.
elife-43920-fig1-figsupp1-data1.xlsx (103.4KB, xlsx)
DOI: 10.7554/eLife.43920.005
Figure 1—figure supplement 2. Wrinkling and delamination transitions are rapid.

Figure 1—figure supplement 2.

A biofilm grown on a 0.5% agar substrate was imaged at the designated times. Top: bright-field images. Bottom: fluorescent signal from the SytoX Green stain marking dead cells. White arrows indicate emerging morphological features. The wrinkling and delamination instabilities occur within a 2-hr window. No localized cell death was observed to precede the formation of wrinkles or blisters. Scale bar: 5 mm.