Figure 1.
Optical phase-contrast microscopy image of a H. walsbyi square cell.
The numerous light dots represent gas vesicles. Overall size is 10×10 µm. Scale bar 1 µm.
Figure 2.
AFM images of a H. walsbyi folded cell.
Amplitude (a) and phase (b) images show a cell with its upper right-hand corner folded. Enlarged images of the white boxed areas show the spotted region (c) and the striped region (d); the dashed line is a guideline along the border of the folded corner. Scale bars: 1 µm (a, b), 400 nm (c), 100 nm (d).
Figure 3.
AFM analysis of striped regions.
a) Amplitude and phase images of striped regions observed on a dried cell. b) Average profile line extracted from the region indicated with the dotted line in the phase image and its Fourier analysis results in the bar graph. The same analysis was applied to the striped region indicated with the full line in Fig. 2d.
Figure 4.
AFM analysis of H. walsbyi S-layer.
a) Zoom view of Fig. 2c, showing the S-layer corrugation made up of units 16–20 nm apart represented by dashed circles. Scale bar is 20 nm. b) Fourier analysis. In the inset is the 2D PSD image within a frame of ±74.2 µm−1. Average radial profile of PSD versus spatial frequency (dotted line) and its enhancement after the subtraction of the 1/f background (full line).
Figure 5.
AFM images of H. walsbyi cell evolution during the drying process.
a) Height (H) and phase (P) images of cells at the beginning of the process (time t = 0). In height imaging, cells present an external capsule appearing as a thin film disrupted in some locations. One big laceration is indicated by the white arrow. In phase imaging, capsule lacerations correspond to white spots. In the following height images (b) acquired at different times during the drying process, the cells decrease in volume and lose their capsule, uncovering the underlying cell layer. Scale bar 2 µm.
Figure 6.
AFM images of H. walsbyi external capsule disruption during the drying process.
Height images are enlargements of two representative regions (white boxes in Fig. 5b time t = 4 h 30 min) showing capsule evolution during the drying process. The capsule features holes or lacerations that break up over time, gradually increasing in size. At the end of the process remnants of the capsule can still be seen, mainly located in the valleys between the protrusions (white arrows time t = 6 h). Scale bar 100 nm.