Figure 1.
Morphological transformations of K. radiotolerans observed at mid-exponential (A.), late exponential (B.), and early stationary (C.) growth phases.
Cells were collected from liquid culture (TGY), stained with acridine orange and viewed by confocal laser scanning microscopy.
Figure 2.
Physiological response of K. radiotolerans to copper. Panel A: Growth response to increasing copper concentration. Panel B: Cytoplasmic accumulation of copper during growth. The experimental treatments are as follows; • TGY (No metal control), ○ 0.1 mM Cu(II), ▾ 0.75 mM Cu(II), Δ 1.0 mM Cu(II), ▪ 1.5 mM Cu(II).
Figure 3.
Fluorescent micrographs of reactive oxygen species (ROS, in green) in K. radiotolerans cultures (mid-exponential phase) as a function of copper concentration in the growth medium.
A 10 µm scale bar is shown for each micrograph and lettered panel designations correspond to the following treatments: A.) No copper control, B.) 0.1 mM Cu(II) C.) 0.75 mM Cu(II), D.) 1.0 mM Cu(II), and E.) 1.5 mM Cu(II).
Figure 4.
Composite heat map showing the proteomic response categories of K. radiotolerans to copper.
Relative change in peptide abundance is shown for each of the copper growth conditions (0.1, 0.75, 1.5 mM Cu(II); the median response was calculated for biological triplicates) at a distinct growth stage (16 hr onset of exponential, 22 hr mid-exponential, 32 hr stationary phase) relative to the no copper controls.
Figure 5.
Superoxide dismutase activity profiles during the growth of K. radiotolerans in copper supplemented medium.
Cultures (n = 3) were grown in TGY medium amended with CuSO4 and incubated at 28°C and 150 rpm. Growth phases were operationally defined as follows; onset of exponential growth at 16 hr, mid-exponential phase at 22 hr, transition from exponential – stationary phase at 26 hr, and stationary phase at 32 hr. The experimental treatments are as follows; • TGY (No metal control), Δ 0.1 mM Cu(II), ○ 0.75 mM Cu(II), ▪ 1.5 mM Cu(II).
Figure 6.
Glutathione levels during the growth of K. radiotolerans in copper supplemented medium.
Cultures (n = 3) were grown in TGY medium amended with CuSO4 and incubated at 28°C and 150 rpm. Growth phases were operationally defined as follows; onset of exponential growth at 16 hr, mid-exponential phase at 22 hr, transition from exponential – stationary phase at 26 hr, and stationary phase at 32 hr. The experimental treatments are as follows; • TGY (No metal control), Δ 0.1 mM Cu(II), ○ 0.75 mM Cu(II), ▪ 1.5 mM Cu(II).