FIG 6.

Accumulation of intracellular copper content in E. coli cells under anaerobic conditions. E. coli cells were grown in LB medium supplemented with or without 0.2 mM CuCl₂ for 4 h under anaerobic or aerobic conditions. The E. coli cells were then washed with buffer containing 20 mM Tris (pH 8.0) and 500 mM NaCl twice and treated with 2.5% (vol/vol) nitric acid. The samples were subjected to EPR measurements. Spectrum 1, E. coli cells grown in LB medium under aerobic conditions; spectrum 2, E. coli cells grown in LB medium supplemented with 0.2 mM CuCl₂ under aerobic conditions; spectrum 3, E. coli cells grown in LB medium under anaerobic conditions; spectrum 4, E. coli cells grown in LB medium supplemented with 0.2 mM CuCl₂ under anaerobic conditions.