FIG. 3.

Induction of the cyanide-insensitive NADH oxidase activity in P. pseudoalcaligenes CECT5344 (A) and the CIO1 mutant (B). Cells were precultured in 2 mM ammonium medium until nitrogen was exhausted. The cultures were separated in four flasks, and after treatment for 4 h with 2 mM of ammonium (NH₄Cl), nitrogen free medium (−N), 2 mM of potassium cyanide (KCN), or 2 mM of cyanide from jewelry residue (RCN), the membrane fractions were obtained as described in Materials and Methods. The NADH oxidase activities were determined after addition of 2 mM KCN alkalinized with KOH (black bars) or 4 mM KCl as controls (gray bars). Prot, protein.