Fig. 4.

Expression of nap-α in cells growing on agar plates under various conditions as measured by β-galactosidase activity. The ccoN and prrA strains are mutants of strain 2.4.3 in which these genes have been inactivated. Black bars represent expression under microoxic growth, white bars represent expression under microoxic growth with 10 mM nitrate, dark gray bars represent expression under oxic growth, and light gray bars represent expression under oxic growth with 10 mM nitrate. There are no microoxic values for the ccoN strain because this mutant cannot grow under low-oxygen conditions.