The relationship between growth phase and cyanogenesis inPseudomonas aeruginosa

Abstract

In batch cultures ofPseudomonas aeruginosa, hydrogen cyanide is produced primarily during the transition between logarithmic and stationary phases. This transient response is due to the synthesis of the enzyme system of cyanogenesis during mid to late logorithmic and the inactivation of this system in early stationary phase. Although glycine, the metabolic precursor of cyanide, stimulates cyanogenesis, it is not necessary to incorporate this amino acid in the growth medium to produce elevated enzyme levels. Under conditions of iron limitation (1×10⁻⁶ M), phosphate limitation (0.1 mM), and excess phosphate (250 mM), the culture produces low levels of the cyanogenic enzyme system. Increasing the carbon and energy source,l-glutamate, prolongs cyanogenesis and postpones the inactivation of the cyanogenic enzyme system.