The effects of cyanide on the growth and respiration of Enterobacter aerogenes in continuous culture.

The effect of cyanide on the physiology of lactate- and oxygen-limited Enterobacter aerogenes NCTC 10336 was studied in chemostat culture (D = 0.1 h-1). In the absence of cyanide, the molar growth yield from oxygen (YO2) under oxygen limitation was 60% of the carbon-limited value. A similar decrease in yield was observed in a lactate-limited culture (excess oxygen) which was continuously fed low concentrations of potassium cyanide. The cultures with the lower growth yields possessed respiratory systems less sensitive to inhibition by cyanide. This was particularly marked in cultures grown in the presence of cyanide. Increased cyanide resistance was associated with an increase in the concentration of a cytochrome oxidase tentatively identified as a d-type and the appearance of additional cytochromes tentatively identified as b-type.