EFFECT OF OXYGEN ON THE DEVELOPMENT OF RESPIRATORY ACTIVITY IN ESCHERICHIA COLI

Abstract

1) The respiratory activity of aerobically and anaerobically grown cells of Escherichia coli did not show marked difference when the substrate was glucose. The activity of anaerobically grown cells was distinctly lower than that of aerobically grown cells when respiration was measured on formate, acetate, malate, or succinate.
2) When anaerobically grown cells were aerated for 2.5hr in the absence of cell multiplication, the original low respiratory activity increased to a level of aerobically grown cells.
3) The development of respiratory activity in resting cells occurred only when several amino acids were present in the incubation mixture. The development was inhibited by ethionine, p-fluorophenylalanine, chloramphenicol, and glucose. The development was also inhibited by respiratory poisons such as cyanide, azide, carbon monoxide, and nitrophenols at concentrations that inhibited respiration of aerobically grown cells.
4) In aerobically grown cells a considerable amount of cytochromes a₂ and b₁, and a slight amount of cytochrome a₁ were present, while in anaerobically grown cells these cytochromes were present in a remarkably diminished amount. The cytochrome content of anaerobically grown cells did not increase significantly when resting cells were aerated for 2.5hr in a buffer containing only amino acids, but did increase when aerated for 4hr in a mixture containing amino acids and beef extract.