Production of copper coproporphyrin III by Bacillus cereus. II. Regulation of the biosynthesis of coproporphyrin III and its copper complex by oxygen and heavy metal ions.

The effects of oxygen and heavy metal ions on the production of copper coproporphyrin III were studied in Bacillus cereus strain 2. The formation of copper coproporphyrin III was found to be maximum when the cells were cultivated in G-medium at a low level of oxygen supply, but it was suppressed at extremely low oxygen supply levels. When the cells were cultured in metal-free G-medium, neither metal-coproporphyrin III nor coproporphyrin III was formed. In the presence of copper in the medium (400-100 micrometers), the formation of coproporphyrin III copper salt was maximum, but the addition of various heavy metal ions other than copper to the copper-free medium resulted in the formation of neither coproporphyrin III nor its metal chelates. Copper ions appear to be specifically required for coproporphyrin III formation.