Regulation of steroid 16alpha-hydroxylation in Streptomyces olivoviridis.

The steroid 16alpha-hydroxylase of Streptomyces olivoviridis was shown to be constitutive, but synthetized only in small amounts in the absence of cortisol. The induction of the enzyme with the steroidal substrate resulted in a distinct increase in the 16alpha-hydroxylation rate. This increase in activity, however, could be demonstrated only in later phases of culturing, after the growth of the mycelium was completed. The possible mechanisms controlling the activity of the enzyme during the growth phase of the culture are discussed.