FIG 3.

Divalent cation effects on calcimycin and cezomycin production by, and concentration ratio in, S. chartreusis NRRL 3882 as well as on CalG hydrolytic activity. (A) S. chartreusis NRRL 3882 treatment with 0.5 mM and 1 mM FeCl₂. (B) Ratios of calcimycin to cezomycin after treatment with different divalent cations (1 to 10 mM CaCl₂, MgCl₂, and MnCl₂ or 0.5 to 1 mM FeCl₂ and ZnCl₂). (C) Initial rates (measured from 0 to 15 min) of CalG hydrolysis in the presence of CaCl₂, MgCl₂, and MnCl₂ at 10 mM and in the presence of FeCl₂ and ZnCl₂ at 1 mM.