Studies on phosphatase activity of Streptomyces fradiae 3535 grown in three different media indicate that neomycin formation varies directly with enzyme activity, sodium nitrate–maltose–mineral salts medium giving the highest yields of alkaline phosphatase and neomycin. S. fradiae contains more than one alkaline phosphatase and the phosphatase responsible for hydrolysis of neomycin phosphate appears to be substrate specific. The same enzyme apparently hydrolyses both the N–P and P–O–P bonds of neomycin pyrophosphate. The enzyme is stimulated by Ca2+, is inactive at a pH below 7 and is inhibited by EDTA. Enzymic activity increases when mycelia are incubated in mineral salts medium, but decreases when phosphate or glucose is included in the medium, although the latter is more effective. The inhibitory effect of EDTA on neomycin formation by resting mycelia is completely reversed by Ca2+.
- © 1971 The Biochemical Society