Role of amino acids and micronutrients on biosynthesis of spiramycins

Abstract

The production of spiramycin using a synthetic basal medium, to which amino acids, vitamins and metallic ions were added, was investigated. L‐Tryptophan was found to be the amino acid which best increased the antibiotic yield. Addition of vitamins to the fermentation medium did not increase the antibiotic output, while the addition of different concentrations of trace elements such as Co(NO3)2 ZnCl2 (NH4)2Mo7O24 and MnCl2 improved the antibiotic yield. High concentrations of these trace elements decreased the antibiotic yield and directed the microbial activities towards biosynthesis of spiramycin II and III—these are less toxic than spiramycin I. Optimum concentrations of Co(NO3)2, ZnCl2, (NH4)2Mo24O7, MnCl2 which supported the antibiotic yield were 5 × 10−1, 5 × 10−3, 5 × 10−3 and 5 × 10−3 g dm−3, respectively.