Antibiotic production by Streptomyces hygroscopicus CH-7 in medium containing Schiff base complexes

Influence of a modified media on Hexaene H-85 and Azalomycine B production by Streptomyces hygroscopicus CH-7 was investigated. The amino acid L-tryptophan, as a nitrogen source, was replaced with isatin-3-thiosemicarbazone and its complexes with some divalent metal ions. Isatin-3-thiosemicarbazone was synthesized in crude glycerol obtained as a byproduct in biodiesel production from sunflower oil. The complexes were charac­terized by elemental microanalysis and magnetic susceptibility, as well as, by Atomic absorption(AA), Fourier-transform infrared (FTIR) and Ultraviolet–visible (UV/VIS) spectro­scopic methods. The spectral studies indicated an octahedral geometry for the Mn(II), Fe(II) and Ni(II) complexes and a tetrahedral one for the Zn(II) complex. Comparing to the basal medium, isatin-3-thiosemicarbazone (ITC) and its metal complexes in the concentration of 0.5 g dm -3 showed better results in the antibiotics production. Use of medium supple­mented with the Fe(II) complex resulted in the maximum Hexaene H-85 and Azalomycine B concentrations of 306 µg cm -3 and 127 µg cm -3 ,respectively. Addition of ITC and its complexes changed the morphology of S. hygroscopicus CH-7 from filaments to pellets as a dominant shape in media resulting in higher antibiotic production.