Effect of single additive bivalent metal ions on the growth of Streptomyces clavuligerus and clavulanic acid production

Metal ions are the main impurities of water and media ingredients used in fermentation processes. In this research, the effect of Ca+2, Co+2, Cu+2, Fe+2, Mg+2, Mn+2 and Zn+2 as chloride and sulfate salts was studied on the clavulanic acid production and Streptomyces clavuligerus growth. All chloride salts had negative effect on clavulanic acid production and no clavulanic acid was produced in the media containing more than 1.5 mM ZnCl2 and 18 mM FeCl2. CuCl2 and CaCl2 increased biomass production, while the other chloride salts decreased it. Concentration of clavulanic acid in the 0.2 mM MnSO4 containing medium was 1.21 times more than that of control. There was no significant difference in antibiotic concentration in the medium containing 0.41 mM MgSO4 and control. Other sulfate salts decreased antibiotic production. MgSO4, CuSO4 and FeSO4 increased the biomass, while other sulfate salts decreased it. Minimum and maximum specific consumption rate of glycerol were seen in the medium containing CuSO4, and MnSO4, respectively.