Effect of cultivation conditions on the activity of the beromycin producerStreptomyces glomeratus 3980 and its spontaneous variants

Optimal conditions for the submerged cultivation ofStreptomyces glomeratus 3980, producer of the anthracycline antibiotics beromycins, and its variants were sought in media with glucose, soybean meal and salts differing in the content of ammonium sulphate. As compared with the original activity of the strain the antibiotic titre of some variants increased about 12 times on increasing the glucose concentration from 3 to 5 %, or on omitting CaCO₃ from the medium (i.e. under conditions leading to an increased production of propionic acid and suppression of production of the melanin-like pigment). In melanin-less variants accumulating propionate even under standard conditions the activity increased about 18–40 times in the medium with 3 % glucose and 0.2 % CaCO₃ under conditions of more intensive aeration (i.e. under conditions when no propionic acid accumulated). Individual strains also differed in the requirement for (NH₄)₂SO₄ in the medium, their response to changes of volume of the vegetative inoculum and sensitivity to MgSO₄.7H₂O. The biosyiithetic activity of all strains was inhibited by the addition of ZnSO₄.7H₂O or CaCl₂ and substitution of glucose with starch, lactose or sucrose.