[Superoxide dismutase activity of Bacillus brevis var. G.-B. cells, producer of gramicidin C, in relation to cultivation conditions].
The activity of superoxide dismutase (SOD) in the cells of the microorganisms producing gramicidin S, B. brevis var. G.-B., ranged from 7 to 22 units per mg protein. When the culture was grown in a fermenter, the decrease in the concentration of dissolved oxygen in the medium to the minimum values corresponded to the decrease in the enzyme activity. By the end of the fermentation process, when consumption of oxygen by the culture lowered and its level in the medium increased, the enzyme activity increased. When the culture was grown in flasks, no effect of the medium aeration level on the enzyme activity was noted. This might be associated with rather high levels of dissolved oxygen in the medium in the flasks under all aeration conditions. Addition of manganese ions to the cultivation medium activated SOD in the cells of B. brevis. Synthesis of gramicidin S by the bacterial culture had no effect on the activity of SOD in the cells.