[Growth and development of a gramicidin S producer under limiting conditions with dissolved oxygen]

When the gramicidin S-producing organism is cultivated under submerged conditions its growth is limited by dissolved oxygen in the medium. The beginning of the decrease in the growth rate and respiration of the bacterial cells is observed at the dissolved oxygen concentration equal to approximately 20--40 per cent of the saturation level. The following decrease in the oxygen concentration up to the critical values results in termination of the culture growth. As a result a part of the cells die and the survivors begin intensively multiply. With decreasing of the aeration and agitation rates the step-wise character of the culture growth appears to be more pronounced. With an increase in the aeration and agitation rates the time of the culture growth under conditions of limited aeration decreases, while the synthesis of gramicidin S in this case often decreases. Limitation of the culture growth with dissolved oxygen is accompanied by a decrease in the value of the economic coefficient which is evident of a significant dissociation between the energy and constructive metabolism of the organism under such conditions.