Oxygen transfer in streptomyces fermentation broths

The oxygen transfer coefficient has been investigated in S. noursci and S. lavendulae fermentation broths obtained from fermentors of different operating volumes (61., 30001., 20,0001.). Fermentors had KLas values ranging from 1.0 to 17.0 min−1, calculated from sulphite oxidation rates. The dynamic measurement of the volumetric oxygen transfer coefficient. (KLa) has been performed in the different fermenting systems. As the fermentation progressed, especially in the first stages, KLa values have decreased in both fermentations and in each system of fermentors. In order to characterise the whole fermenting system an average KLas was calculated from the obtained KLa values. The average KLa grew with increasing KLas values and ranged from 0.03 to 3.72 min−l. Some factors possibly having an influence on the, change of KLa have been studied. The oxygen transfer coefficients of the broths have been measured in falling films and ranged from 0.05 to 0.4 cm min−1. The flow conditions have been characterized by Reynolds numbers of broths varying between 1.0 and 60.0. The average thickness of the falling films have been measured and plotted against Reynolds number. The Re+ which is the breaking‐point of the plot increased as the fermentation proceeded. In the region of Re+ the values of the oxygen transfer coefficient increased rapidly. An approximate correlation could be established between the Re+ and the physical properties of fermentation broth.