Effects of Carbon dioxide on the Rheological behavior and oxygen transfer in submerged penicillin fermentations

Fermentations of Penicillium chrysogenum have been made with different CO(2) contents in the influent gas streams. The rheological behavior of the culture broth was found to be significantly changed by exposure to high levels of CO(2). This is attributed to the wide variation in the morphology of P. chrysogenum, from normal mycelia with long hyphae to roughly spherical pellets when subjected to high levels of CO(2). A correlation has been developed relating volumetric O(2) transfer coefficients, k(L)a, with the effective O(2) diffusion coefficients, D(e), and the apparent viscosities, mu(app), based on the results obtained in this study. The use of CO(2) as a potent means for altering the rheological properties of culture broths and consequently improving the O(2) transfer capabilities in penicillin fermentations was clearly demonstrated.