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, μ 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.