Resistance to oxygen transfer in fermentation broths

The distribution of dissolved oxygen in agitated, sparger‐aerated aqueous solutions has been investigated by polarographic techniques. The results of the investigations are discussed in relation to earlier studies in bubble distribution in such systems. Liquid‐phase mixing is good at agitation intensities well below that necessary to disperse bubbles throughout the liquid. Suspended solids interfere with the transfer of oxygen unless they are freely suspended. Discrete fibers (paper‐pulp) are much easier to suspend than molds in either filamentous or pellet forms. Mass‐transfer at the cell‐liquid interface appears to be unaffected, in both bacterial and mold suspensions, by the intensity of agitation, provided that the organisms are freely suspended.