A new sensor,the “filtration probe,” for quantitative characterization of the penicillin fermentation. II. The monitor of mycelial growth

Biomass concentration during penicillin production can be estimated rapidly and with reasonable accuracy using the “filtration probe.” The basis for the measurement is the volume of the filter cake which, in contrast to the conventional “packed-cell volume” measured by centrifugation, is only moderately affected by the morphology of the mycelia. The influence of the mycelial morphology on the specific filter cake volume υ (cm³ cake/g dry cells)] can additionally, to a large extent, be predicted from the (specific) filtration resistance of the broth. During the rapid (exponential) growth period, the specific cake volume is, however, more variable and typically exhibits a transient maximum value. The presence of such a maximum can be explained by a simple model for exponential growth of single mycelial particles. this model is based upon conventional kinetics for hyphae elongation and branching and applies well to experimental data (filtration behavior as well as microscopic studies) provided hyphae fragmentation is negligible (i.e., at high growth rates, μ ? μ_max).