Morphological measurements on Penicillium chrysogenum broths by rheology and filtration methods

The morphology parameters of mycelial culture (Penicillium chrysogenum) were measured and quantified by rheology and filtration methods. Two of the morphology parameters obtained from rheology measurements, delta defined by the Casson equation and delta* defined by intrinsic viscosity, were found to vary systematically with broth age and with the observed morphology by microscopy. Three of the filtration parameters, hyphal density, Kozeny constant, and index of compressibility, are demonstrated as sensitive indicators of the broth age and mycelial morphology. Two of the morphology parameters, delta and delta*, were used to cross-correlate with hyphal density. Because various mycelial fermentations require different growth morphologies (pellet and filament) for optimum product yield and the morphology of mycelial broths varies with broth age, it is suggested that these morphology parameters could be used to represent the morphology of mycelial broths quantitatively.