Pellet Formation and Fragmentation in Submerged Cultures of Penicillium chrysogenum and Its Relation to Penicillin Production

Abstract

The spores of Penicillium chrysogenum are of the noncoagulating type, and after spore germination a culture of disperse mycelia is obtained. In this study, it is shown that when the hyphal elements increase in size, they may agglomerate, and depending on the operating conditions, these agglomerates may develop into pellets with a dense core. The influence of initial spore concentration and agitation rate on agglomeration, leading to pellet formation, was studied. For a low concentration of spores in the inoculum, only a few hyphal elements agglomerate and pellets with a small diameter are obtained. At higher spore concentrations, many hyphal elements agglomerate and develop into large diameter pellets. Finally, at a very high spore concentration in the inoculum, the final hyphal element size is small and agglomerates therefore are not formed. With a high agitation rate, the agglomeration of hyphal elements is reduced. In a repeated fed-batch cultivation, where there was a shift from pellet morphology to disperse mycelia, it was found that there is no relation between macroscopic morphology and penicillin production by P. chrysogenum. The morphology was quantified throughout the repeated fed-batch cultivation, and both the pellet diameter and the concentration of pellets were affected by the agitation rate.

Effect of Environmental Factors in the Decolorization of Remazol Brilliant Blue R by Polyporus Sp. S133

“…Good mixing, mass and heat transfer require a threshold level of agitation. On the other hand, a high agitation rate leads to a high energy dissipation rate connected with high shear stress, which may result in fragmentation and damage of cells and the mycelial network [22][23][24][25] . The optimal growth pH for Polyporus sp.…”

Unlocking Streptomyces spp. for Use as Sustainable Industrial Production Platforms by Morphological Engineering

“…The mycelial lifestyle of actinomycetes results in production processes that are typically characterized by a complex rheology (1,7,10). This results in mass-related mechanical stress, in heat transfer problems, and in oxidative stress (16,17). The consequential problems related to filamentous growth include (i) slow growth rates and highly viscous cultures, (ii) large mycelial clumps that are mainly physiologically active around the edge of the clump (pellet), with significant oxygen and nutrient transfer problems towards the center, (iii) mixing requirements that necessitate high stirrer speeds, resulting in uncontrolled fragmentation and lysis of the mycelium, and (iv) complex and therefore expensive downstream processing.…”

Intracellular pH determination of pristinamycin-producing Streptomyces pristinaespiralis by image analysis

“…They can be present as a consequence of the alteration of fluffy pellets caused by shearing forces produced by the increased agitation necessary for the regulation of dissolved oxygen. Moreover, simultaneous analysis of all morphologies present in the culture has been reported to be impossible since a i100 oil immersion objective (i1000 final magnification) generally requires the use of coverslips for filament analysis which can disturb the physiology of the cells in the pellets (Nielsen et al, 1995 ;Cox et al, 1998).…”