HYPHAL VACUOLATION AND FRAGMENTATION IN PENICILLIUM-CHRYSOGENUM

A link between vacuolation and fragmentation of Penicillium chrysogenum mycelia in stirred tank submerged fermentations is reported. Quantitative information on vacuolation and morphology was obtained by image analysis. In fed-batch fermentations the coincidence of the events of rapid vacuolation and the fall of the mean total and main hyphal lengths suggests that hyphal fragmentation is not necessarily due to ''shear'' alone. The physiological state of the hyphae, characterized by the proportions of vacuoles, was found to have a significant influence on the breakage of mycelial hyphae. It was found that the fragmentation was greater when the hyphae became heavily vacuolated following nutrient limitation in the culture, i.e., during the switch from the rapid growth to the production phase. (C) 1994 John Wiley and Sons, Inc.