INFLUENCE OF MORPHOLOGY ON PRODUCT FORMATION IN ASPERGILLUS-AWAMORI DURING SUBMERGED FERMENTATIONS

The relationship between fungal morphology and heterologous protein pr oduction was examined for an Aspergillus awamori strain during a serie s of fermentations with a batch phase followed by a fed-batch phase. A gitation rate and inoculation concentration were used as controlled va riables to generate different fungal morphologies in 20-dm(3) stirred tank reactors. Morphology was quantitatively characterized using Image Analysis. The different agitation rates and inoculum concentrations h ad large effects on the development in hyphal length and number of tip s during the fermentations. A reduced inoculum concentration resulted in a more branched mycelium. The different agitation rates affected th e morphology after 30 h of fermentation significantly but did not affe ct the start time of fragmentation. A 3-fold increase in hyphal length increased the apparent viscosity by a factor of 7. The observed morph ological differences had only a limited effect on product formation, s uggesting that the structural features such as hyphal length and numbe r of tips are of less importance for product formation. The primary ef fect of morphology on product formation is due to viscosity.