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Abstract
Sporulation of Aspergillus niger was induced in continuous tower fermenters by restricting growth with nitrate limitation. Semi-continuous production of spores was achieved in a single-stage fermentation by alternating full-nutrient and nitrogen-deficient media to the culture. Continuous spore production was obtained in a two-stage fermentation system using the first stage for the growth of vegetative mycelium under optimum conditions and the second, larger, stage for sporulation induction in a constant nitrogen-deficient environment. Spores were produced from much simplified sporulation structures. Using a new sporulation index (Ω), which relates spore numbers produced to the quantity of substrate utilized, the average production efficiency of the two-stage continuous system was shown to be more than twice that of the semi-continuous production system. The tower fermenter was shown to be ideal for controlling organism morphology, thus providing conditions which allowed the development of continuous fungal sporulation.
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