1968 Volume 14 Issue 2 Pages 163-170
The effect of nystatin on the acid protease formation by Aspergillus niger as induced by sulfur deficiency was studied.
Nystatin at the concentration of 10μg/ml was found to inhibit the growth and the induced protease formation. The leakage of free amino acids from mycelia was also noted at this concentration. When nystatin was added to S-deficient cultures at different intervals in the induction period, a complete inhibition of protease formation was observed when added within the first 2.5hr. Later additions caused less effective inhibition.
After the protease induction in sulfur-deficient media, mycelia were either treated or not treated with nystatin and they were further cultured for protease formation on S-deficient media containing 14C-amino acid mixture. It was found that the nystatin-treated mycelium produced protease of higher specific radioactivity than the non-treated mycelium. This suggests that a fungal mycelium which has already established the protease-forming system can produce protease at the expense of exogenous nutrients, irrespective of the loss of the pool amino acid from the mycelium.