Kinetics of the growth of mycelial pellets of Aspergillus nidulans

Abstract

1. The radius of Aspergillus nidulans pellets grown singly (i.e. l/flask) increased linearly with time for most or all of their growth; they grew at about half the rate of colonies of the mould upon solid medium. The final pellet diameter, the duration of the linear growth phase and the initial radial growth rate decreased as the pellet concentration was increased. 2. Single pellets initially increased in dry weight at an exponential rate; the specific growth rates at 20°, 25° and 30°C but not at 37°C were almost identical with the organism's maximum specific growth rates at these temperatures. 3. The cube root of the dry weight of pellets grown singly also increased linearly with time for most or all of their growth, but a smaller proportion of the total growth of cultures inoculated with several pellets was of this form. Cube root kinetics were only maintained as long as the pellets grew at a constant rate. 4. When Aspergillus nidulans cultures were inoculated with various conidial concentrations the ratio, conidia per flask: pellets formed per flask, varied between 2–6×104. Cultures only grew at the maximum specific growth rate when inoculated with at least 6×105 conidia/ml of medium.