Germination and growth of neurospora at low water activities.

When the water activity (a(w)) of the medium is lowered by the addition of NaCl or nonelectrolytes, an inhibition of germination, growth rate, and total growth is observed in Neurospora crassa. Inhibition of conidial germination is separable from the other effects and is caused, in large measure, by the loss from conidia in media of low water activity of a substance that is essential for their germination. The substance is detectable in the medium and is also extractable from cultures. It is dialysable and thermostable, and it appears to be highly active. It is not detectable in complete medium.