Use of a temperature-sensitive, protoplast-forming Neurospora crassa strain for the detection of antifungal antibiotics.

Protoplasts of the temperature-sensitive osmotic-1 mutant of Neurospora crassa grew and divided as cell wall-less cells when incubated under certain conditions at 37 degrees C. Each protoplast regenerated cell wall and formed a mycelium when the temperature was shifted to 22 degrees C. Cell wall regeneration, but not cell growth, was prevented by the inhibition of cell wall assembly functions. Thus, the inhibition of cell wall regeneration could serve as an indicator of the mode of action of antibiotic drugs. A method for detecting cell wall-inhibiting antifungal compounds with osmotic-1 protoplasts is described.