Properties of an extracellular -galactosidase secreted by Neurospora crassa.

An extracellular beta-galactosidase with an activity optimum at about pH 4 was found to occur in the filtrates of Neurospora crassa strain 74A when this mold was grown on certain sugars. This activity accounted for a substantial portion of the beta-galactosidase activity in the culture. The beta-galactosidase in the medium appeared to be a secreted, extracellular enzyme, not a product of cell lysis. The extracellular activity was found to have physical and kinetic properties similar to those of an intracellular beta-galactosidase previously found in Neurospora. Some conditions for the production and concentration of the enzyme are described.