Proteolytic inactivation of an extracellular (1-->3)-beta-glucanase from the fungus Acremonium persicinum is associated with growth at neutral or alkaline medium pH.

The filamentous fungus Acremonium persicinum released high levels of proteolytic enzyme activity into the culture fluid during growth at pH 7 or above. Almost total inhibition of this crude activity by phenylmethylsulfonyl fluoride suggested that it was mainly due to the presence of a serine protease. This protease inactivated one of three extracellular (1-->3)-beta-glucanases produced by this fungus, although the activities of the remaining two (1-->3)-beta-glucanases did not appear to be affected. Growth of A. persicinum in acidic conditions resulted in the presence of much lower extracellular proteolytic activity and no apparent (1-->3)-beta-glucanase inactivation.