Optimal production conditions of an extracellular protease from Streptomyces corchorusii ST36.

Forty different isolates of streptomycetes from Egyptian soil were screened for their proteolytic activity in eight different media, for different time intervals and under different culture conditions. One of them, an isolate of Streptomyces corchorusi ST36 was the most active and glucose-aspartic acid-ammonium nitrate medium (GAA) was the best medium. Maximum production of the extracellular proteolytic activity by S. corchorusii ST36 (383 U/ml) was obtained at 30 degrees C after 5 days in shaked cultures. The optimal medium for maximum production of protease contained the soluble starch 2% (w/v), aspartic acid at 0.25% (w/v) and ammonium nitrate at 0.1% (w/v), at initial pH 6.0.