Secretion of Proteinases with Fibrinolytic Activity by Micromycetes of the Genus Aspergillus

Abstract

Proteolytic activity of extracellular enzymes of 11 strains of different Aspergillus species was studied. Comparison of the enzymatic indices of strains grown on agar medium containing either casein or fibrin allowed the selection of the strain Aspergillus terreus 2 as a promising producer of fibrinolytic proteases. It was found that A. terreus 2 proteinases demonstrated maximum activity at pH 8.0. The highest values of fibrinolytic and total proteolytic activities expressed in U_Tyr (amount of micromoles of tyrosine released from fibrin or casein for 1 min) were 34.0 and 358.3, respectively. Maximum activities were detected when growing the producer on a medium containing only amine nitrogen sources (fish flour hydrolysate and peptone); however, the amount of extracellular protein and the specific fibrinolytic and total proteolytic activities were greater in the medium containing both mineral and amine nitrogen sources (fish flour hydrolysate and sodium nitrate) than in the medium containing only fish flour hydrolysate and peptone as nitrogen sources.