Breeding The Bacillus Subtilis Strain Overproducing Fibrinolysin And Optimizing Its Fermentation Conditions

20 Bacillus strains with fibrinolysin activity were isolated from many withered straw and natto samples. According to the identification of the morpha, the colonies and the physiological and biochemical characteristics, the screened strains were confirmed to be Bacillus subtilis. By solid and liquid fermentation to compare the fibrinolysin activity of these strains,FM2,as the higherctivity strain,was seleted and investigated its fermentation conditions. The result of fermentation kinetics showed that fibrinolysin was produced synchronously with cell growth in solid fermentation and continuously with cell growth in liquid fermentation. ln liquid fermentation, fibrinolysin activity reached 645.Ouk.u/ml in the glucose compound medium adding 0. 7% Tryptone and 0. 1% Tweeri4O.