Biological fermentation process for generating the metabolic products of haemolytic streptococci, especially streptokinase. Streptokinase is a known thrombolytic agent which has become widely used in therapy. The process can be used in the pharmaceutical industry as long as industrial microbiology equipment is available. The process allows the generation of streptokinase in high yields of more than 8000 IU/ml of culture solution by cultivating haemolytic streptococci. An essential feature in this connection is that no costly additives such as growth promoters, vitamins, amino acids etc. are necessary for the nutrient solution when yeast autolysate and/or corn steep liquor with a N content of 0.1 to 0.8 % based on the culture solution is employed as nitrogen source. It is possible to admix yeast autolysate and corn steep liquor with other nutrient solutions based on peptone. The process can be carried out in 3 stages, i.e. 2 preculture stages and 1 main culture stage.
