Bioreactor system and method for operating biological process

A bioreactor system (1) for accommodating a disposable bioreactor bag (100) comprises an accommodating container (10) having a container wall (11), the container wall (11) defining an accommodating space (12) in which the disposable bioreactor bag (100) is accommodated in an operating state of the bioreactor system (1). A stirring system (14) extends at least partially into the accommodation space (12) and is designed and configured to stir a biological medium (101) present in the disposable bioreactor bag (100) in an operating state of the bioreactor system (1). At least one partition (30; 30 ') which reduces the receiving space (12) and which is different from the container wall (11); 40, 41, 42; 50; 60; 72; 73; 80); 81) for reducing the laminar flow of the biological medium (101). The at least one diaphragm (30; 40, 41, 42; 50; 60; 72; 73; 80); 81) is at least partially flowed through by a temperature control medium, which controls the temperature of the partition (30; 40, 41, 42; 50; 60; 72; 73; 80); 81)