In the stationary phase, do we add any sort of bacteria that causes fungus to adopt a defensive manner by producing penicillin or is it due to the deficiency of nutrients?

by Zehra

My ma'am told me that we add a bacteria , if so please tell me its name and clear me the idea. If bacteria is added in stationary phase, it isn't impossible because it's a batch fermenter that needs to be closed (I know fed batch fermenter can be used as well but i want to know about batch fermenter only).