Alexander fleming was a biologist who was best known for his discovery of the antibiotic penicillin. during his research, dr. fleming noticed that there was no bacterial growth where there was mold growing on his petri dishes. he could have thrown out his plates, but instead he cultured the mold. how did dr. fleming’s creativity lead to a scientific discovery? he noticed that bacteria cells and mold coexisted well. he observed that bacterial cells had become mold. he concluded that the mold inhibited the growth of bacteria. he inferred that mold and bacteria share most of their dna.