Penicillium notatum is a type of mold that belongs to the genus Penicillium. It is known for its role in the discovery of the antibiotic penicillin by Alexander Fleming in 1928. This mold typically grows on decaying organic matter and can be found in various environments, including soil and food. The spores of Penicillium notatum are greenish-blue and can reproduce rapidly under suitable conditions. This mold is important in biotechnology and medicine, as it has led to the development of antibiotics that treat bacterial infections, significantly impacting public health.