Penicillium (from Latin penicillus: paintbrush) is a genus of ascomycetous fungi of major importance in the environment, food and drug production. It produces penicillin, a molecule that's used as an antibiotic, which kills or stops the growth of certain kinds of bacteria inside the body. Characteristics The thallus, (mycelium) typically consists of a highly branched network of multinucleate, septate, usually colorless hyphae. Many-branched conidiophores sprout on the mycelia, bearing individ… (More on Penicillium)