The first antibiotic discovered was penicillin. It was discovered in 1828 by Alexander Fleming when he noticed the growth of mold-fungus in the culture of Staphylococcus and there were no bacteria in the region where the fungus was growing. It was because the fungus was secreting the anti-biotic that had killed the bacterial cells in the culture. The fungus was recognized as Penicillium.
Terramycin is an antibiotic derived from Streptomyces rimosus, a species of actinomycete isolated from a soil sample. It is amphoteric and forms a hydrochloride and a sodium salt. Terramycin had a low degree of toxicity in animals and that the crystalline hydrochloride salt possessed a wide range of antibacterial activity against both Gram-positive and Gram-negative organisms