Is it true that microorganisms are a source of antibiotics?

Microorganisms such as bacteria and fungi are major sources of antibiotics. Many soil microorganisms produce antibiotics naturally as part of their metabolic processes, as a defense mechanism against other microorganisms or to compete for resources. Researchers have identified and isolated numerous antibiotic compounds from microorganisms, such as penicillin from the Penicillium mold and streptomycin from the bacterium Streptomyces. Antibiotics are widely used to treat and prevent bacterial infections in humans and animals and are an important tool in modern medicine.