Which bacterium causes diphtheria-like disease in some animals and produces the antibiotic erythromycin?

Saccharopolyspora erythraea produces the antibiotic erythromycin and was formerly classified as Streptomyces erythreus.

This filamentous bacterium belongs to the actinomycetes, a broad group of soil-dwelling organisms that often form branching structures resembling fungal hyphae. Researchers discovered erythromycin in a soil sample collected in the Philippines in the early 1950s. The compound became an important alternative for people who could not take penicillin and remains a member of the macrolide antibiotic family.

The species was originally placed in the genus Streptomyces, but later taxonomic work moved it to Saccharopolyspora. Its name reflects its characteristic spore-bearing structures and its relationship to sugar-containing compounds. Industrial fermentation is used to produce erythromycin and related derivatives.

A common mistake is attributing erythromycin to Streptomyces griseus, the organism associated with streptomycin. These bacteria are both antibiotic producers, but they make different drugs. Saccharopolyspora erythraea is also not the bacterium that causes human diphtheria; that disease is caused by Corynebacterium diphtheriae.