Actinomycetes

Actinomycetes is a class of bacteria within the phylum Actinomycetota, formerly known as Actinobacteria, a diverse group of Gram-positive bacteria with unusually high guanine-cytosine content in their DNA, in some cases reaching about 70 percent. Members inhabit both terrestrial and aquatic environments and play a major role in soil ecosystems by decomposing organic matter. The genus Streptomyces, a member of this class, is a major natural source of antibiotics used in human medicine, while Bifidobacterium is among the most common bacteria in the infant human gut. The class includes both some of the largest known bacterial cells and, among the marine Actinomarinales, some of the smallest known free living prokaryotes.