The Actinobacteria is a phylum of monoderm Gram positive bacteria, many of which are notable secondary metabolite producers. There are only two phyla of monoderm Gram positive bacteria, the other being the Firmicutes; the actinobacteria generally have higher GC content so are sometimes called high-CG Gram positive bacteria. Notable genera/species include Streptomyces (antibiotic production), Propionibacterium acnes (odorous skin commensal) and Propionibacterium freudenreichii (holes in Emmental).