dactylosporangium aurantiacum dactylosporangium aurantiacum dactylosporangium aurantiacum is a gram-positive soil-based actinobacterium in the family micromonosporaceae. like all dactylosporangium species, aurantiacum is aerobic and mesophilic. dactylosporangium aurantiacum scientific classification domain: bacteria phylum: actinomycetota class: actinomycetia order: micromonosporales family: micromonosporaceae genus: dactylosporangium species: d. aurantiacum binomial name dactylosporangium aurantiacumthiemann et al. 1967 (approved lists 1980) type strain atcc 23491dsm 43157ifo 12592jcm 3083nbrc 12592nrrl b-8018nrrl b-8111vkm ac-654 one subspecies, hamdenesis, produces a number of 18-membered macrolide antibiotics called tiacumicins as a byproduct of fermentation. one of these, tiacumicin b, commonly known as fidaxomicin, has narrow-spectrum bacteriocidal action against gram-positive anaerobic bacteria, including clostridium difficile.