"Actinomyces" species are , occurring in soil and in the microbiota of animals, including the human microbiota. They are known for the important role they play in soil ecology; they produce a number of enzymes that help degrade organic plant material, lignin, and chitin. Thus their presence is important in the formation of compost. Certain species are commensal in the skin flora, oral flora, gut flora, and vaginal flora of humans and livestock. They are also known for causing diseases in humans and livestock, usually when they get an opportunity to gain access to the body's interior through wounds. As with other opportunistic infections, people with immunodeficiency are at higher risk. In all of the preceding traits and in their branching filament formation, they bear similarities to "Nocardia".