Soil fungus and bacteria absorb these nutrients. This respiratory disease is caused by inhaling airborne spores of the fungus. Scalp skin can suffer from infestations of mites, lice, infections of the follicles or fungus. A number of species of fungus cause powdery mildew on oak species. Spores are the seeds of a fungus. It is a fixative, and kills bacteria, fungus, and insects. There are reference genomes for multiple species of viruses, bacteria, fungus, plants, and animals. The swelling occurs because of infection with the smut fungus "Ustilago esculenta". Sporotrichosis is a disease caused by the infection of the fungus "Sporothrix schenckii". Rye is highly susceptible to the ergot fungus. Roots of cacti can be eaten by the larvae of sciarid flies and fungus gnats. There is no cure or vaccine for the fungus. These are the distinguishing structures of arbuscular mycorrhizal fungus. Histoplasmosis is a disease caused by the fungus "Histoplasma capsulatum". The toxins present are secondary metabolites produced by the fungus.