Mucormycosis (previously called zygomycosis) is a serious but rare fungal infection caused by a group of molds called mucormycetes. These molds live throughout the environment. Mucormycosis mainly affects people who have health problems or take medicines that lower the body's ability to fight germs and sickness.Nausea and vomiting. Mucormycosis is caused by different kinds of fungi that are often found in decaying organic matter. These include spoiled bread, fruit, and vegetables, as well as soil and compost piles. Most people come in contact with the fungus at some time.