Zygomycetes are a kind of primitive, fast-growing and widely distributed terrestrial eumycetes, most of which exist in plant spoilage and soil. Many are common polluting bacteria in the environment, which can lead to food deterioration. A few are pathogenic bacteria of plants and insects, and a few can cause human diseases. These fungi reproduce sexually to produce zygospores, and asexually to form sporangium spores. Mycelium is multinucleated, most of which have no septa, so it is easy to distinguish it from other filamentous fungi. Zygomycetes, as a class, is considered to be a fairly natural (not artificially hard-divided) group. This classification is confirmed by the composition of chitosan and chitin in cell wall and recent molecular biology methods. Zygomycetes are composed of 7 orders and 30 families. But only Mucor and Insecta are of medical importance.

Pathogens of Gliocladiaceae include Rhizopus, Plough, Rhizopus, Mucor and Myxomycetes, as well as various fungi of Myceliaceae, Mortierella, Botrytis, Trichophyton and Cladosporiaceae. The pathogens of Insecta include Rana chensinensis in China, Auricularia coronata and Auricularia heterospora in Insecta. Rhizopus oryzae (different names: Rhizopus arrhizus) is the most common pathogen, accounting for about 60% of culture-positive cases and 90% of nasal and brain infections. Rhizopus oryzae is distributed all over the world, mostly in tropical and subtropical regions. It can be separated from soil, rotten vegetables, food, animals and bird droppings. In Indonesia, China and Japan, Rhizopus oryzae is often used to pickle food and alcoholic drinks. It can produce ergotoxine, a ergotoxine, which is toxic to people and animals.

Mucor is ubiquitous in nature and is an important spoilage bacteria of organic matter. Under normal circumstances, this kind of bacteria is non-toxic, and most infections occur in patients with serious basic diseases. The optimum growth temperature of Mucor is 28 ~ 30℃, and it can also grow at 37℃ when it is isolated. Mucor is characterized by thick mycelium, no separation or little separation; The hypha wall is thick, and the lateral branches are at right angles to the mother branches; Good invasion of blood vessels, easy to form thrombus in the cavity, resulting in local tissue necrosis. Pathogens of entomophilous bacteria usually exist in the gastrointestinal tract of decaying plants and many reptiles and amphibians, but they are not pathogenic to animals. This fungus has not been isolated from insects, but spores sometimes attach to insects and become vectors. This kind of bacteria is not hardy and will die quickly in a cold environment. This kind of bacteria can be isolated from tropical and subtropical environments. The strain grew well at 25 ~ 37℃, but it grew poorly at room temperature.