Practical mycology Division : Eumycota Subdivision: Zygomycotina Class: Zygomycetes Edited By Assistant prof: Murooj Alwash Assistant lecturer: Dalal Mohammed Division : Eumycota Subdivision: Zygomycotina Class: Zygomycetes The class zygomycetes derives its name from the thick-walled resting spores, the zygospores formed as a result of the complete fusion of the protoplasts of two equal or unequal gametangia. It comprises 450 species which are grouped under 70 genera. They all are terrestrial molds which show a wide range in their habit. Most of them are saprobes. Among these some are soil saprophytes and others coprophilous (growing on dung). Economically the zygomycetes are of significant importance. Some of them are used in the fermentation of food items while a few others are employed to produce enzymes, acids, etc. Saprophytic species spoil our food stuffs. Some zygomycetes are important mycorrhizal fungi and a few others are human pathogens. Distinctive Features of Zygomycetes: 1. The hyphal walls are chiefly composed of chitosan. 2. The motile cells are completely absent in the life cycle. 3. Asexual reproduction typically takes place by means of non-motile sporangiospores commonly produced in large numbers within sporangia. Sometimes the entire sporangium functions as a single spore in the same manner as the conidium. 4. Chlamydospore formation is of frequent occurrence. 5. Sexual fusion involves gametangial copulation. 6. The thick-walled sexually produced zygospore formed by the complete fusion of the protoplasts of two gametangia is a resting structure. 7. The zygospore germinates to produce a hypha, the promycelium which bears a terminal sporangium. Classification of Zygomycetes: Order Entomophthorales: 1-Typically parasitic on animals; rarely saprophytes. 2- Mycelium- limited. 3- Asexual reproduction by sporangia turned conidia or true conidia. 4- Gametangial wall not transformed to Zygospore wall. Order Zoopagales: 1-Typically parasite on animals, rarely saprophytes. 2- Mycelium present with complicated haustoria. 3- A sexual reproduction by conidia which are passively discharged. 4- Gametangial wall not transformed to Zygospore wall. Order Mucorales: 1- Chiefly Saprophytes, some weak parasites on plants, a few endoparasites of vertebrates. 2- Mycelium extensive. 3- Asexual reproduction by sporangiospores or rarely by conidia. 4- Zygospore wall may be formed by modification of gametangial walls. CLASS: Zygomycetes Order: Mucorales Family: Pilobolaceae Genus: pilobolus Pilobolus also called hat-thrower fungus, a cosmopolitan genus of at least five species of fungi in the family Pilobolaceae (order Mucorales) that are known for their explosive spore dispersal. Pilobolus species feed saprobically on the feces of grazing animals. These fungi are diminutive, usually less than 10 mm (0.4 inch) in height, and are characterized by a sparse mycelium (fungal body) that produces unbranched sporangiophores (fruiting bodies) capped with black sporangia (spore clusters). CLASS: Zygomycetes Order: Mucorales Family: Mucoraceae Genus: Mucor Mucor species produce nonapophysate sporangia that have a wet or dry wall when mature. The sporangia are more or less globose and all of the same type. The sporangiophores are simple or branched and they arise directly from the substrate; stolons and rhizoids are not formed. Class: Zygomycetes Order: Mucorales Family: Mucoraceae Genus: Rhizopus Species: Rhizopus stolonifer Rhizopus stolonifer is commonly known as black bread mold. It is characterized by the formation of apophysate sporangia with an evanescent wall that reveals a dry, grayish, spore-mass with surface cracks at maturity. When the fungus is mounted in liquid the relatively large columella collapses over the apex of the sporangiophore. Stolons and rhizoids are produced and the sporangiophores only arise opposite the rhizoids. .