Kingdom Fungi By Dr.Ghasoun M.Wadai

Characteristics of Fungi Non-motile eukaryotes lacking chlorophyll Contain nucleus, mitochondria, 80S ribosomes Cell wall is composed of polysaccharides , polypeptides and chitin and the cell membrane contains sterol which prevent many antibacterial antibiotics being effective against fungi. Larger than bacteria Relatively simple nutritional requirements, wide range of growth rates Form visible colonies in days to weeks Unicellular or multicellular depending on the species Fungi can be divided into: Yeast, Mould (filamentous fungi) and Dimporphic fungi

Nutrition Fungi are heterotrophs obtaining nutrients by absorption. (They CANNOT make their own food like plants can with photosynthesis.) a. Fungi are either: Parasites—obtain nutrients from living organisms Decomposers—(or saprophytes) obtain nutrients from dead organisms b. Obtain nutrition by releasing digestive enzymes on organic matter to break it down, then the fungi absorbs the nutrients.

Nutrition C. Many fungi live symbiotically with plants or animals. For example, most trees have fungi living in close contact with their roots. In this relationship, known as a mycorrhiza, there are many benefits: Growing around the plant roots and often entering plant cells, the hyphae absorb minerals from the soil and release them in the roots. The fungi gets its source of food (organic nutrients) while delivering food to the plant. The mycelium here would increase the surface area, thus the absorptive surface, of the plant roots. The fungal cells help to maintain air and water flow in the soil around the roots. The fungi may prevent other potentially pathogenic fungi to attack the tree.

Fungi are plant-like because they CANNOT move about. Few fungi are unicellular but MOST are multicellular (many celled organisms). All fungi are eukaryotic (Eu = True) having a distinct nucleus. All have cell walls made mostly of the carbohydrate chitin, unlike cell walls of plants which are made mostly of (cellulose). Chitin is found in the exoskeleton of insects.

Fungi can be classified into four groups according to their morphology: - Mold – Mould - Yeast: Yeast-like fungi Dimorphic fungi

Molds Multicellular, tubular structures (hyphae) Hyphae can be septate (regular crosswalls) or nonseptate (coenocytic) depending on the species (grow by apical extension) Vegetative hyphae grow on or in media (absorb nutrients); form seen in tissue, few distinguishing features Aerial hyphae contain structures for production of spores (asexual propagules); usually only seen in culture

Molds - identification Identification based on colony morphology (pigment, texture) and morphology of reproductive structures Conidia - spores formed by budding (blastoconidia) or disarticulation of existing hypha (arthroconidia) Sporangiospores - produced by free-cell formation within sporangium in nonseptate molds 1 1 Conidiopspores Phialides Vesicle Conidiophore Septate hyphae 3 sporangium sporangiophore Endospores Nonseptate hyphae 5. rhizoids 2 3 4 2 5 4 5