Conidiospores are formed on aerial hyphae called conidiophores. An example of a mold that produces sporangiospores is the bread mold, Rhizopus. The sporangia of specific molds have characteristic shapes which can be used to identify the mold. ![]() Sporangiospores are produced at the end of aerial hyphae called sporangiophores in a saclike structure called a sporangium. The two types of asexual spores produced by molds are called sporangiospores and conidiospores. Other hyphae, called aerial hyphae, grow above the agar surface and produce asexual reproductive spores. Some of the hyphae, called vegetative hyphae, grow on or down into the agar surface to extract nutrients from the medium. Hyphal filaments intertwined into a mass, known as mycelia, can be seen macroscopically as fuzzy or hairy, colorful colonies. The hyphal filaments not separated by cross walls are called aseptate or coencocytic hyphae. Most fungal hyphal filaments are separated by a cross wall and are called septate hyphae. Moldįungi that grow as mold produce multicellular filaments called hyphae. Examples of yeast include Candida albicans which is an opportunistic pathogen and Saccharomyces cerevisiae which is used to make bread. Biochemical tests, such as carbohydrate assimilation tests, must be performed to speciate yeast. Most yeast have similar macroscopic and microscopic appearances. Successive blastospores remaining attached to the original cell result in the formation of pseudohyphae. The blastospore may break off from the parent cell or stay attached. Yeast reproduce asexually by budding and the newly produced cell, called a bud or blastospore, protrudes from the periphery of the parent cell. Yeast cells are usually five to ten times larger than bacteria and can be visualized at 400X total magnification. Microscopically, yeast cells are unicellular and round to oval, whereas bacteria cells vary in shape (cocci, rods, spirals). ![]() The colonial appearance of most yeast is moist, creamy and white in color and similar in appearance to Staphylococcus colonies. Some fungi take three weeks or more to grow. Although some yeasts can grow at 36☌, we incubate all fungal cultures at 25 to 30☌ for at least one week. Sabouraud’s agar is selective media for fungi because it incorporates simple nutrients (glucose and peptone) at a pH of 4.5-5.6 which inhibits bacterial growth. Coccidioides immitis, the fungus responsible for San Joaquin Valley Fever, is an example of a dimorphic fungus.įungi grow slower than bacteria and at a lower temperature and lower pH than most bacteria prefer. However, there are some fungi that are dimorphic, meaning they can grow as yeast under certain environmental conditions (such as the warm moist lungs in the body) and mold under other conditions (such as in soil in the environment). Fungi are eukaryotic organisms which grow as either yeast or mold.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |