Chapter 12: Fungi, Algae, Protozoa, and Multicellular Parasites Fungi • Mycology = Study of Fungi • All Fungi are chemoheterotrophs – Require organic compounds for energy and carbon – Can be aerobic (filamentous, bread mold) or facultative anaerobes (yeast) • Most of the 100,000 or more fungal species are decomposers of dead plant material. – Very few organisms other than fungi have enzymes that can breakdown hard plant material (cellulose, lignin, pectins) • Only about 200 species are implicated in human disease. Table 12.1 Table 12.2 Fungi: Vegetative Structures (cells involved in catabolism and growth) – Multicellular fungi, unlike yeast identification, are identified on the basis of physical appearance, including colony characteristics and reproductive spores. – 1. Molds and Flesh Fungi • a. Thallus – long filaments of cells joined together (called hyphae). Color, consistency of growth. • b. Septa – cross-walls dividing the hyphae into distinct, uninucleate cell like units (called septate hyphae) • c. Vegetative hyphae – portion that is used to obtain nutrients (growthbelow surface of media) • d. Aerial hyphae – projects above media on which fungus is growing and often contains spores • e. Mycelium – filamentous mass Figure 12.1 - Overview Figure 12.2 - Overview Fungi: Vegetative Structures – 2. Yeasts • Nonfilamentous unicellular fungi that are spherical or oval • Some divide by fission that can either be even or uneven cell division (budding) • Candida albicans – sometimes produces buds that fail to detach into daughter cells and are called pseudohyphae. – These can resemble hyphae and penetrate deeper tissue. • Colonies on agar can resemble bacterial colonies, especially staph colonies. • Can use oxygen or organic compounds as final electron acceptor (can do aerobic respiration and fermentation) Figure 12.3 Figure 21.17: Candidiasis - Overview. Chlamydoconidia Pseudohyphae Blastoconidia (a) Candida albicans (b) Oral candidiasis, or thrush 20 mm