KEY CONCEPT Fungi recycle nutrients in the environment.

Fungi may be decomposers, pathogens, or mutualists. Fungi and bacteria are the main decomposers in any ecosystem. decompose dead leaves, twigs, logs, and animals return nutrients to the soil Called saprobes (they eat dead stuff)

Fungi can act as pathogens. Some always cause disease Others cause disease when a change in homeostasis gives fungi a chance to grow. Corn smut

Fungi can act as pathogens. human diseases include ringworm and athlete’s foot Extra moisture Sometimes overuse or incorrect use of antibiotics cause fungal infections Yeast infections

ringworm Athlete’s foot

Fungi can act as pathogens. May damage fruit trees and wooden structures Plant diseases include Dutch elm disease Rusts Smuts Blights Elm bark beetles burrow into Dutch Elm trees and spread the fungus

Ergot Fungus on wheat Causes hallucinations and erratic behavior May have been the cause during the Salem Witch Trials, Salem, Mass. 1692

Fungi can act as mutualists. Mutualism: a relationship between 2 organisms where both benefit. lichens form between fungi and algae Fungi are the home Algae (or cyanobacteria) make the food

Fungi can act as mutualists. mycorrhizae form between fungi and plants Plants provide the home and food Fungi help the plants take up water and nutrients

Fungi can act as mutualists. relationships form between fungi and some insects

Fungi are studied for many purposes. Fungi are useful in several ways. as food as antibiotics as model systems for molecular biology