Fungi

Introduction

Fungi are a group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separate from other life forms such as plants, animals, and bacteria. The discipline of biology devoted to the study of fungi is known as mycology, which often is regarded as a branch of botany, even though genetic studies have shown that fungi are more closely related to animals than to plants.

A close-up image of a group of mushrooms in a forest. The mushrooms are brown and white, with a cap and stem structure. The forest floor is covered in leaves and moss.

Characteristics

Fungi are characterized by non-motile bodies (thalli) constructed of hyphae – long, filamentous structures with rigid cell walls. Unlike plants, fungi do not photosynthesize, and most are multicellular heterotrophs, feeding off organic material. They reproduce both sexually and asexually, often through spore dispersal.

Classification

The classification of fungi has been a subject of debate for many years. The five true phyla of fungi are the Chytridiomycota (Chytrids), the Blastocladiomycota, the Glomeromycota, the Ascomycota (Sac fungi or Ascomycetes), and the Basidiomycota (Basidiomycetes). There are also several groups of fungi that are not classified within a phylum but are likely to be related to the true fungi and have been described as the fungus-like organisms.

Ecology

Fungi play a vital role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange. They have long been used as a direct source of food, such as mushrooms and truffles, as a leavening agent for bread, and in fermentation of various food products, such as wine, beer, and soy sauce.

Pathogenic fungi

Fungi can cause a number of life-threatening diseases in humans, several of which may be fatal if untreated. These include aspergillosis, candidiasis, histoplasmosis, and pneumocystis pneumonia. Fungi are also the cause of athletes foot and ringworm. They can also cause damage to agricultural crops.

Economic importance

The economic importance of fungi is related to their roles in causing disease in crops and in humans, as well as their use in the production of food and drink. Some fungi, especially yeasts, are important "model organisms" for studying problems in genetics and molecular biology.