Sordaria fimicola

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Sordaria fimicola
Scientific classification
Kingdom: Fungi Phylum: Ascomycota Class: Ascomycetes Order: Sphaeriales Family: Sordariaceae Genus: Sordaria Species: S. fimicola
Binomial name
Sordaria fimicola (Roberge ex Desm.) Ces. & De Not.

Sordaria fimicola is a species of microscopic fungus. It is commonly found in the feces of herbivores. S. fimicola is often used in introductory biology and mycology labs because it is easy to grow on nutrient agar in dish cultures. The genus Sordaria, closely related to Neurospora and Podospora, is a member of the numerous class Pyrenomycetes or flask-fungi. The natural habitat of the three species of Sordaria that have been the principal subjects in genetic studies is dung of herbivorous animals. The species S. fimicola is common and worldwide in distribution. The species of Sordaria are similar morphologically, producing black perithecia containing asci with eight dark ascospores in a linear arrangement. These species share a number of characteristics that are advantageous for genetic studies. They all have a short life cycle, usually 7-12 days, and are easily grown in culture. Most species are self-fertile and each strain is isogenic. All kinds of mutants are easily induced and readily obtainable with particular ascospore colour mutants. These visual mutants aid in tetrad analysis, especially in analysis of intragenic recombination.

The most common form of S. fimicola is a dark brown. Certain mutants are grey or tan. A common experiment for an introductory lab class is to cross one of the mutant types with a wild type and observe the ratio of coloring in the offspring. This experiment illustrates the concepts of genetic inheritance in a haploid organism. The eight ascospores are produced inside an ascus. Soradia squashes can give us information about crossing over during meiosis. If no crossing over then there is a 4:4 pattern. 4 black spores, and 4 tan spores all lined up. If crossing over does occur there is a 2:2:2:2 pattern visible, or a 2:4:2 pattern.

Another common lab use is to observe meiosis and mitosis in the fruiting bodies, called perithecia. An interesting feature of S. fimicola is that its fruiting body is phototrophic. Thus, as it grows the stalk will bend toward a light source and when the sac bursts, the spores are shot towards the light.

This species is officially used by the college board for AP Lab 3: Mitosis and Meiosis for the Advanced Palacement (AP) class AP Biology for high schools to earn college credit. It is specifically used in Exercise: 3B.2.