S. cerevisiae, a.k.a. The best domesticated species since the dog
Saccharomyces cerevisiae is a fungus, a very particular one, part of a group of fungi called yeasts that also includes species responsible for Candidiasis, Cryptococcosis and pretty much every food spoilage.
If you think fungi are all gross, you're very mistaken because you've most likely eaten and drunk S. cerevisiae corpses and their biologic wastes several times in your life (and probably, you've asked for seconds many times)
I have eaten a fungus? Where?
S. cerevisiae has been used in many applications (mostly food) in the past few millenia. You may know it by one of its other names:
- Brewer's yeast, though other species are also used in brewing
- Ale yeast
- Top-fermenting yeast
- Baker's yeast
- Budding yeast
Which means that you've tasted little ol' S. c. pretty much every time you've consumed something baked or fermented, mostly wine, beer and bread1. It's also available in the form of Marmite or Vegemite, as well as several nutritional supplements (yeast extract is a source of Vitamin B12)
Is that all?
cerevisiae's use in foods is only the top of the iceberg. In the past decades, it's also been used extensively in almost every field involving microbiology because it's a model organism. Its most attractive features for research are:
- It grows easily and can be cultured with several carbon sources
- Short generation time. Under ideal conditions (30°C / 86°F) it can double its numbers every 2 hours
- It's a eukaryote, which means that it shares the internal cell structure of all bigger species including humans. It has the advantage of having a relatively low percentage of non-coding DNA, which allows for easier genetic analyses
- Its genes can be easily transformed (added or deleted)
- It's accessible, easy to find and has minimal (if any) health risks
These make C.s. a great organism for teaching/researching topics such as reproduction, general genetics, DNA replication, DNA damage and repair mechanisms, genetic expression, aging, genetic interactions, protein interactions and even testing whether some life forms can survive in space2.
- S. cerevisiae was the first eukaryotic genome to be completely sequenced
- Most people I know say that you either love Marmite or hate it. I've yet to prove or disprove this statement, but generations of british people seem to confirm it.
- For many homebrewing processes, "wild" strains of S.c. can be found in unwashed plums and grapes. Look for a thin whitey layer.
- S.c. can grow as both a haploid or a diploid (in layman's terms, it han have n or 2n chromosomes)
1Beer and bread in particular are an interesting pair, being two of the oldest cooked foods in the history of mankind. If we reduce them to their oldest, most basic processes, they're pretty much the same thing: bread is like solid beer and/or beer is liquid bread
2That last one is still a mystery. The last time someone tried to test it, it had technical problems. See: Living Interplanetary Flight Experiment