Saccharomyces cerevisiae, commonly known as baker's yeast, is a single-celled eukaryote and the first domesticated fungus. It has a globular shape and lives primarily on sugars, fermenting glucose to ethanol and carbon dioxide. S. cerevisiae has 16 chromosomes and is used traditionally in baking, brewing, and winemaking due to its carbon dioxide production. Modern applications include metabolic engineering, production of biopharmaceuticals, and use as a cell factory for industrial chemicals.

2. HAWASSA UNIVERSITY
12/19/2018 2
MSc : clinical laboratory ( special truck diagnosis and
public health microbiology)
Course : microbial genetics
Lecturer : Moges Desta (PhD)
by : Abdikhaliq Hussein Ali

3. Learning Objectives
At the end of this module, participants will be able to:
Discuss the importance of the overview of Saccharomyces cerevisiae
Describe general features and genetic makeup of Saccharomyces
cerevisiae
Applications of Saccharomyces cerevisiae

4. Outline
 Introduction of Saccharomyces cerevisiae
 Genetic makeup of Saccharomyces cerevisiae
 Application of Saccharomyces cerevisiae
 Summery

5. Introduction to Saccharomyces cerevisiae
• Saccharomyces cerevisiae is (commonly known as baker’s
yeast) is a single-celled eukaryote. More specifically, it is a
globular-shaped, yellow-green yeast belonging to the Fungi
kingdom
• Other names of Saccharomyces cerevisiae :
• Brewer's yeast
• Ale yeast
• Top-fermenting yeast
• Baker's yeast
 First species domesticated by humans
 Called baker’s yeast (or brewer’s yeast)
 Ferments glucose to ethanol and carbon dioxide

6. Introduction
• S. cerevisiae has developed as a model organism for
studies of biochemistry, genetics, molecular and
cell biology because it scores favorably on a number
of these criteria:
rapid growth rate
easy to modify genetically
features typical of eukaryotes
relatively simple (unicellular)
relatively small genome

7. taxonomical Classification
• Domain: Eukarya
• Kingdom: Fungi
• Subkingdom: Dikarya
• Phylum: Ascomycota
• Subphylum: Saccharomycotina
• Class: Saccharomycetes
• Order: Saccharomycetales
• Family: Saccharomycetaceae
• Genus: Saccharomyces
• Species: Cerevisiae

8. General characteristics of Saccharomyces cerevisiae
• S. cerevisiae lives primarily on fruits, flowers and
other sugar containing substrates
• Free-living organism: yeast copes with a wide range of
environmental conditions:
 S. cerevisiae proliferate from 12°C to 40°C
Growth is possible from pH 2.8-8.0
Almost complete drying is tolerated (dry yeast)
 S. cerevisiae can still grow and ferment at sugar
concentrations of 3M (high osmotic pressure)
Yeast can tolerate up to 20% alcohol
S. cerevisiae have both a stable haploid and diploid state

10. Genetic makeup of S. cerevisiae

11. Genetic makeup of S. cerevisiae
 S. cerevisiae has two vegetative stages, haploids and diploids.
 This allows generating mutations/mutants in haploids and study the
consequences of such mutations directly.
 Furthermore, mutations can be allocated to genes by
complementation in diploids heterozygous for a mutation.
 Genetic relationship can be studied directly in the haploid progeny of
meiosis: gene mapping and functional relationship of different genes.
 Those were main features making yeast a model in the pre-genomic
era, i.e. can 1960-1990.

12. The lifecycle of S. cerevisiae

13. Haploid
Mitosis
13

14. Diploid
Mitosis
14

15. Diploid
Mitosis
Haploid
Mitosis
15

16. Pathogenicity
• Saccharoyces cerevisiae is not normally
considered to be a pathogen. In healthy people,
disease resulting from S. cerevisiae colonizing in a
particular area are very rare, but have been
reported.
• 1% of all vaginal yeast infections occur due to S.
cerevisiae in the vagina
• immunosuppressed individuals, followed by
those who have taken S. cerevisiae as an
probiotic for diarrhea

18. Traditional applications
• Brewing: Saccharomyces cerevisiae is used in
brewing beer, when it is sometimes called a
top-fermenting or top-cropping yeast.

19. applications
• Baking (Baker's yeast )
S. cerevisiae is used in baking; the carbon dioxide
generated by the fermentation is used as a leavening
agent in bread and other baked goods.

20. applications
• Baking (Baker's yeast )
S. cerevisiae is used in baking; the carbon dioxide
generated by the fermentation is used as a leavening
agent in bread and other baked goods.

21. modern applications
• The yeast Saccharomyces cerevisiae is a key
cell factory already used for the production of
a wide range of industrial products.
Metabolic Engineering in Saccharomyces cerevisiae
Biopharmaceuticals
Agricultural and Biocontrol Applications
Environmental Applications
Biocatalysis and Fine Chemicals

22. Representative Commercial Recombinant Protein Pharmaceuticals and
Vaccines Produced in Yeasts (Johnson & Echavarri-Erasun, 2011)

25. summery
Saccharomyces cerevisiae is (commonly
known as baker’s yeast) is a single-celled
eukaryote. More specifically, it is a globular-
shaped, yellow-green yeast belonging to the
Fungi kingdom
First species domesticated by humans
Called baker’s yeast (or brewer’s yeast)
Ferments glucose to ethanol and carbon
dioxide

26. summery
• S. cerevisiae lives primarily on fruits, flowers
and other sugar containing substrates
The S. cerevisiae nuclear genome has 16
chromosomes.
In addition, there is a mitochondrial genome
and a plasmid, the 2μ circle.
The yeast chromosomes contain centromeres
and telomeres, which are simpler than those
of higher eukaryotes.

27. summery
Traditional applications
 Baking (Baker's yeast )
 Wine making
 Baking (Baker's yeast )
Modern applications
 Metabolic Engineering in
Saccharomyces cerevisiae
 Biopharmaceuticals
 Agricultural and Biocontrol
Applications
 Environmental Applications
 Biocatalysis and Fine
Chemicals
The yeast Saccharomyces cerevisiae is a key cell factory already
used for the production of a wide range of applications include:

28. References
• Ageitos, J.M., Vallejo, J.A., Veiga-Crespo, P., Villa, T.G., 2011. Oily yeasts as
oleaginous cell factories. Appl. Microbiol. Biotechnol., 90(4):1219-1227.
• Buijs, N.A., Siewers, N., Nielsen, J., 2013. Advanced biofuel production by the yeast
Saccharomyces cerevisiae, Current Opinion in Chemical Biology, 17: 480-488.
• Mustafa Türker, Pakmaya . April ,2014 Yeast Biotechnology: Diversity and
Applications publication at https://www.researchgate.net/publication/285598626
• Straathof, A.J.J., Panke, S. and Schmid, A.; The production of fine chemicals by
biotransformations, Current Opinion in Biotechnology 2002, 13:548–556.
• Wikipedia
https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae#In_commercial_applicati
ons