Saccharomyces cerevisiae

A detailed information about saccharomyces cerevisiae

1. BY:
CHARTHA.GAGLANI
BIOLOGY OF
SACCHAROMYCES
CEREVISIAE

2. CONTENTS
1)What is an organism?
2)What is Fungus?
3)What is yeast?
4)What is Saccharomyces cerevisiae?
5)Scientific classification
6)Habitat
7)Nutritional requirements
8)Reproduction
9)Brewer’s yeast
10)Baker’s yeast
11)Fungemia

3. Inbiology,anorganismis
anindividualentitythat
exhibitsthepropertyoflife.
Itisasynonymof'Life
Form’.

5. Thestudyoffungiiscalledmycology.
Likeanimals,humansandmostbacteria,
allfungiareheterotrophs.
Afungusisaeukaryoticorganism.
Yeasts,mouldsandmushroomsare
examplesoffungi.
Somemicroscopicfungi,forexample
yeast,areusedinthefoodanddrink
industrytoproducebread,beerandwine.
Candida albicans,Aspergillus
fumigatusandCryptococcusneoformans
arethefunguswhicharepathogenicto
humans.

7. Yeastsareeukaryotic,singlecelled
microorganismsclassifiedasmembersof
thefunguskingdom.
Thefirstyeastoriginatedhundredsof
millionsofyearsago,and
1,500speciesarecurrentlyidentified.
Yeastsizesvarygreatly,dependingon
speciesandenvironment,typically
measuring3–4µmindiameter,although
someyeastscangrowto40µminsize.

8. •Saccharomycescerevisiaeisaspeciesofyeast.Ithasbeen
instrumentaltowinemaking,baking,andbrewingsince
ancienttimes.
•Itisoneofthemostintensivelystudiedeukaryoticmodel
organismsinmolecularandcellbiology.
•Itisthemicroorganismbehindthemostcommontypeof
fermentation.S.cerevisiaecellsareroundtoovoid,5–10μm
indiameter.
•Itreproducesbyadivisionprocessknownasbudding.

10. Kingdom: Fungi
Phylum: Ascomycota
Subphylum:Saccharomycotina
Order: Saccharomycetales
Family: Saccharomycetaceae
Genus: Saccharomyces
Species: S.cerevisiae

11. •In nature, yeast cells are
found primarily on ripe
fruits such as grapes (before
maturation, grapes are
almost free of yeasts).
•The optimum temperature
for growth ofS. cerevisiaeis
30–35°C.

12. All strains of S. cerevisiae can grow aerobically on glucose,
maltose, trehalose.
Galactose and fructose are shown to be two of the best
fermenting sugars.
Yeastsalso have a requirement forphosphorus and some metals,
likemagnesium,iron,calcium, andzinc, are also required for good
growth of the yeast.
Concerning organic requirements, most strains ofS.
cerevisiaerequirebiotin.

14. The buddingyeast
Saccharomycescerevisiae
reproducesbymitosisas
diploidcellswhennutrients
areabundant,butwhen
starved,thisyeastundergoes
meiosistoformhaploid
spores.Haploidcellsmay
thenreproduceasexuallyby
mitosis.

15. Saccharomyces cerevisiae is used in
brewing beer, when it is sometimes called a
top-fermenting or top-cropping yeast.
It is so called because during the
fermentation process its hydrophobic
surface causes the flocs to adhere to CO2
and rise to the top of the fermentation
vessel.
Lager yeast normally ferments at a
temperature of approximately 5 °C (41 °F),
where Saccharomyces cerevisiae becomes
dormant.

18. S.cerevisiaeisusedinbaking;thecarbondioxide
generatedbythefermentationisusedasaleavening
agentinbreadandotherbakedgoods.
Preparingyeastsbreadsrequiresthedevelopmentof
glutenandformationofCO2.
Theglutendevelopsduringmixingandkneading,the
glutenwillformtheframeworkofbreadandholdthe
CO2producedbyyeastduringfermentation.
TheyeastwillproduceCO2whichwillgivevolumeto
thebread.

20. •Fungemiaorfungemiaisthepresenceoffungioryeastsinthe
blood.Themostcommontype,alsoknownascandidemia,caused
bySaccharomyces,AspergillusandCryptococcus,arealsocalled
fungemia.
•Symptoms:includespain,acuteconfusion,chronicfatigue,and
infections.Skininfectionscanincludepersistentornon-
healingwoundsandlesions,sweating,itching,andunusual
dischargeordrainage.
•Treatment:An intravenousechinocandinsuchas
anidulafungin,caspofunginormicafunginisrecommendedasfirst-
linetherapyforfungemia,specificallycandidemia.Oralor
intravenousfluconazoleisanacceptablealternative.