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Microbialbiotechnologyinthelaboratoryandinpractce
C0Stabilisationofmicroorganismsbyimmobilisation
Materialsandmedia
1.Microorganism:Saccharomycescerevisiae.
2.Medium:wort12°Blgand8°Blg.
3.
Reagents:sodiumalginate,carrageenan,0.2Msolution
ofCaCl
2
.
Aimoftheexercise
Comparisonoffermentatoncapacityoffreeyeastcellsandyeast
immobilisedingels.
Procedure
1.ImmobilisationofS.cerevisiaecellsinalginate.
a)
Centrifugethe48-hshakenS.cerevisiaeculture
in12°Blgmaltwortfromthemedium,washwith
asolutionofsterilesalineandthencentrifuge
again.Thoroughlydisperseyeastprecipitatein
steriledistilledwater(in0.1originalvolume).In
theobtainedsuspension,counttheyeastcellsinthe
Thomachamberandgivetheirdensityper1mlofthe
immobilizate.Dividetheyeastprecipitateobtained
fromthecultureinto2equalparts;
b)preparea4%sterilesolutionofsodiumalginate;
c)mixtheyeastsuspensionwiththealginatesolutionat
avolumeratioof1:1;
d)
putthecellsuspensioninthealginateinasterile
syringewithaneedle1mmindiameterandacutend;
dropthesuspensionintothesterile0.2MCaCl
2
.Leave
thebeadsinsolutionfor20min.Washthehardened
beadstwicewithsteriledistilledwater;
e)placethebeadsinaflaskcontaining100mlof8°Blgof
maltwort;transfertheflasktoathermostatat28°C;
f)
carryoutanidenticalfermentationtestwithS.
cerevisiaefreecellsatthesameinitialdensity;
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