Producing proteins on a large scale 2 Flashcards
(36 cards)
What are the main stages of cell culture growth?
Lag phase, Exponential phase, stationary phase, decline phase
Cell growth is considered a ‘what’ order reaction
first order reaction
In the equation
Generation = muX what do the variables represent?
mu = Specific cell growth rate X = the number of cells
What is the Monod kinetic formula?
mu = (mumax*X)/(Ks+S)
What is mumax?
maximum specific growth rate – represents the cells in exponential phase
What is Ks?
The growth- limiting substrate concentrations to give half the µmax
What are the axis of the double reciprocal linear graph used to show monod kinetics?
x - 1/S
Y - 1/mu
In the lineweaver burk plot what are the intercepts?
X - -1/Ks
y - 1/mumax
In the context of cells what is consumption?
Cell death
comsumption = KdX
no cell death is assumed in exponential or lag phase (in batch)
and through continuous reactor
In the context of cell what is Kd?
The death constant
If your product is under a constitutive promoter is the product production growth associated?
Yes
If your product is under a inducible promoter is the product production growth associated?
no - non-growth associated promoter
What is the Leudeking-piret formula?
Generation = alphamuX + betaX
With a constitutive promoter what equals zero:
a) alphamuX
b) betaX
betaX
- growth associated
How do you determine Yx/s, Yp/s and Ms?
Determined by plotting graphs
Yx/s - gradient of X/S graph
Yp/s - gradient of P/S graph
Ms - Qs/mu graph extrapolated back to the y axis
What is Qs?
specific utilisation of substrate
What scale production might you use a batch reactor for?
Small Scale Production
What are the limitations of a batch reactor?
Expensive because of downtime
Inhibition due to high conc of things cells produce e.g. lactate
What cells are often cultured in fed (semi-) batch reactors?
Mammalian cells
In fed batch the amount of what stays roughly constant?
Substrate
In continuous stirred tank reactors what are the benefits?
Constant productivity
Steady state physiology
Control cell growth rate via dilution
In what type of bioreactor is there a sensors to ensure that the volume that enters the tank is the same as that leaves the tank?
Continuous stirred tank reactor
What is the principle of an airlift reactor?
Uses airflow to promote mixing.
Air dissolves in medium which get less dense, rises, bubbles burst, gets more dense, sinks
What is the benefit of a airlift reactor?
No moving parts Easy to maintain sterility Allows a large volume Low energy input Low shear
