ThermoFisher Scientific HyPerforma DynaDrive - Sparging Issues

We are not achieving the cell growth we expected in the DynaDrive S.U.B.
while running under our normal bioreactor agitation and sparging rates.
What should we do?
Reduce agitation and sparging rates.
• Often low cell viability and cell growth can be attributed to excessive sparging or
agitation. We recommend that you reduce the sparge rate compared to what you
might use in a conventional bioreactor. Gas flow rates supplied as overlay should also
be reduced as much as possible. Too much gas creates excess foam and higher
shear conditions. Provide only the level of agitation needed (low viability and lysed
cells), reduce agitation speed (cell aggregation and settling), and increase agitation.
• Media formulation can also have a significant eect on cell culture growth in the
DynaDrive S.U.B. Surfactants such as Pluronic
™
decrease shear and increase
kLa, but at a cost of increased foaming. Thermo Scientific can oer custom media
especially for the S.U.B. and your specific cell line(s).
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Chapter 5 | Troubleshooting and frequently asked questions
5.3. Sparging issues
There is excessive foam in the bioreactor headspace.
Alter the liquid surface tension related to the culture media and/or sparge
gas.
• A media supplement of antifoam can be used in the DynaDrive S.U.B. These serve to
lower the surface tension of the media and will reduce the presence of foam.
• High sparge rates of air can result in the presence of excessive foam. Testing has
shown that sparging with oxygen will typically result in a dramatic reduction of foam
in the headspace.
The sparger does not seem to be working although gas is present.
Allow the sparger membrane to purge.
• If the DynaDrive S.U.B. is filled with liquid and allowed to sit idle for extended periods
of time without gas being supplied to the sparger, liquid can accumulate between
the membrane and check valve. Various media additives may restrict the membrane
temporarily. Several minutes of gas pressure being supplied to the sparger should
purge the membrane, allowing it to function properly.
• Certain operating conditions can create situations when the sparger membrane may
become restricted due to insucient line pressure from the bioreactor controller
gas feed line. Increasing the flow rate to one liter per minute, or momentarily raising
the pressure regulator outlet pressure to 0.34 bar (5 psi) may alleviate the problem.
Alternatively, several seconds at this higher pressure will allow the membrane to
purge pores that may be blocked due to the presence of accumulated liquid.
Thermo Scientific 61DynaDrive S.U.B. Service Guide