RESULTS, DISCUSSION, AND CONCLUSION
Figure 3. The oxygen uptake rate (OUR) calculated from the heat removal data as compared to the measured OUR
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As shown in the comparative OUR plot (Figure 3), the values calculated from the heat removal information follow the data gathered
using a mass spectrometer. They may not exactly match, but they are close enough from a comparative standpoint. The heat-generated
OUR data allow a researcher to understand the metabolic state of a process, and show what the peak OUR values are likely to
be. The data can be further defined using more exacting flow measurements and coolant flow control. For the above example,
much of the noise that enters the heat removal data pool stems from the flow fluctuations that result from the pulses of coolant
into the recirculating fluid in the jacket or coils of the fermenter. The secondary value of such heat removal OUR data lay
with the corroboration of other OUR calculation methodologies. If a mass spectrometer is normally used to calculate OUR values,
the data can be verified by the heat removal for the fermenter. The heat removal information adds an important data set for
scale-up purposes.
Mark Berge is a scientist, Swapnil Bhargava is a senior scientist, Radu Georgescu is an associate scientist, and Xiaoming (Jerry) Yang is scientific director, all at Amgen, Inc., Thousand Oaks, CA, 805.313.6362, mberge@amgen.com
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1. Cooney CL, Wang DIC, Mateles RI. Measurement of heat evolution and correlation with oxygen consumption during microbial
growth. Biotechnol Bioeng. 2000 Mar 20;67(6):691–703.
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3. Lydersen B, D'elia N, Nelson K. Bioprocess engineering: systems, equipment, and facilities. Hoboken, NJ: John Wiley &
Sons Inc.; 1994.
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