ISSN:
0006-3592
Keywords:
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred-tank and in single- and ten-stage airlift tower reactors with an outer loop. The maximum specific growth rate, μm, the substrate yield coefficient, Yx/s, the respiratory quotient, RQ, substrate conversion, Us, the volumetric mass transfer coefficient, KLa, the specific interfacial area, a, and the specific power input, P/VL, were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both μm and YX/S, which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred-tank reactors, cannot be employed for tower-loop reactors: μm is higher in the stirred-tank batch than in the tower-loop batch reactor, μm and Yx/s are higher in the continuous reactor than in the batch single-stage tower-loop reactor. The performance of the single-stage is better than that of the ten-stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, Us, Pr, and YX/S and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, ds, remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces kLa. The specific power input, P/VL, for the single-stage tower loop is much lower with the same kLa value than for a stirred tank. The relationship kLa vs. P/VL evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.
Additional Material:
17 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260250210
