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Title: Application of macroscopic principles to microbial metabolism

Journal Article · · Biotechnol. Bioeng.; (United States)

General expressions for mass, elemental, energy, and entropy balances are derived and applied to microbial growth and product formation. The state of the art of the application of elemental balances to aerobic and heterotrophic growth is reviewed and extended somewhat to include the majority of the cases commonly encountered in biotechnology. The degree of reduction concept is extended to include nitrogen sources other than ammonia. The relationship between a number of accepted measures for the comparison of substrate yields is investigated. The stoichiometry of anaerobic product formation is briefly treated, a limit to the maximum carbon conservation in product is derived, using the concept of elemental balance. In the treatment of growth energetics the correct statement of the second law of thermodynamics for growing organisms is emphasized. Based on a literature review concerning yield data some semiempirical notions useful for a preliminary evaluation of aerobic heterotrophic growth are developed. The thermodynamic efficiency definition is completed by two other efficiency measures, which allow derivation of simple equations for oxygen consumption and heat production. A preliminary analysis shows the existance of regularities concerning the free energy conservation on anaerobic growth. The treatment is extended to include the effect of growth rate by the introduction of a linear relationship for substrate consumption. Aerobic and anaerobic growth are discussed using this relationship. A correlation useful in judging the potentialities for improvement in anaerobic product formation process is derived. Finally the relevance of macroscopic principles to the modeling of bioengineering systems is discussed.

Research Organization:
Lab for General and Technical Biology Dept of Chemical Engineering, Delft Univ of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
OSTI ID:
6747169
Journal Information:
Biotechnol. Bioeng.; (United States), Vol. 22:12
Country of Publication:
United States
Language:
English