Thermodynamic analysis of product formation in mesophilic acidogenesis of lactose

Thermodynamic analysis on the acidogenesis of lactose was performed to evaluate the different acidogenic patterns and mechanisms by using Gibbs free energy calculation. Batch acidogenesis of lactose was investigated by using an enriched culture at 37°C, pH 5.5 and varied substrate levels. In additio...

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Bibliographic Details
Published in:Biotechnology and bioengineering 2004-09, Vol.87 (7), p.813-822
Main Authors: Yu, Han-Qing, Mu, Yang, Fang, Herbert H. P.
Format: Article
Language:English
Subjects:
acidogenesis
alcohols
Alcohols - metabolism
Bacteria, Anaerobic - metabolism
Biological and medical sciences
Bioreactors - microbiology
Biotechnology
Energy Metabolism - physiology
Fatty Acids, Volatile - metabolism
Fundamental and applied biological sciences. Psychology
Hydrogen-Ion Concentration
lactose
Lactose - metabolism
Methods. Procedures. Technologies
Microbial engineering. Fermentation and microbial culture technology
Models, Biological
Models, Chemical
Oxygen Consumption - physiology
Sewage - microbiology
thermodynamic
Thermodynamics
volatile fatty acids (VFA)
Water Purification - methods
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Summary:Thermodynamic analysis on the acidogenesis of lactose was performed to evaluate the different acidogenic patterns and mechanisms by using Gibbs free energy calculation. Batch acidogenesis of lactose was investigated by using an enriched culture at 37°C, pH 5.5 and varied substrate levels. In addition to usual acidogenic products, i‐butyrate, valerate, i‐valerate, caproate, and propanol were also produced at a significant level. Thermodynamic analysis shows that valerate might be formed through the reaction requiring hydrogen as electron donor and consuming of propionate and carbon dioxide. Caproate was most likely produced directly from butyrate, hydrogen, and carbon dioxide. The minimum amount of Gibbs free energies needed to sustain isomerization of butyrate and valerate were approximately 5.7–5.8 and 4.5–4.6 kJ/mol, respectively. Propanol was produced from acetate, hydrogen, and carbon dioxide with a minimum amount of Gibbs free energy of 41.8–42.0 kJ/mol. Formation of butanol was controlled more by substrate level or population dynamics than by thermodynamics. © 2004 Wiley Periodicals, Inc.
ISSN:0006-3592
1097-0290
DOI:10.1002/bit.20190