Metabolic energy-based modelling explains product yielding in anaerobic mixed culture fermentations

González-Cabaleiro, R. , Lema, J. M. and Rodríguez, J. (2015) Metabolic energy-based modelling explains product yielding in anaerobic mixed culture fermentations. PLoS ONE, 10(5), e0126739. (doi: 10.1371/journal.pone.0126739) (PMID:25992959) (PMCID:PMC4436308)

Abstract

The fermentation of glucose using microbial mixed cultures is of great interest given its potential to convert wastes into valuable products at low cost, however, the difficulties associated with the control of the process still pose important challenges for its industrial implementation. A deeper understanding of the fermentation process involving metabolic and biochemical principles is very necessary to overcome these difficulties. In this work a novel metabolic energy based model is presented that accurately predicts for the first time the experimentally observed changes in product spectrum with pH. The model predicts the observed shift towards formate production at high pH, accompanied with ethanol and acetate production. Acetate (accompanied with a more reduced product) and butyrate are predicted main products at low pH. The production of propionate between pH 6 and 8 is also predicted. These results are mechanistically explained for the first time considering the impact that variable proton motive potential and active transport energy costs have in terms of energy harvest over different products yielding. The model results, in line with numerous reported experiments, validate the mechanistic and bioenergetics hypotheses that fermentative mixed cultures products yielding appears to be controlled by the principle of maximum energy harvest and the necessity of balancing the redox equivalents in absence of external electron acceptors.

• Item Type: Articles
• Additional Information: This work was supported by Xunta de Galicia under a predoctoral grant (Plan I2C 2011/2015) to RG-C; The Masdar Institute of Science and Technology (Abu Dhabi) under the joint MI-MIT joint research programme (11WAMA1); Spanish Ministry of Education, COMDIGEST Project (CTM2010-17196). The authors from University of Santiago de Compostela are part of the Galician Competitive Research Group GRC 2013-032, program co-funded by FEDER.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gonzalez-Cabaleiro, Dr Rebeca
• Authors: González-Cabaleiro, R., Lema, J. M., and Rodríguez, J.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• ISSN (Online): 1932-6203
• Copyright Holders: Copyright © 2015 González-Cabaleiro et al.
• First Published: First published in PLoS ONE 10(5): e0126739
• Publisher Policy: Reproduced under a Creative Commons License