International Journal of Biological Sciences

Impact factor

ISSN 1449-2288

News feeds of IJBS published articles
Manuscript login

open access Global reach, higher impact

Journal of Genomics in PubMed Central. Submit manuscript now...


International Journal of Medical Sciences

Journal of Cancer

Journal of Genomics

Journal of Bone and Joint Infection (JBJI)


Journal of Biomedicine


PubMed Central Indexed in Journal Impact Factor

Int J Biol Sci 2013; 9(6):598-612. doi:10.7150/ijbs.6091


Molecular Adaptation Mechanisms Employed by Ethanologenic Bacteria in Response to Lignocellulose-derived Inhibitory Compounds

Omodele Ibraheem, Bongani K. Ndimba

Research and Services Unit, Agricultural Research Council/Infruitech & The University of the Western Cape, Biotechnology Department, Private Bag X17, Bellville, Cape Town, South Africa.


Current international interest in finding alternative sources of energy to the diminishing supplies of fossil fuels has encouraged research efforts in improving biofuel production technologies. In countries which lack sufficient food, the use of sustainable lignocellulosic feedstocks, for the production of bioethanol, is an attractive option. In the pre-treatment of lignocellulosic feedstocks for ethanol production, various chemicals and/or enzymatic processes are employed. These methods generally result in a range of fermentable sugars, which are subjected to microbial fermentation and distillation to produce bioethanol. However, these methods also produce compounds that are inhibitory to the microbial fermentation process. These compounds include products of sugar dehydration and lignin depolymerisation, such as organic acids, derivatised furaldehydes and phenolic acids. These compounds are known to have a severe negative impact on the ethanologenic microorganisms involved in the fermentation process by compromising the integrity of their cell membranes, inhibiting essential enzymes and negatively interact with their DNA/RNA. It is therefore important to understand the molecular mechanisms of these inhibitions, and the mechanisms by which these microorganisms show increased adaptation to such inhibitors. Presented here is a concise overview of the molecular adaptation mechanisms of ethanologenic bacteria in response to lignocellulose-derived inhibitory compounds. These include general stress response and tolerance mechanisms, which are typically those that maintain intracellular pH homeostasis and cell membrane integrity, activation/regulation of global stress responses and inhibitor substrate-specific degradation pathways. We anticipate that understanding these adaptation responses will be essential in the design of 'intelligent' metabolic engineering strategies for the generation of hyper-tolerant fermentation bacteria strains.

Keywords: Fermentation, Bioethanol, Lignocellulosic Inhibitors, Lignocellulolytic materials, Stress Response, Microbial Physiology, Phenolics.

This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY-NC) License. See for full terms and conditions.
How to cite this article:
Ibraheem O, Ndimba BK. Molecular Adaptation Mechanisms Employed by Ethanologenic Bacteria in Response to Lignocellulose-derived Inhibitory Compounds. Int J Biol Sci 2013; 9(6):598-612. doi:10.7150/ijbs.6091. Available from