title: Chaotropicity: a key factor in product tolerance of biofuel-producing microorganisms.
abstract: Fermentation products can chaotropically disorder macromolecular systems and induce oxidative stress, thus inhibiting biofuel production. Recently, the chaotropic activities of ethanol, butanol and vanillin have been quantified (5.93, 37.4, 174kJ kg(-1)m(-1) respectively). Use of low temperatures and/or stabilizing (kosmotropic) substances, and other approaches, can reduce, neutralize or circumvent product-chaotropicity. However, there may be limits to the alcohol concentrations that cells can tolerate; e.g. for ethanol tolerance in the most robust Saccharomyces cerevisiae strains, these are close to both the solubility limit (<25%, w/v ethanol) and the water-activity limit of the most xerotolerant strains (0.880). Nevertheless, knowledge-based strategies to mitigate or neutralize chaotropicity could lead to major improvements in rates of product formation and yields, and also therefore in the economics of biofuel production.
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Cray
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Stevenson
authors.affiliation: 18 Hillcourt Road, East Dulwich, London SE22 0PE, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Ball
authors.affiliation: Department of Chemical Engineering, College of Engineering, Bharati Vidyapeeth University, Pune-Satara Road, Pune 411043, India.
authors.forename: Sandip B
authors.initials: SB
authors.lastname: Bankar
authors.affiliation: Universidade Federal do Rio de Janeiro, Instituto de Quimica, Programa de Pós-graduação Bioquimica, Rio de Janeiro, RJ, Brazil.
authors.forename: Elis C A
authors.initials: EC
authors.lastname: Eleutherio
authors.affiliation: Department of Animal Sciences and Ohio Agricultural Research and Development Center (OARDC), The Ohio State University, 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Thaddeus C
authors.initials: TC
authors.lastname: Ezeji
authors.affiliation: Department of Food Engineering and Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai, Maharashtra 400019, India.
authors.forename: Rekha S
authors.initials: RS
authors.lastname: Singhal
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven and Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, Flanders, Leuven-Heverlee B-3001, Belgium.
authors.forename: Johan M
authors.initials: JM
authors.lastname: Thevelein
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Timson
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK. Electronic address: j.hallsworth@qub.ac.uk.
authors.forename: John E
authors.initials: JE
authors.lastname: Hallsworth
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000096:biosynthesis; D056804:Biofuels; D000440:Butanols / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D006801:Humans; D012441:Saccharomyces cerevisiae / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D056804:Biofuels; D000440:Butanols; D000431:Ethanol