Alcohols enhance the rate of acetic acid diffusion in S. cerevisiae: biophysical mechanisms and implications for acetic acid tolerance
Journal article, 2017

Microbial cell factories with the ability to maintain high
productivity in the presence of weak organic acids, such as acetic acid, are
required in many industrial processes. For example, fermentation media
derived from lignocellulosic biomass are rich in acetic acid and other weak
acids. The rate of diffusional entry of acetic acid is one parameter determining
the ability of microorganisms to tolerance the acid. The present study
demonstrates that the rate of acetic acid diffusion in S. cerevisiae is strongly
affected by the alcohols ethanol and n-butanol. Ethanol of 40 g/L and nbutanol
of 8 g/L both caused a 65% increase in the rate of acetic acid
diffusion, and higher alcohol concentrations caused even greater increases.
Molecular dynamics simulations of membrane dynamics in the presence of
alcohols demonstrated that the partitioning of alcohols to the head group
region of the lipid bilayer causes a considerable increase in the membrane
area, together with reduced membrane thickness and lipid order. These
changes in physiochemical membrane properties lead to an increased number
of water molecules in the membrane interior, providing biophysical
mechanisms for the alcohol-induced increase in acetic acid diffusion rate. nbutanol
affected S. cerevisiae and the cell membrane properties at lower
concentrations than ethanol, due to greater and deeper partitioning in the
membrane. This study demonstrates that the rate of acetic acid diffusion can
be strongly affected by compounds that partition into the cell membrane, and
highlights the need for considering interaction effects between compounds in
the design of microbial processes.

molecular dynamics simulations

inhibitors

n-butanol

membrane permeation

lignocellulose

carbon-14 uptake

ethanol

Author

Lina Lindahl

GMV

Samuel Genheden

Fábio Luis Da Silva Faria Oliveira

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Stefan Allard

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Nuclear Chemistry

Leif A Eriksson

Lisbeth Olsson

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Maurizio Bettiga

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Microbial Cell

2311-2638 (ISSN)

Vol. 5 1 42-55

Subject Categories

Industrial Biotechnology

Biochemistry and Molecular Biology

Environmental Biotechnology

Organic Chemistry

Areas of Advance

Energy

Life Science Engineering (2010-2018)

Roots

Basic sciences

DOI

10.15698/mic2018.01.609

More information

Created

11/22/2018