Open AccessBatch and continuous culture‐based selection strategies for acetic acid tolerance in xylose‐fermenting Saccharomyces cerevisiae
Author(s) -
Wright Jeremiah,
Bellissimi Eleonora,
de Hulster Erik,
Wagner Andreas,
Pronk Jack T.,
van Maris Antonius J. A.
Publication year - 2011
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/j.1567-1364.2011.00719.x
Subject(s) - acetic acid , xylose , fermentation , chemostat , biology , biochemistry , food science , bioreactor , saccharomyces cerevisiae , ethanol , yeast , botany , bacteria , genetics
Acetic acid tolerance of Saccharomyces cerevisiae is crucial for the production of bioethanol and other bulk chemicals from lignocellulosic plant‐biomass hydrolysates, especially at a low pH. This study explores two evolutionary engineering strategies for the improvement of acetic acid tolerance of the xylose‐fermenting S. cerevisiae RWB218, whose anaerobic growth on xylose at pH 4 is inhibited at acetic acid concentrations >1 g L −1 : (1) sequential anaerobic, batch cultivation (pH 4) at increasing acetic acid concentrations and (2) prolonged anaerobic continuous cultivation without pH control, in which acidification by ammonium assimilation generates selective pressure for acetic acid tolerance. After c . 400 generations, the sequential‐batch and continuous selection cultures grew on xylose at pH≤4 with 6 and 5 g L −1 acetic acid, respectively. In the continuous cultures, the specific xylose‐consumption rate had increased by 75% to 1.7 g xylose g −1 biomass h −1 . After storage of samples from both selection experiments at −80 °C and cultivation without acetic acid, they failed to grow on xylose at pH 4 in the presence of 5 g L −1 acetic acid. Characterization in chemostat cultures with linear acetic acid gradients demonstrated an acetate‐inducible acetic acid tolerance in samples from the continuous selection protocol.