Presence of proline has a protective effect on weak acid stressed Saccharomyces cerevisiae.
Fermentation of sugars released from lignocellulosic biomass (LCMs) is a sustainable option for the production of bioethanol. LCMs release fermentable hexose sugars and the currently non-fermentable pentose sugars; ethanol yield from lignocellulosic residues is dependent on the efficient conversion of available sugars to ethanol, a side-product of the process is acetic acid production. Presence of acetic acid reduced metabolic output and growth when compared with controls; however, it was observed that incubation with proline had a protective effect, which was proline specific and concentration dependent; the protective effect did not extend to furan or phenolic stressed yeast cells. Proline accumulating strains displayed tolerance to acetic acid when compared with background strains, whereas, strains with a compromised proline metabolism displayed sensitivity. Sensitivity to weak acids appears to be reduced with the addition of proline; proline is an imino acid freely available as a nitrogen source in the aerobic phase of fermentations. Yeast strains with higher intracellular proline concentrations would be desirable for industrial bioethanol fermentations.
School of Biosciences, University of Nottingham, Loughborough, Leicestershire, LE12 5RD, UK, darren.greetham@nottingham.ac.uk.
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D019342:Acetic Acid / Q000633:toxicity*; D050260:Carbohydrate Metabolism; D008031:Lignin / Q000378:metabolism; D011392:Proline / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000502:physiology*; D013312:Stress, Physiological
C036909:lignocellulose; D008031:Lignin; D011392:Proline; D019342:Acetic Acid