Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae

Journal Article · Fri Aug 26 00:00:00 EDT 2016 · AMB Express

DOI:https://doi.org/10.1186/s13568-016-0234-8· OSTI ID:1325063

Narayanan, Venkatachalam ^[1]; Sànchez i Nogué, Violeta ^[2]; van Niel, Ed W. J. ^[1]; Gorwa-Grauslund, Marie F. ^[1]

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1. Lund Univ., Lund (Sweden)
2. National Renewable Energy Lab. (NREL), Golden, CO (United States)

Here, lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotype involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 +/- 5 h to yield 0.45 +/- 0.01 g ethanol g glucose^-1) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: Swedish National Energy Agency; USDOE
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1325063
• Report Number(s): NREL/JA-5100-67105
• Journal Information: AMB Express, Vol. 6, Issue 1; ISSN 2191-0855
• Publisher: Springer
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
Saccharomyces cerevisiae
low pH
lignocellulosic inhibitors
phenotypic robustness
adaptation
ethanol yield