Page 40 - European Energy Innovation - Spring 2017 publication
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40  Spring 2017 European Energy Innovation


Development of Second
Generation Biorefineries

Production of Dicarboxylic Acids and Bio-based Polymers Derived Thereof (The BioREFINE-2G Project)

THE BIOREFINE-2G PROJECT                                        tools and adaptive evolution, these challenges can be
The project BioREFINE-2G aims at developing commercially        overcome and strains with the desired traits can be obtained.
attractive processes for efficient conversion of pentose-rich
side-streams from biorefineries into dicarboxylic acids, which  PROCESS DEVELOPMENT
can be used as precursors for bio-based polymers including      The challenges in the process development include firstly,
biodegradable polymers.                                         designing the fermentation of a complex raw material, and
                                                                secondly, purifying the desired carboxylic acids from the
STRAIN ENGINEERING                                              fermented broth to a required degree of purity for polymer
Microorganisms are among the most powerful resources on         applications.
earth, but their potential has not yet been fully exploited.
BioREFINE-2G aims at engineering the well-known baker’s         FERMENTATION OF A COMPLEX MEDIUM
yeast to produce industrially relevant dicarboxylic acids. In   BioREFINE-2G works with raw materials containing several
order to develop a sustainable process, the goal is to use      sugars - including a large fraction of pentose sugars – as well
industrial wood waste as substrate.                             as several other compounds, which may affect the physiology
                                                                of the host. The yeast Saccharomyces cerevisiae is a well
Wild-type yeast can neither produce dicarboxylic acids,         suited host to function in these environments.
nor utilize C5 sugars, which are the major fermentable
components of the waste streams. Furthermore, the inhibitors    To enable efficient fermentation, the process conditions are
usually present in the complex biomass hydrolysates can         tuned to reach a suitable compromise between needed
significantly affect cell growth and performance.               fermentation time, product yields and titers. This is done in
                                                                close collaboration with the strain development efforts by the
With the aid of advanced genetic engineering, modelling         molecular biologists.

Strain engineering scheme (DTU)                                                                 DOWNSTREAM PROCESSING
                                                                                                The development of a downstream
                                                                                                processing method for the recovery
                                                                                                of bio-based dicarboxylic acids
                                                                                                faced many challenges to reach
                                                                                                the purity standards suitable for
                                                                                                polymerization. A multi-stage
                                                                                                approach was developed to
                                                                                                overcome the issues posed by
                                                                                                the high amount of lignocellulosic
                                                                                                impurities in the fermentation broth
                                                                                                and by the fermentation by-products.
                                                                                                Recovered solids from complete
                                                                                                process experiments showed that
                                                                                                purity specifications were achieved in
                                                                                                high product yield. The optimization
                                                                                                efforts in recycling and re-use of
                                                                                                streams reduced the economic and
                                                                                                environmental impact of the process.

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