Background: A future bioeconomy relies on the efficient use of renewable
resources for energy and material product supply. In this context,
biorefineries have been developed and play a key role in converting
lignocellulosic residues. Although a holistic use of the biomass feed is
desired, side streams evoke in current biorefinery approaches. To ensure
profitability, efficiency, and sustainability of the overall conversion
process, a meaningful valorization of these materials is needed. Here, a
so far unexploited side stream derived from fast pyrolysis of wheat
straw-pyrolysis water-was used for production of 1,2-propanediol in
microbial fermentation with engineered Corynebacterium glutamicum.
Results: A protocol for pretreatment of pyrolysis water was established
and enabled growth on its major constituents, acetate and acetol, with
rates up to 0.36 +/- 0.04 h(-1). To convert acetol to 1,2-propanediol,
the plasmid pJULgldA expressing the glycerol dehydrogenase from
Escherichia coli was introduced into C. glutamicum. 1,2-propanediol was
formed in a growth-coupled biotransformation and production was further
increased by construction of C. glutamicum.pqo.aceE.ldhA.mdh pJULgldA.
In a two-phase aerobic/microaerobic fed-batch process with pyrolysis
water as substrate, this strain produced 18.3 +/- 1.2 mM 1,2-propanediol
with a yield of 0.96 +/- 0.05 mol 1,2-propanediol per mol acetol and
showed an overall volumetric productivity of 1.4 +/- 0.1 mmol
1,2-propanediol -L-1 h(-1).
Conclusions: This study implements microbial fermentation into a
biorefinery based on pyrolytic liquefaction of lignocellulosic biomass
and accesses a novel value chain by valorizing the side stream pyrolysis
water for 1,2-PDO production with engineered C. glutamicum. The
established bioprocess operated at maximal product yield and
accomplished the so far highest overall volumetric productivity for
microbial 1,2-PDO production with an engineered producer strain.
Besides, the results highlight the potential of microbial conversion of
this biorefinery side stream to other valuable products.
Please log in
to take part in the discussion (add own reviews or comments).