Plants can make
a broad range of
biodegradable
materials with
light as the
energy input and
atmospheric
carbon dioxide
as the source of
the carbon
backbones of
these
biomaterials,
substituting
fossil carbon.
This makes them
specially
valuable in the
perspective of
sustainable
development and
of the new « Bioeconomy »,
defined by OECD
as « the
aggregate set of
economic
operations in a
society that use
the latent value
incumbent in
biological
products and
processes to
capture new
growth and
welfare benefits
for citizens and
nations » (www.oecd.org).
As first
examples, plants
have been
genetically
engineered to
produce
plastics, more
precisely
polyhydroxybutyrate,
a
biodegradable
polyester
naturally
produced by a
bacterium named
Alcaligenes
eutrophus,
and ressembling
polypropylene.
Although the
operation was
successful in
model and crop
plants (including
mustard, cotton
and maize), the
economic
feasibility of
the approach has
still to be
worked out.
Another approach
for producing
biomaterials
from renewable
plant
resources is to
use plant sugars
as starting
material.
Starch is
one of them,
from which
biodegradable
plastics can be
produced in an
increasingly
cost-effective
way. Genetic
engineering
can help tailor
the structure of
starch to modify
its
physicochemical
properties and
facilitate its
industrial
processing.
Cellulose is
the most
abundant plant
sugar on the
planet, from
which many
derivatives are
being used by
the chemical
industry. In
this case, the
genetic
engineering of
poplar trees is
being used to
make pulp
extraction less
polluting, by
modifying the
chemical
composition of
lignin, a lipid
polymer which is
tightly bound to
cellulose and
needs to be
removed by toxic
chemicals during
pulp processing.
Starting from
plant sugars,
fermentation
technologies can
create a real
blossom of
molecules and
polymers valued
by the industry.
Green and white
biotechnologies
then work
together to meet
the challenges
of the new
Bioeconomy.
