Plastic’s moldability, versatility and durability have made it indispensable in
modern industry; yet, since conventional plastic is produced from crude oil — a
non-renewable resource — and persists in the environment, it has also emerged as
one of our most significant sources of global
pollution.
Engineers, researchers and startups around the world continue to search for
alternatives; but the hunt continues for any that exhibit all of the same
advantages as conventional plastics while avoiding their problems.
One of the most promising alternatives is polylactic
acid (aka
polylactide or PLA) — a compostable bioplastic often produced from
plants; but it tends to be brittle and does not degrade well.
To address this, bioengineers from Japan’s Kobe
University, led by professor Seiichi Taguchi
— together with biodegradable polymer producer Kaneka
Corporation and the National Institute of
Advanced Industrial Science and
Technology — tested a mix
of polylactic acid with another bioplastic, called
LAHB, which is
biodegradable and mixes well with polylactic acid. However, to produce LAHB, the
researchers needed to engineer a strain of bacteria that naturally produces a
precursor — by manipulating the organism’s genome through the addition of new
genes and the deletion of interfering ones.
In the journal, ACS Sustainable Chemistry &
Engineering, the
bioengineering teams report that they successfully created a ‘bacterial plastic
factory’ that produces chains of LAHB in high amounts — using glucose as
feedstock. In addition, they report that by modifying the genome, they could
control the length of the LAHB chain and thus the properties of the resulting
plastic — thus producing LAHB chains up to ten times longer than with
conventional methods, which they call “ultra-high molecular weight LAHB.”
What’s notable about this is that, by adding LAHB of this unprecedented length
to polylactic acid, the researchers were able to create a material that exhibits
all of the properties they had hoped for — the resulting, highly transparent
plastic is much more moldable and more shock resistant than pure PLA and
biodegrades in seawater within a week.
“By blending polylactic acid with LAHB, the multiple problems of polylactic acid
can be overcome in one fell swoop,” Taguchi
explains, “and the
so-modified material is expected to become an environmentally sustainable
bioplastic that satisfies the conflicting needs of physical robustness and
biodegradability.”
But the Kobe University bioengineers say the benefits don’t end there: The
strain of bacteria they used in this work is, in principle, able to use CO2 as a
raw material, making it possible to synthesize useful plastics directly from the
greenhouse gas — a process that companies such as LanzaTech are scaling
through various corporate
partnerships.
Ultimately, Taguchi says, “Through the synergy of multiple projects, we aim to
realize a biomanufacturing technology that effectively links microbial
production and material development” — so, stay tuned.
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Sustainable Brands Staff
Published Apr 11, 2024 8am EDT / 5am PDT / 1pm BST / 2pm CEST