Materials & Packaging

Researchers Tweak Bacteria to Create Strong, Flexible, Sustainable Plastic

Researchers at Kobe University have engineered bacteria to produce a plastic modifier that makes bioplastic more processable, more fracture resistant and highly biodegradable —which holds great potential for enabling sustainable plastic production.

Published 7 months ago | About a 3 minute read

Image: Industrial manufacturing requires a high degree of melt tension, which can be demonstrated by how little a material sags when heated. LAHB-added PLA (left) sags much less than pure PLA (right), proving that it is a better processable material. | Koh Sangho

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.