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  • Voltaire Staff

Bacteria that can eat plastic, help it decompose

Plastic waste's persistent environmental impact may soon face a formidable opponent as researchers have claimed to unveil plastic-eating bacteria.

Traditionally impervious to decomposition due to their chemical stability, polymers, which plastic is composed of, have posed a challenge for natural degradation processes.

However, an international research team has claimed to incorporate some specialised bacteria directly into plastic materials which may decompose them.

By introducing the bacteria as inactive spores, their plastic-consuming activity remains dormant until disposal into the environment. The approach not only tackles plastic waste but also strengthens the material, researchers claimed.

"The incorporation of bacterial spores presents exciting opportunities for the introduction of living cells as renewable polymer fillers in industrial processes. This innovative approach combines evolutionary and genetic engineering methodologies and shows potential for diverse applications in the advancement of biocomposite materials," the study, published in the journal Nature Communications, said.

Although polymers chemical breakdown is possible, it's energy-intensive and yields few useful byproducts.

Bacteria offer a promising solution, using enzymes to break down polymers into energy sources. Though scarcity of suitable enzymes has hindered progress, exposure to plastics over decades has spurred the emergence of plastic-consuming bacterial strains.

Researchers embedded these bacteria within the plastic itself. The plastic in focus, thermoplastic polyurethane (TPU), is omnipresent, found in items like bicycle inner tubes and Ethernet cable coatings.

According to researchers, certain bacteria, such as Bacillus subtilis, possess the ability to break down TPU. B. subtilis, a harmless soil bacterium found in our digestive tracts, produces spores, enabling survival in unfavourable conditions.

The method allows B. subtilis spores remain dormant while TPU is in use, only activating to digest it upon disposal.

The mechanism also ensures bacteria activation occurs only in suitable environmental conditions, such as those found in landfills or soil, minimizing risks in everyday use scenarios.

The challenge initially faced by researchers was the high temperatures used in TPU manufacturing, typically lethal to bacteria. At 130°C, over 90 per cent of B. subtilis spores were killed in just one minute. To overcome this, they subjected the spores to lower temperatures and brief heat exposure, eliminating most bacteria.

Surviving strains were then cultivated, induced to sporulate, and subjected to increasingly harsh conditions, leading to the evolution of a strain tolerant to high temperatures for up to 30 minutes. This evolved strain was integrated into TPU via standard extrusion processes.

To mimic landfill or litter conditions, researchers placed plastic samples in compost. Even without added bacteria, organisms degraded plain TPU by nearly 50 per cent in five months. However, with B. subtilis spores, the plastic lost 93 per cent of its mass in the same period.

While the method shows promise, not all plastics degrade easily, and certain uses may activate spores unintentionally, posing challenges.






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