Creating “living plastic” that can contain bacteria and decompose

Plastics take decades or even centuries to break down, and this type of waste contributes to the pollution of land and oceans.

That’s why scientists around the world are constantly working to develop technologies to break down plastic in the most efficient way.

With this in mind, a team of scientists led by the University of California, San Diego, developed a biodegradable plastic filled with bacterial spores and thermoplastic polyurethane pellets.

A team led by the Jacobs School of Engineering and the University of San Diego Materials Science and Engineering Research Center (MRSEC) has successfully designed a “living plastic” that can be composted.

Research shows that this “living plastic” is a biodegradable form of thermoplastic polyurethane (TPU), a type of durable commercial plastic used to make shoes, mats (carpets), pillows, and foam. It is.

This biodegradable material was produced by loading bacterial spores of a Bacillus subtilis strain that has the ability to degrade plastic polymeric materials.

These bacteria are widely distributed in the soil, and at the end of their lives they germinate and decompose when they come into contact with nutrients contained in fertilizers.

“This is a unique property of these bacteria,” said John Pokorski, professor of nanoengineering and co-lead author of the study published in Nature Communications. “We took several strains, evaluated their ability to use TPU as the sole carbon source, and selected the strains that would grow better.”

The researchers used an inactive form of the bacteria, which has a protective shield and is therefore resistant to harsh environmental conditions. They designed it to be very resistant to temperature.

To create the new biodegradable plastic, the scientists introduced the spores and thermoplastic polyurethane granules into a press, where both components were mixed and melted at a temperature of 135 degrees Celsius. Then I made the plastic strips as usual.

We then evaluated the biodegradability of the resulting material and found that the moisture and other nutrients contained in the compost caused the germination of spores inside the plastic, and when placed inside the compost under ideal conditions at 37°C, 5 After several months, it was found that 90% of the material had biodegraded. ℃ including humidity. Ranges from 44 to 55%.

Scientists also discovered another benefit of this material. That’s because plastic made from Bacillus subtilis is 37% stronger and 30% less likely to break than traditional thermoplastic polyurethane.

In this way, the bacterial spores on the material act as “fillers” for reinforcement.

The detailed study was published in the journal Nature Communications.

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