Israeli researchers in conjunction with a Portuguese recycling company are working to develop a novel way of recycling plastic from bacteria

Recycling plastics with bacteria could be a simpler way to process and reuse discarded plastics. Members of the Ben-Gurion University of the Negev are investigating biodegradation by bacteria, a simpler and more ecological way to decompose and recycle PET (Polyethylene Terephthalate), one of the most common types of plastic in food and beverage packaging, as well as in textile products.

Last November, a research collaboration agreement was signed between BGN Technologies, the Ben-Gurion University technology company, and the Portuguese company Ecoibéria as part of a year-long project to study and demonstrate the efficacy of PET’s bacterial biodegradation.

The results of the joint study could provide a simpler alternative to the cumbersome plastic recycling process used today, which involves collecting plastic bottles from recycling bins before sorting them out by type and color and then shredding them into small chips and melt them into sheets of raw material and fibers.

A 20-year investigation

“Our research dealt with the breakdown of various plastics polymers,” explains Professor Ariel Kushmaro from the department of biotechnological engineering at BGU.

The principal investigator for this project was Professor Alex Sivan, who began working in this field 20 years ago, when global research on the biological breakdown of plastics was in its infancy.

“We start from the understanding that biodegradation derives from the microorganism’s requirement for a source of energy and carbon. For that, they break down organic matter – carbon chains, like sugars and even proteins. We thought that because plastic, polyethylene and PET were also made of carbon chains, we would prepare a kind of ‘enrichment culture’: soil that became contaminated over the years with plastic or PET with its original bacterial population. ”, Says Kushmaro.

The Polyethylene Challenge

One of the biggest challenges that research has encountered is that Polyethylene is considered a non-biodegradable substance due to its highly stable carbon-carbon bonds. This is why its bacterial decomposition must be facilitated manually in a laboratory.

“Together with the bacteria, we added the material that we wanted them to decompose and we let them act for a few weeks. After several attempts, we saw a microorganism that grows and uses Polyethylene as a source of carbon and energy. These are the bacteria that polymers can handle, ”Kushmaro explained.

We found that for bacteria to biodegrade the carbon bonds in plastic polymers, they had to be grown in a carbon-free environment, so that the bacteria had no choice but to consume the only carbon available in the plastic to survive. “

Kushmaro, Sivan, and their research team ended up discovering several types of bacteria capable of successfully biodegrading Polyethylene microplastics in soil samples.

“We showed that in 30 days, 10 to 20 percent of the weight of the soil was lost simply due to the decomposition activity carried out by the bacteria, which emitted carbon dioxide in the process of respiration,” concluded Kushmaro.