Unlocking the Secrets of Plastic-Eating Bacteria: A Groundbreaking Discovery

Researchers have long been puzzled by the ability of a common family of environmental bacteria, Comamonadacae, to thrive on plastics found in urban rivers and wastewater systems. Now, a team of scientists from Northwestern University has unraveled the mystery, revealing how these bacteria break down plastic and use it as a food source.

Transforming Waste into Sustenance: The Remarkable Abilities of Comamonas Bacteria

Chewing, Secreting, and Consuming: The Multistep Process of Plastic Degradation

The researchers have discovered a remarkable process by which Comamonas bacteria break down plastic materials. First, the bacteria chew the plastic into small, nanoscale pieces. Then, they secrete a specialized enzyme that further breaks down the plastic. Finally, the bacteria use the carbon atoms from the plastic as a food source, fueling their growth and survival."We have systematically shown, for the first time, that a wastewater bacterium can take a starting plastic material, deteriorate it, fragment it, break it down and use it as a source of carbon," said Ludmilla Aristilde, the lead researcher and an associate professor of environmental engineering at the McCormick School of Engineering. "It is amazing that this bacterium can perform that entire process, and we identified a key enzyme responsible for breaking down the plastic materials."

Tackling the Plastic Pollution Crisis: Harnessing Bacteria for Environmental Solutions

The discovery of Comamonas bacteria's ability to degrade plastic opens up new possibilities for developing bacteria-based engineering solutions to address the growing problem of plastic waste. Plastic pollution has become a major environmental concern, contaminating drinking water and harming wildlife.The researchers focused their attention on polyethylene terephthalate (PET), a type of plastic commonly used in food packaging and beverage bottles. PET is a significant contributor to plastic pollution, as it does not break down easily. In fact, PET plastics represent 12% of total global plastics usage and account for up to 50% of microplastics found in wastewater.

Unraveling the Mechanisms: Observing Plastic Degradation in Action

To better understand how Comamonas testosteroni interacts with and feeds on plastic, the researchers employed a multifaceted approach. They first grew the bacteria on PET films and pellets, observing how the surface of the plastic material changed over time. Next, they examined the water around the bacteria, searching for evidence of plastic broken down into smaller, nano-sized pieces.The researchers then delved deeper, looking inside the bacteria to identify the tools they use to degrade the PET. Through advanced omics techniques, they discovered a specific enzyme that the bacterium expressed when exposed to PET plastics. To further explore the enzyme's role, the researchers collaborated with scientists at Oak Ridge National Laboratory, who prepared bacterial cells without the ability to express this key enzyme. Remarkably, without this enzyme, the bacteria's ability to degrade plastic was significantly diminished or lost altogether.

Implications for Understanding Plastic Behavior in Wastewater

The researchers' findings not only have implications for potential environmental solutions but also shed light on the behavior of plastics in wastewater. Aristilde explains that wastewater is a significant reservoir of microplastics and nanoplastics, and most people assume that these small particles enter wastewater treatment plants as they are.However, the researchers' work suggests that nanoplastics can actually be formed during the wastewater treatment process through microbial activity. This is an important consideration as society tries to understand the journey of plastics from wastewater to receiving rivers and lakes."Wastewater is a huge reservoir of microplastics and nanoplastics," Aristilde said. "We're showing that nanoplastics can be formed during wastewater treatment through microbial activity. That's something we need to pay attention to as our society tries to understand the behavior of plastics throughout its journey from wastewater to receiving rivers and lakes."The groundbreaking research, published in the journal Environmental Science & Technology, has the potential to revolutionize our approach to tackling the plastic pollution crisis. By harnessing the remarkable abilities of Comamonas bacteria, scientists may be able to develop innovative solutions to clean up and manage the growing problem of plastic waste.