Innovative Solutions for Environmental Challenges: Plastic-Eating Bacteria

Far beneath the ocean's surface, researchers have discovered bacteria capable of digesting plastic, particularly polyethylene terephthalate, or PET, which is commonly found in drink bottles and fabrics.

A large-scale global study conducted by scientists at King Abdullah University of Science and Technology has revealed that these marine microbes are widespread and possess specialized enzymes that have evolved alongside humanity's synthetic debris.

Carlos Duarte, a marine ecologist and co-leader of the study, explains that a distinctive structural feature on a plastic-degrading enzyme called PETase, known as the M5 motif, acts as a molecular signature indicating the enzyme's ability to break down PET.

This finding significantly shifts previous beliefs that PET was nearly impossible to degrade naturally, a notion that began to change in 2016 with the discovery of a bacterium in a Japanese recycling plant capable of consuming plastic waste.

However, it remained uncertain whether oceanic microbes had similarly developed these enzymes independently. Through a combination of artificial intelligence modeling, genetic screening, and laboratory testing, Duarte and his team confirmed that the M5 motif distinguishes effective PET-degrading enzymes from inactive variants.

In tests, marine bacteria containing the complete M5 motif were shown to efficiently break down PET samples, with genetic activity maps indicating that M5-PETase genes are highly active in the oceans, particularly in areas heavily polluted with plastic.

The researchers examined over 400 ocean samples globally, finding that functional PETases with the M5 motif appeared in nearly 80 percent of tested waters, from surface gyres filled with floating debris to nutrient-poor depths nearly two kilometers below.

This ability to utilize synthetic carbon may provide these microbes with a crucial survival advantage, as noted by senior bioinformatics researcher Intikhab Alam. However, Duarte cautions that while this discovery highlights nature's remarkable adaptability, it does not offer a quick fix to the plastic pollution crisis, as the microbial breakdown process is far too slow to counteract the massive influx of plastic waste entering oceans each year.

On land, these findings could help accelerate advancements in sustainable recycling methods. The diverse range of PET-degrading enzymes that evolved in the deep sea may serve as models for optimization in laboratory settings, potentially leading to more efficient degradation processes in treatment facilities and homes.

The identification of the M5 motif provides a roadmap for engineering faster, more effective enzymes, revealing structural traits that function under real environmental conditions. If scientists succeed in replicating and enhancing these natural mechanisms, humanity may gain powerful allies in the ongoing battle against plastic pollution, originating from one of the planet's most unexpected locations: the deep ocean.