Plastic-eating bacteria discovered in the ocean

Far beneath the ocean’s surface, researchers have found bacteria that can digest plastic, using specialized enzymes that evolved alongside humanity’s synthetic debris. A large-scale global study by scientists at KAUST (King Abdullah University of Science and Technology) revealed that these marine microbes are widespread and genetically prepared to consume polyethylene terephthalate (PET) — the tough plastic used in everyday items like drink bottles and fabrics.

Their remarkable ability stems from a distinct structural feature on a plastic-degrading enzyme called PETase. This feature, known as the M5 motif, acts as a molecular signature that signals when an enzyme can truly break down PET. For decades, scientists believed PET was almost impossible to degrade naturally. That belief began to shift in 2016, when a bacterium discovered in a Japanese recycling plant was found to survive by consuming plastic waste. It had developed a PETase enzyme capable of dismantling plastic polymers into their building blocks. Yet it remained unclear whether oceanic microbes had developed similar enzymes independently.

To understand how widespread these enzymes are, the researchers examined more than 400 ocean samples collected from across the globe. Functional PETases containing the M5 motif appeared in nearly 80 percent of the tested waters, ranging from surface gyres filled with floating debris to nutrient-poor depths nearly two kilometers below. In the deep sea, this ability may give microbes an important edge. The ability to snack on synthetic carbon may confer a crucial survival advantage, noted Intikhab Alam, a senior bioinformatics researcher and co-leader of the study. The discovery highlights a growing evolutionary response: microorganisms are adapting to human pollution on a planetary scale.

Source: Science Daily