The research shows that the combination of marine microbes that can grow on plastic waste varies significantly from microbial groups that colonize surfaces in the wider environment. This raises the possibility that the plastic-associated marine microbes have different activities that could contribute to the breakdown of these plastics or the toxic chemicals associated with them.
While microbes are the most numerous organisms in the marine environment, this is the first DNA-based study to investigate how they interact with plastic fragments. The scientists found that the plastic polyethylene – commonly used for shopping bags - was rapidly colonized by multiple species of bacteria that congregated together to form a 'biofilm' on its surface. Interestingly, the biofilm was only formed by certain types of marine bacteria.
Plastic waste is a long-term problem as its breakdown in the environment may require thousands of years. "Plastics form a daily part of our lives and are treated as disposable by consumers. As such plastics comprise the most abundant and rapidly growing component of man-made litter entering the oceans," explained co-author Jesse Harrison.
Over time the size of plastic fragments in the oceans decreases as a result of exposure to natural forces. Tiny fragments of 5 mm or less are called "microplastics" and are particularly dangerous as they can absorb toxic chemicals which are transported to marine animals when ingested.
The research team plans to investigate how the microbial interaction with microplastics varies across different habitats within the coastal seabed – research which they believe could have huge environmental benefits.
"Microbes play a key role in the sustaining of all marine life and are the most likely of all organisms to break down toxic chemicals, or even the plastics themselves," suggested Harrison. "This kind of research is also helping us unravel the global environmental impacts of plastic pollution," he said.