Bacteria-Killing Plastic Toxins Threatens 20% of World's Oxygen

Scientists have revealed that a potential new problem associated with the plastic pollution epidemic is the inhibition of growth and photosynthetic efficiency of the bacteria that produces about 20% of the world's breathable oxygen supply, due to toxins in plastic seeping into seawater. 

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The bacteria, Prochlorococcus, also captures approximately the same percentage of carbon on the planet. When one carbon molecule goes in, an oxygen molecule is released. Prochlorococcus produces its own food through photosynthesis, which is the process of gathering carbon and excreting oxygen. Not only does the bacteria take in carbon, but it also takes in the toxins from plastics, also known as leachates.

In an experiment to analyze the effect of the bacteria, researchers constructed several artificial seawater bases and added varying amounts of plastic, as well as the bacteria, to each one. A control of Prochlorococcus growing in artificial seawater with no plastic was used for comparative purposes. As the concentration of leachate increased, the bacteria's physiological response began to show troubling variations. 

According to Lisa Moore, a microbial oceanographer with the Macquarie University in Australia and co-author of the study, “when the plastic leachates increase in concentration, you see that the cells don't grow as well, and in fact, at the highest concentrations they are dying.”

Not only was the bacteria cells' growth stunted by the increased presence of leachates, but the researchers also witnessed “a decrease in photosynthetic efficiency, and in fact, a pretty dramatic decrease with the higher concentrations.”

There are several elements of plastic that could cause inhibited growth and photosynthetic efficiency, such as flame retardants, additives and zinc.

Out of all the photosynthesizing organisms in the world, Prochlorococcus is the most abundant. 

While the study of how plastic pollution affects this particular molecule is still in the early stages, it also gives researchers a sense of the challenges that come with studying the relatively new concept of plastic pollution.