Welcome to the 'plastisphere': the synthetic ecosystem evolving at sea

[1] Plastic bottles dominate waste in the ocean, with an estimated 1m of them reaching the sea every minute. The biggest culprit is polyethylene terephthalate (Pet) bottles.

[2] Last month, a study found two bacteria capable of breaking down Pet - or, as the headlines put it, “eating plastic”. Known as Thioclava sp. BHET1 and Bacillus sp. BHET2, the bacteria were isolated in a laboratory - but they were discovered in the ocean.

[3] The bacteria are the latest example of new organisms that appear, to be growing in a unique environment: the vast amounts of plastic at sea.

[4] Like the atmosphere, magnetosphere and hydrosphere, the plastisphere is a region. But it is also an ecosystem, like the Siberian steppe or coral reefs - a plasticised marine environment. The best-known concentration of seaborne plastic waste is the Great Pacific garbage patch, a sort of plastic soup spread over an area roughly twice the size of France, but plastic is everywhere.

[5] First described in a 2013 study to refer to a collective of plastic-colonising organisms, including bacteria and fungi, the term has since expanded. It now loosely encompasses larger organisms, from crabs to jellyfish, which float across oceans on marine plastics. The term was coined by Linda Amaral-Zettler, a marine microbiologist at the Royal Netherlands Institute for Sea Research.

[6] Although the term may be recent, the phenomenon is not. “The plastisphere has been around for as long as plastic has existed,” Amaral-Zettler says.

[7] What is new is our understanding of just how complex an ecosystem the world of plastic can be. In the plastisphere there are organisms that photosynthesise;

there are predators and prey; symbionts and parasites, allowing for “a full range of interactions possible, as in other ecosystems”, says Amaral-Zettler.

[8] Another unique feature of the plastisphere is that humans invented it. Every other ecosystem has evolved over millions of years. The meaning of that is not yet clear. Wright believes “its more an issue of scale” because unlike most naturally occurring materials, plastic is highly durable and persistent, allowing the growth and spread of attached organisms over a massive area.

[9] There are also concerns about plastic-colonising organisms that can travel around the world. AmaralZettler's 2013 study discovered Vibrio, a type of bacteria

known to contain several species of pathogens, including some associated with gastroenteritis.

 

[10] For the scientists, the plastisphere's presence is a less obvious concern than its potential health dangers. Most plastic ends up in landfill, but nearly a third of it ends up in the sea. The majority sinks, but a lot does not, becoming a home for all sorts of microbes that might not otherwise have a home.

[11] “At the moment that's still very much an active area of research,” Wright says. There are two main fields of investigation: potential pathogens in the plastisphere, and the potential for some microbes to biodegrade hydrocarbons, such as the plastic-eaters identified last month.

[12] Those are not unique to the ocean. In 2016, scientists in Japan discovered Ideonelta sakaiensis, a species of bacteria at a rubbish tip that had evolved an enzyme that enabled it to eat plastic.

 

[13] But another study in the same year found that, compared with bacteria in the surrounding waters, those in the plastisphere possessed an enriched collection of genes, suggesting that they had adapted for a “surface-attached lifestyle”.

[14] Could the plastisphere evolve in such a way that bacteria would essentially eat it, or at least help us identify ways to break down our plastic waste? “I'd definitely agree that [microbes on] plastics are going to be the key place to look in the fight against plastic,” says Wright.

(Adapted from: htips://www .theguardian.com) 

Decide if the statements below are true (T) or false (F) according to the text. Then, choose the option that contains the right sequence.

(   ) The plastisphere is one more ecosystem in our world and it is similar to all other ecosystems that exist.

(   ) The atmosphere, the magnetosphere and the hydrosphere gave origin to the plastisphere.

(   ) In addition to bacteria and fungi, some animals can travel to many countries on marine plastics.

(   ) The bacteria in the plastisphere can be characterized as a group of bacteria that have not become adapted to living on the surface.

(   ) Wright believes that we can combat plastic pollution if we do research on microbes that eat or decompose plastic waste.