VOA标准英语2013--Bacteria Thrive on Ocean Plastic Debris

（单词翻译）

Bacteria Thrive on Ocean Plastic Debris¹

It takes about six weeks for a plastic bag or bottle to ride the surface currents from the U.S. East Coast to the Sargasso Sea, in the center of the North Atlantic. The area is a gyre, essentially² a big whirlpool that traps and swirls³ the debris which, unlike other types of trash in the ocean, never bio-degrades.

This is where Tracy Mincer⁴, a microbiologist with Woods Hole Oceanographic Institution, and colleagues from the Marine⁵ Biological Laboratory, joined students aboard a Sea Education Association vessel⁶ to sample plastic debris for microbes.  

“We hypothesized that the microbes on plastic were specifically interacting with it, rather than just a random⁷ association," Mincer said. "It’s not just flypaper that is just grabbing on to anything. Things are actually specifically interacting with plastic for a reason.”

The team skimmed the surface with fine nets, collecting confetti size bits of plastic. They analyzed⁸ the plastic with electron scanning tools and gene⁹ sequencing techniques. They found rich colonies of bacteria, including some that they hadn’t expected, which they called 'pit formers.'

“We were surprised when we saw microbes that appeared to be hydrolyzing [breaking down] the plastic and etching into it," said Mincer, "as well as just a whole other amazing ecosystem¹⁰ that was thriving on this plastic surface.”

The organisms in this plastisphere were different from those in the surrounding nutrient-poor water, indicating that the plastic acts as an artificial microbial reef, one that could harbor disease-causing pathogens and other harmful algal species.   

“It’s certainly possible. And a lot of time certain toxins¹¹ are oily in nature and they will absorb on to the plastic, but when the microbes interact with it they could be releasing those toxins off of the plastics,” Mincer said.

Hormonal¹² effects

Some of those additives¹³ are known to have hormonal effects in humans.  

More than 90 percent of the trash floating on the ocean surface is plastic. The largest of the planet's five gyre sites is the Great Pacific Garbage Patch, which is twice the size of Texas. Mincer says with so much plastic out there, it is important to know how it impacts marine species and by extension, people.  

“Fish are eating the plastic," Mincer said. "Are they picking up certain toxins from the plastic or not? And what does happen to plastic once it goes out into this environment? Does it eventually degrade into little tiny bits? And then what does it do?  Do the microbes make it heavier and make it sink quicker? Does it go away?  Is it a problem?”

The initial survey identified about 1,000 microbes that live on and interact with plastic. The next step is to sequence their genomes to get a better idea of whether or not they could be harmful pathogens.