Ocean microbes may be developing taste for plastic pollution

We’ve poured more than 150 million metric tons of plastic garbage into the ocean since 1950. Plastic bits have turned up in places as remote as the bottom of the Mariana Trench, where scientists recently found an intact plastic bag some 6 kilometers below the ocean surface.

So it should come as no surprise that life in the deep has figured out how to extract carbon – a building block of life from even this seemingly indestructible material. Scientists have discovered ocean bacteria with genes suggesting they are equipped to break down and eat plastic. “In the ocean, where carbon is scarce, microbes seem to have fine-tuned these enzymes to make use of this new, human-made carbon source: plastic,” said Carlos Duarte, a marine ecologist at King Abdullah University of Science and Technology in Saudi Arabia.

This isn’t the first time plastic-eating microbes have been discovered. In 2016, Japanese scientists first reported they had found bacteria in effluent from a plastic recycling plant capable of breaking down polyethylene terephthalate (PET), a plastic polymer used to make, among other things, those ubiquitous clear beverage bottles.

The discovery sparked a global hunt for other microbes capable of chomping on plastic with a special type of enzyme called a PETase (all enzymes have the “ase” suffix). Scientists were spurred partly by curiosity to see how far the plasticization of the planet had left its fingerprints on genetics, and partly by the hope that such critters could be harnessed to improve plastic recycling.

Scientists have since genetically engineered microorganisms capable of such feats, including ocean-going microbes. .IRPP_ruby , .IRPP_ruby .postImageUrl , .IRPP_ruby .centered-text-area {height: auto;position: relative;}.IRPP_ruby , .IRPP_ruby:hover , .IRPP_ruby:visited , .IRPP_ruby:active {border:0!important;}.IRPP_ruby .clearfix:after {content: "";display: table;clear: both;}.IRPP_ruby {display: block;transition: background-color 250ms;webkit-transition: background-color 250ms;width: 100%;opacity: 1;transition: opacity 250ms;webkit-transition: opacity 250ms;background-color: #eaeaea;}.IRPP_ruby:active , .IRPP_ruby:hover {opacity: 1;transition: opacity 250ms;webkit-transition: opacity 250ms;background-color: inherit;}.IRPP_ruby .postImageUrl {background-position: center;background-size: cover;float: left;margin: 0;padding: 0;width: 31.59%;position: absolute;top: 0;bottom: 0;}.IRPP_ruby .centered-text-area {float: right;width: 65.65%;padding:0;margin:0;}.IRPP_ruby .centered-text {display: table;height: 130px;left: 0;top: 0;padding:0;margin:0;padding-top: 20px;padding-bottom: 20px;}.IRPP_ruby .IRPP_ruby-content {display: table-cell;margin: 0;padding: 0 74px 0 0px;position: relative;vertical-align: middle;width: 100%;}.IRPP_ruby .ctaText {border-bottom: 0 solid #fff;color: #0099cc;font-size: 14px;font-weight: bold;letter-spacing: normal;margin: 0;padding: 0;font-family:'Arial';}.IRPP_ruby .postTitle {color: #000000;font-size: 16px;font-weight: 600;letter-spacing: normal;margin: 0;padding: 0;font-family:'Arial';}.IRPP_ruby .ctaButton {background: url(https://www.anthropocenemagazine.org/wp-content/plugins/intelly-related-posts-pro/assets/images/next-arrow.png)no-repeat;background-color: #afb4b6;background-position: center;display: inline-block;height: 100%;width: 54px;margin-left: 10px;position: absolute;bottom:0;right: 0;top: 0;}.IRPP_ruby:after {content: "";display: block;clear: both;}Recommended Reading:Mix.

Remove Nanoplastics. But natural evolution might have a jump on human ingenuity. Since the ocean is home to a staggering number of microorganisms (one estimate puts it at more than 100 octillion), it’s also an ideal evolutionary laboratory.

Duarte and a group of fellow scientists went scouting for genetic markers of PET-degrading bacteria in 415 water samples pulled from ocean waters around the world during two expeditions. They found genetic sequences associated with production of a PETase in more than 75% of the samples, the scientists reported earlier this year in The ISME Journal, a publication of the International Society for Microbial Ecology.

“The range of PET-degrading enzymes spontaneously evolved in the deep sea provides models to be optimized in the lab for use in efficiently degrading plastics,” said Duarte. A combination of lab experiments and computer-powered date crunching helped them narrow in specific PETase-related genetic sequences that held the most promise for effectively breaking down the plastic.

They were still abundant, turning up in most of the water samples. But that doesn’t mean it’s an easy solution for dealing with all the plastics we pour into the ocean, Duarte cautioned. “By the time plastics reach the deep sea, the risks to marine life and human consumers have already been inflicted.” Alam, et. “Widespread distribution of bacteria containing PETases with a functional motif across global oceans.” The ISME Journal.

June 10, 2025. Image: ©Anthropocene Magazine