Transmission electron microscopy (TEM) image of Rhodococcus aetherivorans BCP1 cells grown on naphthenic acids. The electron-dense intracellular body represents a possible polyP granule (from Presentato et al. 2018a). From: Biotechnology of Rhodococcus for the production of valuable compounds
Article: Science Daily
Laboratory experiment shows that bacteria really eat and digest plastic
- January 23, 2023
- Royal Netherlands Institute for Sea Research
- The bacterium Rhodococcus ruber eats and actually digests plastic.
The bacterium Rhodococcus ruber eats and actually digests plastic. This has been shown in laboratory experiments by PhD student Maaike Goudriaan at Royal Netherlands Institute for Sea Research (NIOZ). Based on a model study with plastic in artificial seawater in the lab, Goudriaan calculated that bacteria can break down about one percent of the fed plastic per year into CO2 and other harmless substances. “But,” Goudriaan emphasizes, “this is certainly not a solution to the problem of the plastic soup in our oceans. It is, however, another part of the answer to the question of where all the ‘missing plastic’ in the oceans has gone.”
Goudriaan had a special plastic manufactured especially for these experiments with a distinct form of carbon (13C) in it. When she fed that plastic to bacteria after pretreatment with “sunlight” — a UV lamp — in a bottle of simulated seawater, she saw that special version of carbon appear as CO2 above the water. “The treatment with UV light was necessary because we already know that sunlight partially breaks down plastic into bite-sized chunks for bacteria,” the researcher explains.
Proof of principle
“This is the first time we have proven in this way that bacteria actually digest plastic into CO2 and other molecules,” Goudriaan states. It was already known that the bacterium Rhodococcus ruber can form a so-called biofilm on plastic in nature. It had also been measured that plastic disappears under that biofilm. “But now we have really demonstrated that the bacteria actually digest the plastic.”
When Goudriaan calculates the total breakdown of plastic into CO2, she estimates that the bacteria can break down about one percent of the available plastic per year. “That’s probably an underestimate,” she adds. “We only measured the amount of carbon-13 in CO2, so not in the other breakdown products of the plastic. There will certainly be 13C in several other molecules, but it’s hard to say what part of that was broken down by the UV light and what part was digested by the bacteria.”
Even though marine microbiologist Goudriaan is very excited about the plastic-eating bacteria, she stresses that microbial digestion is not a solution to the huge problem of all the plastic floating on and in our oceans. “These experiments are mainly a proof of principle. I see it as one piece of the jigsaw, in the issue of where all the plastic that disappears into the oceans stays. If you try to trace all our waste, a lot of plastic is lost. Digestion by bacteria could possibly provide part of the explanation.”
From lab to mudflats
To discover whether ‘wild’ bacteria also eat plastic ‘in the wild’, follow-up research needs to be done. Goudriaan already did some pilot experiments with real sea water and some sediment that she had collected from the Wadden Sea floor. “The first results of these experiments hints at plastic being degraded, even in nature,” she says. “A new PhD student will have to continue that work. Ultimately, of course, you hope to calculate how much plastic in the oceans really is degraded by bacteria. But much better than cleaning up, is prevention. And only we humans can do that,” Goudriaan says.
Sunlight pulps the plastic soup
Recently Goudriaan’s colleague Annalisa Delre published a paper about sun light which breaks down plastics on the ocean’s surfaces. Floating microplastic is broken down into ever smaller, invisible nanoplastic particles that spread across the entire water column, but also to compounds that can then be completely broken down by bacteria. This is shown by experiments in the laboratory of NIOZ, on Texel.
In the latest issue of Marine Pollution Bulletin, PhD student Annalisa Delre and colleagues calculate that about two percent of visibly floating plastic may disappear from the ocean surface in this way each year. “This may seem small, but year after year, this adds up. Our data show that sunlight could thus have degraded a substantial amount of all the floating plastic that has been littered into the oceans since the 1950s,” says Delre.
- Maaike Goudriaan, Victor Hernando Morales, Marcel T.J. van der Meer, Anchelique Mets, Rachel T. Ndhlovu, Johan van Heerwaarden, Sina Simon, Verena B. Heuer, Kai-Uwe Hinrichs, Helge Niemann. A stable isotope assay with 13C-labeled polyethylene to investigate plastic mineralization mediated by Rhodococcus ruber. Marine Pollution Bulletin, 2023; 186: 114369 DOI: 10.1016/j.marpolbul.2022.114369
“We MUST respect this earth - it is all we have
Claudio Dametto - South Australia
“I will always Vote to Preserve Our World.
Liam McGregor - Western Australia
“A simple message that even a politician can understand
Felicity Crombach - Victoria
“Please show you care about our future generations!!
Phil Harmer - New South Wales
“Save our world , Life & health before profits.
Kerry Lillian - New South Wales
“Close down all coal mines and Do not mine gas . Make these Companies
Daniel Johnson - New South Wales
“We want carbon free energy!
Edan Clarke - New South Wales
“Feels good to be taking a voter action step
Beaver Hudson - New South Wales
“Great Initiative. Let’s Hold elected officials Accountable to their bosses, us!
John Paul Posada - New South Wales
“We need actions not words we need honest democratic govt We need a pm
Bob Pearce - South Australia
“Thank you for this great resource. I was feeling helpless. Even this small step
Silvia Anderson - Victoria
“If political parties continue receiving political donations, we will rarely have politicians working for
Dan Chicos - New South Wales
“I only vote for people who will take urgent action to restore a safe
Susie Burke - Victoria
“Current government is not representing the opinion of the majority of Australian to meet
Neil Price - Tasmania
“We are fighting to rescue our kids' future from those who seek to steal
Vanessa Norimi - Queensland
“No time to waste Now or Never My vote is for NOW
Rosalie White - Victoria
“I am only 9 but I already care
Ava Bell - New South Wales
“From New Lambton Uniting Church - Caring for our world is a moral imperative.
Niall McKay - New South Wales
“Our federal govt is an International climate Embarrassment - its about time they stepped
Oriana Tolo - Victoria
“Vote earth this time!
Sue Cooke - Queensland
“We are in one on the wealthiest countries in the world. we have the
rowan huxtable - New South Wales
“The climate Emergency is the public health opportunity and urgent priority of the 21st
Mike Forrester - Victoria
“If they want my vote they better act now
Barbara McNiff - New South Wales
“We need to act locally now for the earth. Our only home. Vote Earth
Anne Miller - New South Wales
“I often look at the places I've known all my life and see how
Jim Baird - New South Wales
“Strike one For people power!!! Democracy might prevail outside the current cronyism that faces
Lorraine Bridger - New South Wales
“Our federal politicians Are Afraid to make action on climate change a major election
Jennifer Martin - New South Wales
“climate election, let's go!
Fahimah Badrulhisham - New South Wales
“Great to see this website that is a focus on action for climate change
Lynette Sinclair - New South Wales
“Let’s show politicians and the Murdoch media that climate change is by far the
Jane Aitken - Australian Capital Territory
“If you want to stay in power You need to take action to stop
Jane Bulter - New South Wales
“We are all that stands between terminal climate change and the vulnerable. We are
Carol Khan - Queensland
“We need a Government that Believes this is real and not taking money from
Ken Gray - New South Wales
“I'm voting for my childrens future
Anneliese Alexander - New South Wales