New study reveals bacteria that can eat plastic

Plastic waste is one of the major environmental problems, and the scientific community has always highlighted plastic pollution in oceans and seas, but research into solutions to tackle plastic pollution in freshwaters has been largely neglected.

So scientists from the University of Cambridge conducted a study on the role of bacteria in overcoming plastic waste in freshwater lakes, the results of which were published in Nature Communications on July 26.

Chemical elements that help bacteria grow

The research reported that the chemicals that make up the plastic help bacteria grow faster in the lakes, which the researchers described as a possible successful attempt to remove plastic waste naturally from fresh water.

" The results showed the effect of plastic pollution on fresh water, and it seemed to us that bacterial appetites increased with plastic pollution," University of Cambridge professor of botany and study general supervisor Andrew Tannitzab says in the press release .

Plastics are organic chemicals, which are industrial polymers and the basis of their composition is carbon and hydrogen, such as polyethylene and polypropylene, which are non-degradable materials. Plastic contains other materials that give it its properties, such as artificial colors and plasticizers, which can degrade.

When plastic decomposes, it returns to its original form in the form of simple carbon compounds, but it differs little from those of natural organic materials such as twigs and leaves. The researchers tested the effect of these compounds on bacteria in 29 lakes in Scandinavia.

Plastic and water sample collection

The researchers found that plastic bags are the main source of plastic pollution in lakes, so they chose them for their experiment, which they obtained from 4 major British supermarkets. Plastic bags are usually made of polyethylene and polypropylene, a polymeric material that makes up 34% of the plastic in the market.

The researchers collected samples from 29 lakes between August and September 2019, and their selection of these lakes was based on their difference in geographical location, depth, area, average surface temperature, and the type of organic matter in them.

After that, the researchers put the bags in fresh water, and stirred and stirred the bags inside it so that the molecules of carbon materials from them were released into the water, and they referred to it (plastic water). Then, they brought glass bottles filled with lake samples, and put in half a small amount of plastic water and in the other half added distilled water, and kept the bottles in a dark place for 72 hours.

Experiment results

After 72 hours, the researchers measured the bacterial activity and the efficiency of bacterial growth in the flasks through the amount of carbon dioxide emitted during growth, and they found that the bacteria in the (plastic water) samples increased 2.29 times more than the other samples, and absorbed almost half the amount of the carbon element from the samples. .

Andrew explained that "the results of the study indicate that plastic pollution plays a role in stimulating the entire food web in the lakes, because some organisms such as fish and ducks feed on bacteria, and doubling the size of bacteria means doubling the amount of food for those organisms."

“Our study shows that when plastic bags enter lakes and rivers, they can have dramatic and unexpected effects on the entire ecosystem, and we hope our findings will encourage people to be more careful about their plastic waste disposal,” study lead author Eleanor Sheridan said in the press release. Scientists have warned of the impact of some compounds in plastic on the environment, especially if they are found in high concentrations.

By asking researcher Andrew Tannitzab via e-mail about what these substances are, their impact on aquatic organisms and humans, and how dangerous they are if bacteria feed on them, he told Al Jazeera Net, "We found polluting and worrisome compounds, such as phthalates, which bacteria have already fed, and we have no knowledge to Now how do these types of compounds bioaccumulate in food webs, and the risks they will pose to the health of aquatic organisms as well as to humans."

Phthalates are salts and esters of phthalic acid, which are plasticizers that are added during the manufacture of plastics in order to increase their flexibility, transparency, and life.

Types of bacteria and their effect on plastic waste removal

The results of the study showed that certain genera of bacteria can be exploited to remove plastic waste from the environment, and the effect of bacteria varies depending on their types, and lakes with diverse and different types were better at removing plastic pollution, and researchers found that certain types of bacteria were prevalent in the majority of lakes, such as bacteria stagnant Acinetobacter (Acinetobacter).

And some of these species preferred carbon compounds derived from plastics over natural carbon compounds, and grew 1.72 times more. The researchers attributed the reason to the fact that carbon compounds from plastics are easier for bacteria to break down and use as food. Therefore, if a lake has a high concentration of plastic pollution, but has low bacterial diversity and high natural organic compounds, the expected result is that its ecosystem will be more vulnerable to damage.

"Unfortunately, plastic will pollute our environment for decades, but on the other hand, our research will identify microbes that can be harnessed to help remove plastic waste and better manage the environmental pollution problem," says David Aldridge, a professor in the Department of Zoology at the University of Cambridge and study co-author.