From discovering plastic-eating bacterium to finding a new catalytic process in soils, the Aristilde Research Group had a busy year in 2024. It published seven papers and submitted four more for review by academic journals.
The lab researches biochemical and microbial processes in soil and water systems. Researchers aim for these processes to be used as a basis for nature-based solutions to environmental issues, the group’s principal investigator Ludmilla Aristilde said.
The latest discovery was that a type of bacterium found in wastewater can break down polyethylene terephthalate — or PET — plastic. The bacterium is called Comamonas testosteroni. Not only did members of the Aristilde Research Group document Comamonas breaking down PET plastic, but they also discovered how this process occurs.
“The bulk of the paper that has to demonstrate that it degrades plastic — that part was easy,” Aristilde said. “Understanding how it does it, that’s the part that required more work.”
The work included finding and modeling the specific protein in the bacterium’s cells that can break down PET plastic. Scientific journal Environmental Science and Technology published the research in October 2024 and it took over two years to complete.
Although other bacterium have been observed breaking down plastics, Comamonas is unique in its ability to use the carbon in the degraded pieces to grow.
Postdoctoral researcher Nanqing Zhou was one of the two first authors and said it was exciting to watch the experiment progress. She said it became “more and more obvious” that the plastic is disappearing in the petri dish of bacterium over time.
Zhou is not only interested in how bacterium can use carbon from plastic but also whether they can be modified to do so more efficiently.
“It is important that we figure out the whole pathway of how this bacterium processes this complex carbon source, i.e. PET plastics, and then we give a hint of where we can start manipulating (the bacterium) to make it a better plastic degrader,” Zhou said.
Zhou said she hopes to expand the study to other types of plastics.
Over the summer, the lab also published its discovery of a new catalytic process in soil that converts a form of phosphorus found in the soil into a form that plants can absorb.
Aristilde’s lab discovered iron oxide — a compound found in some soils, which makes the surface of Mars red — can convert phosphorus into the form plants need. This finding could impact agriculture in the future, Aristilde said.
Jade Basinski (McCormick ’24) was the first author of this paper, and soil research was the basis for her Ph.D., which she earned in December from Northwestern.
“Phosphorus can be really hard to find in the environment,” Basinski said. ”What I’m trying to do is to essentially make the phosphorus that we need to feed the plants, and the plants feed us.”
Soil science does not get the same attention as other areas of environmental science, like carbon capture, Basinski said. However, she added this is one of the rewarding aspects of her research: investigating the importance of something that “nobody cares about.”
The lab recently finished “benchmarking” the process in which iron oxide catalyzes the reaction that turns an unusable form of phosphorus into a usable form for plants. While the first paper showed that this process happened, the next step was to quantify the steps.
A research journal accepted the second paper this month. According to Aristilde, it will be published in a few weeks.
“In my lab, we are very excited about what are the new things out there — the new biochemistry, the new catalytic processes, that are already in nature that we haven’t discovered yet,” Aristilde said. “That to me, it’s my lifetime’s work and beyond my lifetime’s work.”
Correction: A previous version of this story incorrectly used the plural form “bacteria,” implying that the Aristilde Lab was studying multiple bacteria. The lab is studying a singular bacterium. The Daily regrets this error.
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