Konstanz biologists find a bacterial enzyme that breaks down bioplastics and penicillin
Several biodegradable plastics broke down fully in soil within about a year while conventional plastic barely changed, Konstanz researchers report. The team also reports an enzyme that breaks down certain polyesters and penicillin.
The Scientist · Science desk
What happened
- The experiments centered on long-chain aliphatic polyesters (LCAP), a biodegradable class developed by a team led by chemist Stefan Mecking.
- For the field test, the team buried small LCAP films about ten centimeters deep in the upper humus layer of forest soil at the university's botanical garden.
- Laboratory tests mixed powdered bioplastics into soil collected from the same forest while the team monitored microbial activity.
- To find candidate enzymes, Harry Lerner and David Schleheck examined the microbial communities and their collective genes, the metagenome.
Why it matters
- What it limits constraint The gain depends on manufacturers switching to materials with bonds microbes can cut, and the conventional plastic in the test barely changed.
- Who has to decide decision Anyone weighing LCAP-type materials for soil disposal has one forest humus layer as evidence and would need to test their own conditions.
- What's now possible capability Searching a working soil community's metagenome gave the team a route from a field result to a candidate plastic-degrading enzyme.
The burial site was chosen for what already lives in it. Harry Lerner said of the upper humus layer: "This layer is where the breakdown of cellulose and other natural polymers, such as cutin - a plant-based polyester - takes place." [7] The team picked the setting because its microorganisms already carry the machinery to break down complex natural materials, according to the University of Konstanz account carried by ScienceDaily [8]. In our view that makes it a fair place to ask whether the plastic can be broken down at all. It also limits how far a one-year figure travels, because both the burial and the laboratory tests drew on the same forest [6].
The comparison that gives the result weight is the conventional plastic, which remained largely unchanged [9]. That fits the background. Microorganisms struggle to digest the synthetic polymers in most conventional plastics, so these materials fragment into microplastics and nanoplastics instead of disappearing [13].
The enzyme is a separate finding. The researchers analyzed the microbial communities and their collective genes to look for enzymes that could break apart plastic polymers [2]. The enzyme they report acts on particular polyesters and biodegradable plastics. It also breaks down penicillin, which the researchers say suggests a possible connection to antibiotic resistance [10]. They add that the discovery suggests bacteria may be adapting to digest certain plastics faster than previously believed [14]. The work appears in The ISME Journal [4].
The thing this doesn't tell you is how much of the buried film's disappearance the enzyme explains.
We'd treat the two findings separately. The material result is the one a producer can act on, subject to the condition the source states: more plastic products would need to be made from biodegradable materials containing chemical bonds microbes can break apart [12]. The enzyme is described for polyesters and biodegradable plastics, while the conventional plastic in the test barely changed [10][9].
What to watch
- The full ISME Journal paper: number of buried samples, the identity of the conventional plastic, and how complete breakdown was measured.
- Experiments that tie the enzyme itself to the disappearance of the buried film.
- Repeats of the burial test in soils and settings beyond one forest humus layer.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence55
- Adoption
- Not scored
- Hype gap+30
- Incentives45
- Confidence60
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Biologists Harry Lerner and David Schleheck studied the entire process of microbial decomposition, to determine whether the materials could be completely broken down, which microorganisms were responsible and what biological mechanisms allowed it.
- [2]
The researchers examined the composition of the microbial communities and analyzed their collective genetic information (the metagenome) to search for genes that might produce enzymes capable of breaking apart plastic polymers.
- [3]
The experiments focused on long-chain aliphatic polyesters (LCAP), a class of biodegradable plastic developed by a research team led by chemist Stefan Mecking.
- [4]
The findings were published in The ISME Journal.
- [5]
The team buried small pieces of LCAP bioplastic film in the upper humus layer of the forest at the university's botanical garden, about ten centimeters deep.
- [6]
Alongside the outdoor experiment, the scientists ran laboratory tests using soil collected from the same forest, mixing powdered bioplastics into the soil and monitoring microbial activity.
- [7]
"This layer is where the breakdown of cellulose and other natural polymers, such as cutin - a plant-based polyester - takes place."
- [8]
The researchers selected the humus environment because its microorganisms already possess the biological machinery needed to break down complex natural materials.
- [9]
Several biodegradable plastics completely broke down in soil within about a year, while conventional plastic remained largely unchanged.
- [10]
Researchers at the University of Konstanz discovered an unusual enzyme that can digest particular polyesters and biodegradable plastics and can also break down penicillin, suggesting a possible connection to antibiotic resistance.
- [11]
The enzyme is nicknamed the Pac-Man enzyme because its structure has a remarkably wide opening, the active site, where chemical reactions take place.
- [12]
For microorganisms to make a meaningful difference in reducing plastic pollution, more plastic products would need to be made from biodegradable materials that contain chemical bonds microbes can break apart.
- [13]
Most conventional plastics break down extremely slowly because microorganisms struggle to digest their synthetic polymers; instead of disappearing they fragment into smaller particles, including microplastics and nanoplastics.
- [14]
The discovery suggests that bacteria may be adapting to digest certain plastic materials more quickly than researchers previously believed.
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Sources
1 independent publisher whose own reporting we read for this story.
- sciencedaily.comScientists discover a plastic-eating “Pac-Man” enzyme with a surprising secret
1 article · October 16, 2026
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Topics
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