Turkey tail mushroom (Trametes versicolor)
Photo Credit: Johan Doe
Scientific Frontline: Extended "At a Glance" Summary: Mycoaugmentation for Pharmaceutical Residue Reduction
The Core Concept: Mycoaugmentation involves the application of white-rot fungi, such as oyster (Pleurotus ostreatus) and turkey tail (Trametes versicolor) mushrooms, to degrade and neutralize persistent psychoactive pharmaceutical residues found in biosolids, the nutrient-rich byproducts of wastewater treatment.
Key Distinction/Mechanism: Unlike conventional wastewater treatments or targeted bacterial remediation, white-rot fungi release powerful, nonspecific enzymes directly into their surroundings. Originally evolved to decompose tough lignin in wood, these highly flexible enzymes chemically transform a wide array of complex drug compounds tightly bound to organic matter, cleaving them into smaller, safely detoxified molecules.
Major Frameworks/Components:
- Enzymatic Flexibility: The utilization of nonspecific extracellular enzymes capable of breaking down highly varied and complex organic pollutants without targeting a single compound.
- Real-World Matrix Testing: A methodological framework emphasizing the testing of degradation processes directly within solid environmental matrices (biosolids) rather than isolated, liquid laboratory cultures, ensuring accurate real-world efficacy.
- True Detoxification: The chemical transformation of active pharmaceuticals via molecular cleavage and oxygenation, resulting in more than 40 identified byproducts with significantly lower toxicity profiles, as opposed to simply trapping or redistributing the contaminants.
- Mycoaugmentation: The deliberate introduction of selected fungal species into polluted environments or waste streams to facilitate ecological bioremediation.
Branch of Science: Environmental Engineering, Bioremediation, Mycology, and Environmental Chemistry.
Future Application: This biological treatment method can be integrated into existing municipal wastewater and biosolids management systems. Due to its low energy and infrastructure requirements, fungi could routinely pretreat nutrient-rich biosolids prior to their distribution, ensuring safe application as agricultural fertilizer.
Why It Matters: Biosolids are widely utilized across the United States as agricultural fertilizers, but conventional wastewater treatments consistently fail to eliminate complex psychoactive drugs. Utilizing fungi to detoxify these fertilizers prevents trace pharmaceuticals from accumulating in soils, protecting aquatic ecosystems from toxic runoff and mitigating potential public health risks associated with our agricultural infrastructure.
Antidepressants and other psychoactive drugs are designed to affect the human brain. But after they enter the water system in excrement or unused drugs flushed down the drain, traces of these compounds can enter the environment in biosolids—the nutrient-rich material left over after wastewater treatment that is used as fertilizer. New research suggests an unexpected mitigation strategy: using wood-rotting fungi that can break down these chemicals before they reach soil, crops, and people.
Conventional wastewater treatment methods are effective at killing pathogens and reducing metals, but they are far less successful at neutralizing complex organic chemicals. This limitation prompted the research team to explore new, low-cost, and sustainable approaches to reducing pharmaceutical contamination before biosolids are applied to croplands.
Researchers in the Johns Hopkins Department of Environmental Health and Engineering, which spans the Bloomberg School of Public Health and the Whiting School of Engineering, have shown that two species of "white-rot" fungi—oyster and turkey tail mushrooms—can degrade a wide range of psychoactive pharmaceuticals commonly found in biosolids. The study demonstrates that these fungi can break down many persistent drug compounds before biosolids are applied to farmland, potentially reducing environmental and public health risks.
Biosolids are widely used across the United States as fertilizers and soil conditioners because they are rich in nitrogen, phosphorus, and organic matter.
While some studies have shown that pharmaceuticals can be absorbed by plants grown in biosolids-amended soils or irrigated with wastewater, there is no conclusive evidence that these chemicals reach people who consume those crops.
"Even small concentrations of these compounds can have psychological effects when consumed, which is why they have become contaminants of concern," says Kate Burgener, a PhD student and lead author of the study. "Many of them are also difficult to break down and can persist in the environment, where they may have toxic effects on aquatic life."
The researchers focused on white-rot fungi, a group of fungi known for their ability to decompose lignin—the tough polymer that gives wood its rigidity. Unlike many bacteria, white-rot fungi release powerful enzymes directly into their surroundings. These enzymes are "nonspecific," meaning they can act on a wide range of complex molecules rather than targeting a single compound.
It is their enzymatic flexibility that makes white-rot fungi well-suited for breaking down pharmaceuticals, which are tightly bound to organic matter in biosolids.
The two species—Pleurotus ostreatus (oyster mushroom) and Trametes versicolor (turkey tail)—are among the most studied and most widely available mushroom species. Biosolids from a municipal wastewater treatment plant were spiked with nine psychoactive drugs, including commonly used antidepressants such as citalopram and trazodone. The fungi were then allowed to grow directly on the biosolids for up to 60 days.
To better understand how fungal growth conditions influenced degradation, the researchers conducted parallel experiments in liquid media without biosolids. Using high-resolution mass spectrometry, they measured drug concentrations over time and identified chemical byproducts formed as the fungi broke the compounds down. Some compounds degraded more in the biosolids experiments than in liquid culture.
"Even small concentrations of these compounds can have psychological effects when consumed, which is why they have become contaminants of concern."Kate BurgenerPhD student
"While it is promising when liquid fungal culture degrades a compound, it doesn't necessarily mean that's what will happen when you grow the fungi in a polluted environment," says Burgener. "So we decided to test a relevant medium—in this case biosolids—that gets contaminated with psychoactive chemicals with the fungi to see if fungi break down these contaminants before they are spread in the environment."
Both fungal species proved highly effective. Each degraded eight of the nine pharmaceuticals tested, with removal rates ranging from approximately 50% to nearly complete elimination after two months. Pleurotus ostreatus was particularly effective, removing more than 90% of several antidepressants.
Chemical analyses showed that the fungi were not simply trapping the drugs but chemically transforming them. The researchers identified more than 40 products formed as the pharmaceutical molecules were broken apart. Many of these reactions—such as cleavage into smaller molecules or the addition of oxygen—are characteristic of white-rot fungal enzymes.
Using the EPA's Cheminformatics hazard assessment module, the researchers predicted that most of the transformation products would be less toxic than the original drugs, suggesting that fungal treatment may reduce overall hazard rather than replace one contaminant with another.
The findings highlight "mycoaugmentation"—the intentional use of fungi—as a promising strategy for treating biosolids prior to land application. Because white-rot fungi are widespread in nature and can grow on solid materials, they could potentially be integrated into existing biosolids management practices with relatively low energy and infrastructure requirements.
"The fungi represent a promising bioaugmentation strategy on a real-world matrix, not just lab-based liquid culture," Burgener says.
On a personal note, Burgener prefers her mushrooms in the laboratory rather than on her plate.
"I don't find them especially appetizing," she says. "They're good for you, so sometimes if they're doused in butter, I'll eat them."
The study was co-authored by Carsten Prasse, associate professor in the Department of Environmental Health and Engineering. It was supported by a
Funding: U.S. Environmental Protection Agency National Priorities grant (R840247) and Johns Hopkins University.
Published in journal: ACS Environmental Au
Title: Magic Mushrooms? White-Rot Fungal Degradation of Psychoactive Pharmaceuticals in Biosolids
Authors: Kate Burgener, and Carsten Prasse
Source/Credit: Johns Hopkins University | Danielle Underferth
Reference Number: env031926_01
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