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Updated: Jan 4, 2026
Antimicrobial Characterization of Advanced Materials for Bioengineering Applications
Published on: August 4, 2018
Environmental fate processes of antimicrobial peptides daptomycin, bacitracins, and polymyxins
Caroline A Davis1, Elisabeth M-L Janssen2
1Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zurich, Switzerland; Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland.
Abstract:
Antimicrobial peptides (AMPs) are increasingly important as a last resort against multi-drug resistant bacteria due to resistance formation towards conventional antibiotics. However, many AMPs were introduced to the market before environmental risk assessment was required, e.g., by the European Medicines Agency (EMA) since 1998. While AMPs have been administered as antibiotics and growth promotors in feedstock since the 1960s and were reconsidered for human medicine by the EMA in 2013, details about their mobility and persistence in the environment remain unknown. This study investigated the environmental fate of three commonly used AMPs: bacitracins, daptomycin, and polymyxins B and E (Colistin). We observed moderate sorption affinity of daptomycin to standard European soils (Kd = 20.6-48.6), while polymyxins adsorbed irreversibly. Bacitracin variants sorbed slightly to sandy soil (Kd = 5.8-8) and significantly to clayey soil (Kd = 169-250). We further investigated photochemical and microbial transformation processes relevant in surface waters. We demonstrated that phototransformation of all AMPs was enhanced in the presence of dissolved organic matter and fast bimolecular reaction rate constant with singlet oxygen contributed largely to indirect phototransformation (15-41%). Phototransformation product analysis for daptomycin was consistent with expected modifications of the tryptophan and kynurenine moieties. Moreover, riverine biofilm communities demonstrated biotransformation potential for all AMPs. Our findings of sorption behaviour, photo- and biotransformation suggest that these processes play a critical role in the fate of bacitracins, daptomycin, and polymyxins in environmental systems.
Insights
Antimicrobial peptides like bacitracins, daptomycin, and polymyxins have varied environmental fates. Sorption, phototransformation, and biodegradation influence their persistence and mobility in ecosystems.
Area of Science:
- Environmental Science
- Microbiology
- Chemistry
Background:
- Antimicrobial peptides (AMPs) are crucial alternatives to conventional antibiotics against multi-drug resistant bacteria.
- Many AMPs were approved before environmental risk assessments were mandatory, raising concerns about their environmental fate.
- Understanding the environmental behavior of AMPs is vital given their historical and current use in medicine and agriculture.
Purpose of the Study:
- To investigate the environmental fate of commonly used AMPs: bacitracins, daptomycin, and polymyxins (B and E/Colistin).
- To assess the sorption behavior of these AMPs in European soils.
- To evaluate the photochemical and microbial transformation processes affecting AMPs in surface waters.
Main Methods:
- Soil sorption experiments using standard European soils to determine distribution coefficients (Kd).
- Phototransformation studies in surface water simulating environmental conditions, including the role of dissolved organic matter and singlet oxygen.
- Biotransformation assays using riverine biofilm communities to assess microbial degradation potential.
Main Results:
- Daptomycin showed moderate sorption (Kd = 20.6-48.6), while polymyxins exhibited irreversible adsorption.
- Bacitracin variants displayed slight sorption to sandy soils (Kd = 5.8-8) and significant sorption to clayey soils (Kd = 169-250).
- Phototransformation was enhanced by dissolved organic matter, with singlet oxygen contributing significantly (15-41%) to indirect phototransformation. Riverine biofilms demonstrated biotransformation capabilities for all tested AMPs.
Conclusions:
- Sorption processes significantly influence the mobility of bacitracins and daptomycin in soils, with polymyxins being largely immobilized.
- Photochemical and microbial degradation are key transformation pathways for AMPs in aquatic environments.
- These findings highlight the critical role of sorption and transformation processes in determining the environmental fate and persistence of widely used antimicrobial peptides.
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