Poly(L-lactide) mineralisation under environmental conditions is enhanced in earthworm guts

authored by

Linda Hink, Stephan Rohrbach, Joey Rehkopf, Elmar Sehl, Seema Agarwal, Heike Feldhaar, Marcus A. Horn

Abstract

Microplastic accumulates in various habitats, posing a potential environmental threat. Biodegradable polymers like poly(L-lactide) (PLLA) is a possible eco-friendly alternative to conventional, non-biodegradable plastics. However, biodegradation of PLLA in soil is strongly limited, but is potentially enhanced by soil-dwelling organisms. We recently showed that PLLA exposure positively affected reproduction in the earthworm Eisenia fetida, and increased gut lactate concentrations, indicating the hypothesis of earthworm-enhanced PLLA biodegradation. Thus, 13C-labelled PLLA was used for a 13CO2-tracing approach to monitor PLLA mineralisation in presence and absence of the earthworm E. fetida. Mineralisation of 0.2% of initial PLLA was attributed to the activity of earthworms after two weeks of exposure. Extrapolation assuming zero-order kinetics and limitation of microbial growth suggested a substantially shorter half-life of PLLA in earthworm-amended soils. This finding provides strong evidence that conditions inside the earthworm gut are beneficial for PLLA degradation and provide a basis for the development of mitigation strategies for PLLA microplastic pollution.

Organisation(s)

Institute of Microbiology

External Organisation(s)

University of Bayreuth

Type

Article

Journal

Soil Biology and Biochemistry

Volume

196

ISSN

0038-0717

Publication date

09.2024

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Soil Science, Microbiology

Electronic version(s)

https://doi.org/10.1016/j.soilbio.2024.109485 (Access: Open)