TY - JOUR

T1 - Poly(L-lactide) mineralisation under environmental conditions is enhanced in earthworm guts

AU - Hink, Linda

AU - Rohrbach, Stephan

AU - Rehkopf, Joey

AU - Sehl, Elmar

AU - Agarwal, Seema

AU - Feldhaar, Heike

AU - Horn, Marcus A.

N1 - Publisher Copyright: © 2024 The Authors

PY - 2024/9

Y1 - 2024/9

N2 - 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.

AB - 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.

KW - C-PLLA polymerisation

KW - C-tracing

KW - Eisenia fetida

KW - Microplastic

KW - Mineralisation rate

KW - PLLA

KW - Soil

UR - http://www.scopus.com/inward/record.url?scp=85195268061&partnerID=8YFLogxK

U2 - 10.1016/j.soilbio.2024.109485

DO - 10.1016/j.soilbio.2024.109485

M3 - Article

VL - 196

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

SN - 0038-0717

M1 - 109485

ER -