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Updated: Jun 29, 2026

Sampling, Sorting, and Characterizing Microplastics in Aquatic Environments with High Suspended Sediment Loads and Large Floating Debris
Published on: July 28, 2018
Density-mediated freshwater plastisphere microbiomes preferentially degrade conventional rather than biodegradable
Haiyu Zhang1,2, Peng Liu1, Yiqi Chen1
1State Key Laboratory of Soil and Water Conservation and Desertification Control, College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China.
None:
The escalating demand for plastics leads to ubiquitous microplastic (MP) pollution worldwide. Existing evidence suggests that biodegradable MPs degrade faster than conventional MPs in aquatic environments. Here, we demonstrate the greater biodegradability of conventional polypropylene (PP) over biodegradable polylactic acid (PLA) in freshwater based on field survey, mesocosm experiment, co-culture assay, and multi-omics analysis. The biodegradation rate is 3.3-fold higher for PP compared to PLA, and this difference is more pronounced between photoaged MPs (5.7-fold). The unexpected superior biodegradability of PP is supported by a greater diversity of MP-degrading bacteria in PP biofilm (predominantly aerobes) than in PLA biofilm (mainly facultative and obligate anaerobes). The inferior biodegradability of PLA is attributed to microbial growth constraints in the plastisphere driven by oxic-to-hypoxic/anoxic transition, oxygen-containing functional group detachment from the polymer, and lactide accumulation during long-term biodegradation. Our findings reveal previously overlooked but important environmental fates and impacts of biodegradable plastics against increasing substitution of conventional plastics with biodegradable alternatives.
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