Polyhydroxybutyrate Plastics Show Rapid Disintegration and More Straightforward Biogeochemical Impacts than Polyethylene under Marine Biofragmentation
Bibliographic record
Abstract
Although massive studies have investigated the spatiotemporally occurring marine plastisphere, a new microbial ecosystem colonizing the surfaces of plastics, the resulting biofragmentation process and impacts of plastics on biogeochemical cycles remain largely unknown. Here, we leverage synchrotron-based Fourier transform infrared spectromicroscopy (FTIR mapping) and metagenomic sequencing to explore independent marine microcosms amended with petroleum-based polyethylene (PE) and biobased polyhydroxybutyrate (PHB) plastic films. FTIR mapping results demonstrate unequal fragmentation scenarios by which the PE plastic rarely releases oxidized fragments while PHB disintegrates quickly, gradually forming fragments composed of extracellular polymeric substances resembling plastic films. Metagenomic analysis shows the critical role of hydrocarbonoclastic lineages in the biodegradation of the two plastics by the fatty acid degradation pathway, where the PE plastics host different microbial trajectories between the plastisphere (dominated by Alcanivorax ) and surrounding seawater. In contrast, the PHB addition demonstrates decreased microbial richness and diversity, consistent community composition (dominated by Phaeobacter and Marinobacter ), and apparently stimulated sulfur cycle and denitrification pathways in both the plastisphere and surrounding seawater. Our study gives scientific evidence on the marine biotic processes distinguishing petroleum- and biobased plastics, highlighting marine PHB input exerting straightforward impacts on the water phase and deserving critical management practices.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".