Mercury methylation and hydrogen sulfide production among unexpected strains isolated from periphyton of two macrophytes of the Amazon
Bibliographic record
Abstract
The periphyton of macrophytes had previously been identified as important spots for mercury methylation in the Amazon basin, but the microorganisms that facilitate methylation in such compartment are still to be identified. Here, bacteria were isolated from periphyton associated with Eichhornia crassipes and Polygonum densiflorum in Widdel and Pfennig medium and tested for mercury methylation with a stable isotope tracer technique using (198)HgCl, hydrogen sulfide production and molybdate inhibition. Three Pleomorphomona spp., one unidentified Deltaproteobacteria, two Klebsiella spp., and one Tolumonas sp. were isolated. All except Tolumonas sp. were able to methylate mercury (up to 5% of the (198)HgCl added) and produce up to 4 mM of H(2)S, while the Deltaproteobacteria was also able to demethylate methylmercury. Although these bacteria may not be as strong mercury methylators as sulfate-reducing bacteria, they have the potential to contribute to methylmercury accumulation in the system.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".