Effect of 2,4-dinitrotoluene on the anaerobic bacterial community in marine sediment
Bibliographic record
Abstract
AIMS: To study the impact of added 2,4-dinitrotoluene (DNT) on the anaerobic bacterial community in marine sediment collected from an unexploded ordnance dumping site in Halifax Harbour. METHODS AND RESULTS: Marine sediment was spiked with 2,4-DNT and incubated under anaerobic conditions in the presence and absence of lactate. Indigenous bacteria in the sediment removed 2,4-DNT with subsequent formation of its mono- and diamino-derivatives under both conditions. PCR-DGGE and nucleotide sequencing were used to monitor the change in the bacterial population in sediment caused by the presence of 2,4-DNT. The results showed that denaturing gradient gel electrophoresis banding patterns of sediment microcosms treated with 2,4-DNT were different from controls that did not receive 2,4-DNT. Bacteroidetes, Firmicutes and delta-Proteobacteria were present in sediment incubated in the absence of 2,4-DNT. However, several gamma-Proteobacteria became dominant in sediment in the presence of 2,4-DNT, two of which were 99% similar to Shewanella canadensis and Shewanella sediminis. In the presence of both 2,4-DNT and lactate, two additional delta-Proteobacteria were enriched, one closely related (98% similarity) to Desulfofrigus fragile and the other affiliated (96% similarity) to Desulfovibrio sp. In contrast, none of the above four Proteobacteria were enriched in sediment incubated with lactate alone. CONCLUSIONS: Presence of 2,4-DNT led to a significant change in bacterial population of marine sediment with the enrichment of several gamma- and delta-Proteobacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results provided the first evidence on the impact of the pollutant 2,4-DNT on the indigenous bacterial community in marine sediment, and provided an insight into the composition of bacterial community that degrade 2,4-DNT.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 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 | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 teacher head, 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".