Bacterial metabolism of fluorene, dibenzofuran, dibenzothiophene, and carbazole
Bibliographic record
Abstract
Fluorene and its three heteroatomic analogs, dibenzofuran, dibenzothiophene, and carbazole, are environmental contaminants in areas impacted by spills of creosote. In addition, dibenzofuran has been used as an insecticide, and it is formed from the photolysis of chlorinated biphenyl ethers. Many biodegradation studies of dibenzofuran have considered it as a model for chlorinated dibenzofurans, which are of greater environmental concern. This paper reviews the bacterial degradation of fluorene and its analogs. These compounds are susceptible to three different modes of initial oxidation: (i) the naphthalene-like attack, in which one of the aromatic rings is oxidized to a dihydrodiol; (ii) an angular dioxygenase attack, in which the carbon bonded to the methylene group in fluorene or to the heteroatoms in the analogs, and the adjacent carbon in the aromatic ring are both oxidized; and (iii) the five-membered ring attack, in which the methylene carbon atom in fluorene or the sulfur atom in dibenzothiophene is oxidized. The metabolites, enzymology, and genetics of these transformation are summarized. Literature data are presented, indicating that the electronegativity of the atom connecting the two aromatic rings influences the attack of the angular dioxygenase. In dibenzofuran and carbazole, the connecting atoms, O and N respectively, have high electronegativities, and these compounds serve as substrates for angular dioxygenases. In contrast, the connecting atoms in dibenzothiophene and fluorene, S and C respectively, have lower electronegativities, and these atoms must be oxidized before the angular dioxygenases attack these compounds.Key words: angular dioxygenase, carbazole, dibenzofuran, dibenzothiophene, fluorene.
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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 | 0.000 | 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.016 | 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".