Degradation of brown coal and 1-methylnaphthalene by a <i>Micrococcus luteus</i> isolate: investigation of a novel aromatic degradation gene cluster containing <i>paa</i> genes
Bibliographic record
Abstract
AIMS: To identify novel brown coal-degrading bacteria, and elucidate the biochemical pathways involved in brown coal degradation. METHODS AND RESULTS: Four bacterial isolates were identified from the surface of Indonesian brown coal, which can utilize naphthalene and 1-methylnaphthalene as carbon sources for growth. The genome sequence of the best-performing Micrococcus luteus K1 strain was determined. A novel aromatic degradation gene cluster was identified, containing several paa genes normally involved in phenylacetic acid degradation, and also containing genes found on aromatic meta-cleavage pathways. 1-Naphthoic acid was generated from 1-methylnaphthalene by M. luteus K1 whole cell biotransformation, and was also utilized as a growth substrate by M. luteus K1. Recombinant ligase PaaK from the new gene cluster was shown to activate either phenylacetic acid or 1-naphthoic acid to their respective CoA esters, consistent with 1-naphthoyl CoA being an intermediate on the pathway. From metabolite analysis and annotation of the gene cluster, a new 1-methylnaphthalene degradation pathway was proposed, via a benzene oxide-oxepin ring opening. Recombinant mono-oxygenase and extradiol catechol dioxygenase enzymes from the gene cluster were expressed, showing activities consistent with the later steps of the proposed pathway. CONCLUSIONS: A new M. luteus K1 isolate was identified as a brown coal degrader, whose genome contains an unusual aromatic degradation cluster containing paa genes. This cluster is hypothesized to be responsible for 1-methylnaphthalene degradation.
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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) | 0.000 | 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 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".