Biodegradation of p-xylene – A comparison for three Cold-active Pseudomonas strains
Bibliographic record
Abstract
Abstract p-xylene is considered a recalcitrant compound despite the similar aromatic structure with BTE (Benzene, toluene, ethylbenzene). This study evaluated the biodegradation potential of p-xylene by three cold-active Pseudomonas strains (named Pseudomonas putida S2TR-01, Pseudomonas S2TR-20, and Pseudomonas S2TR-09). The catabolic genes (xylM, xylA and xylE) and their regulatory genes (xylR and xylS) were investigated for the p-xylene metabolism. The biodegradation results showed that only strain S2TR-09 was able to degrade 200 mg/L of p-xylene after 60 h at 15 °C. The gene expression study indicated that xylE (encoding catechol 2, 3-dioxygenase) represents the bottleneck for p-xylene biodegradation and lack of its expression leads to the accumulation of intermediates and inhibits biomass production as well as carbon recovery. The activity of xylene monooxygenase and catechol 2,3 dioxygenase was significantly high in P. azotoformans S2TR-09 (0.5 and 0.08 U/mg) in the presence of p-xylene. The expression of ring cleavage enzyme, its encoding genes (xylE), and its activator (xylS) enabled to link the differences in p-xylene metabolism and can be used as a novel biomarker for efficient p-xylene biodegradation in contaminated sites.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".