Recovery of<i>Pseudomonas aeruginosa</i>culturability following copper- and chlorine-induced stress
Bibliographic record
Abstract
This study investigated how quickly cells of the opportunistic pathogen Pseudomonas aeruginosa recover culturability after exposure to two of the most common environmental stressors present in drinking water, free chlorine and copper ions. Viable but nonculturable (VBNC) P. aeruginosa undetected by direct culturing following exposure to free chlorine or copper ions can survive in drinking water systems, with potential to recover, multiply, and regain infectivity. Cells were exposed to copper sulfate (0.25 mg Cu(2+) L(-1) ) or free chlorine (initial dose of 2 mg Cl2 L(-1) ) for 24 h. Despite total loss of culturability and a reduction in viability from 1.2 × 10(7) to 4 × 10(3) cells mL(-1) (3.5 log), cells exposed to chlorine recovered viability quickly after the depletion of free chlorine, while culturability was recovered within 24 h. Copper ions did not depress viability, but reduced culturability from 3 × 10(7) to 2.3 × 10(2) cells mL(-1) (5.1 log); VBNC cells regained culturability immediately after copper ion chelation. A comparison between direct culturing and Pseudalert, a specific enzyme-based assay, was performed. Both detection methods were well correlated in the range of 10(2) -10(10) cells L(-1) . However, correlations between the methods declined after exposure to copper ions.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.002 | 0.001 |
| 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".