Regulation of alkaline metalloprotease promoter by N-acyl homoserine lactone quorum sensing in Pseudomonas fluorescens
Bibliographic record
Abstract
AIMS: To examine the involvement of N-acyl homoserine lactone (AHL) quorum sensing in alkaline metalloprotease (aprX) promoter regulation in a Pseudomonas fluorescens milk isolate. METHODS AND RESULTS: N-acyl homoserine lactone signals from P. fluorescens strain 395 were separated and detected by thin layer chromatography (TLC). Further analysis of the AHL signals using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) indicated the presence of C4-HSL and 3OC8-HSL. The expression of aprX in P. fluorescens 395 was investigated, using a transcriptional fusion between the aprX promoter and a mutated gfp variant gene (gfp[mut3]). The results demonstrated that the activity of the aprX promoter increased dramatically in the late exponential phase of growth, indicating growth phase-dependent regulation. The activity was repressed in an AHL-deficient environment, in which the signal molecules were hydrolysed by the enzyme AHL lactonase. CONCLUSIONS: N-acyl homoserine lactones produced by P. fluorescens 395 were identified to be C4-HSL and 3OC8-HSL. The protease gene in P. fluorescens is regulated by the AHL-based quorum sensing system at a transcriptional level during the late exponential growth phase. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to our understanding of the genetic regulation and ecology of P. fluorescens in the economically important system of food spoilage.
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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 | 0.001 | 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".