Effect of a BlpC-Based Quorum-Sensing Induction Peptide on Bacteriocin Production in Streptococcus thermophilus
Bibliographic record
Abstract
<p>Bacteriocin synthesis in some <em>Streptococcus thermophilus</em> strains is under the control of a complex <em>blp</em> locus but bacteriocin is produced only when a quorum-sensing regulatory mechanism is activated by the protein product of the <em>blpC</em> component. To demonstrate the regulatory effect of BlpC in <em>S. thermophilus</em> ST110 (NRRL-B59671), which naturally produces bacteriocin, the effect of the 30mer quorum-sensing induction peptide (QSIP) embedded in BlpC was tested in a knockout mutant in which the <em>blpC</em> gene was eliminated and was devoid of antimicrobial activity. Between concentrations of 30 and 250 ng/ml, the addition of synthetic QSIP to cultures at several points of the growth curve resulted in the accumulation of up to 3,200 units/ml of bacteriocin after 8 h of growth at 37 ºC. Addition of QSIP to the culture in late log phase (OD<sub>660</sub> ? 1.0) when the medium pH is already 4.8 or lower, failed to trigger bacteriocin production. We used synthetic QSIP to survey its impact on 35 strains of <em>S. thermophilus</em> that do not display bacteriocin activity by agar diffusion assays. The addition of QSIP (250 ng/ml) to <em>S. thermophilus</em> cultures in the early or mid-log phase induced bacteriocin production in two strains that could be re-classified as bacteriocin producers. The results demonstrated the involvement of a quorum-sensing regulatory mechanism in bacteriocin synthesis in <em>S. thermophilus</em> ST110 and also demonstrated the utility of the 30 mer QSIP in discovering bacteriocins with potentially novel antimicrobial spectra by enhancing bacteriocin production in other strains of <em>S. thermophilus </em>that ordinarily display a bacteriocin-negative phenotype.</p>
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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 | 0.004 | 0.001 |
| 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 | 0.001 |
| 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".