Effect of a BlpC-Based Quorum-Sensing Induction Peptide on Bacteriocin Production in Streptococcus thermophilus
Bibliographic record
Abstract
Bacteriocin synthesis in some Streptococcus thermophilus strains is under the control of a complex blp locus but bacteriocin is produced only when a quorum-sensing regulatory mechanism is activated by the protein product of the blpC component. To demonstrate the regulatory effect of BlpC in S. thermophilus 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 blpC 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 (OD660 ? 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 S. thermophilus that do not display bacteriocin activity by agar diffusion assays. The addition of QSIP (250 ng/ml) to S. thermophilus 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 S. thermophilus 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 S. thermophilus that ordinarily display a bacteriocin-negative phenotype.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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) | 0.001 | 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".