DEVELOPMENT OF A MULTIWELL ANTAGONISTIC ACTIVITY ASSAY FOR THE DETECTION OF BACTERIOCIN PRODUCTION BY LACTIC ACID BACTERIA
Bibliographic record
Abstract
ABSTRACT A total of 300 strains of lactic acid bacteria (LAB) were screened for the production of bacteriocins active against Listeria innocua or Escherichia coli by using two different techniques: the conventional well‐diffusion assay and a newly developed one based on turbidity measurement of the growth of an indicator bacterium in the neutralized cell‐free supernatant of the putative bacteriocin‐producing strain. The latter technique, designated as the multiwell antagonistic activity assay (MW3A), offers advantages over the previously known methods. Notably, it allows testing simultaneously a large number of LAB for the production of bacteriocins against more than one indicator strain, while including appropriate controls for confirmation of the bacteriocinogenic nature of the inhibitory substances. Furthermore, five enterococcal strains were shown to produce bacteriocins active against the gram‐positive and gram‐negative indicator strains used in this study, suggesting that these enterococci or their bacteriocins have good potential to enhance food safety and keeping quality. PRACTICAL APPLICATIONS The present study describes a rapid and semiautomatic nephelometry method to screen for bacteriocin‐producing lactic acid bacteria (LAB). The method uses a microtiter plate where the inhibition of the growth of indicator strains in the presence of a bacteriocin is revealed by a decrease in OD as function of time. Concomitantly, this method determines the proteinaceous nature of the antimicrobial substance and its mode of action (i.e., bactericidal or bacteriostatic) while excluding the effect of interfering antimicrobials produced by LAB (e.g., hydrogen peroxide and organic acids). Furthermore, the newly described method differs from previously described ones by its ability to test for a relatively large number of putative bacteriocin‐producing strains using different controls and indicator strains, and allow early detection of bacteriocin‐producing strains (within 24 h). Another feature of this method is its ability to detect with confidence bacteriocins active against gram‐negative bacteria. These performances have potential to be used for rapid detection of LAB having strong capacity to inhibit pathogenic or spoilage bacteria by means of bacteriocins for possible applications in food preservation strategies.
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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 | 0.003 | 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".