Anti-<i>Escherichia coli</i>O157:H7 activity of free fatty acids under varying pH
Bibliographic record
Abstract
Following screening of 4 strains of Escherichia coli O157:H7 (E32511, E318N, H4420N, and R508N) for acid tolerance, strain H4420N was selected for further study into the influence of pH on bactericidal activity of 6 fatty acids (capric, lauric, palmitic, oleic, linoleic, and linolenic). Strain H4420N was cultured for 6 h in Luria-Bertani broth amended with individual fatty acids at 20 mmol/L, with pH adjusted to 7.0, 4.3, or 2.5. None of the fatty acids exhibited bactericidal activity at pH 7.0 (p >0.05). At pH 4.3, only capric, lauric, and linoleic acids reduced viability of H4420N (p < 0.05). At pH 2.5, oleic (C18:1) and linolenic (C18:3) acids had modest effects on H4420N viability, whereas capric (C10:0), lauric (C12:0), and linoleic (C18:2) acids resulted in a reduction > or =5 log10 colony-forming units (CFU)/mL (p < 0.05). Capric and lauric acids were examined further at pH 2.5 over a range of concentrations (0.15-20 mmol/L). After 10 min of exposure, 5 log10 CFU/mL reductions (p < 0.05) were achieved by lauric acid at 2.5 mmol/L and by capric acid at 0.31 mmol/L. Acid stress increased the sensitivity of acid-tolerant E. coli O157:H7 strain H4420N to fatty acids. Including sources of these fatty acids in diets for cattle might impair the ability of this zoonotic pathogen to survive passage through the stomach, possibly reducing the potential for its colonization in the lower gut.
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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) | 0.001 | 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".