Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions
Bibliographic record
Abstract
Listeria monocytogenes strains are known to harbour plasmids that confer resistance to sanitizers, heavy metals, and antibiotics; however, very little research has been conducted into how plasmids may influence L. monocytogenes’ ability to tolerate food-related stresses. To investigate this, a library (n = 93) of L. monocytogenes plasmid sequences were compared. Plasmid sequences were divided into two groups (G1 and G2) based on a repA phylogeny. Twenty-six unique plasmid types were observed, with 13 belonging to each of the two repA-based groups. G1 plasmids were significantly (p < 0.05) smaller than G2 plasmids but contained a larger diversity of genes. The most prevalent G1 plasmid (57,083 bp) was observed in 26 strains from both Switzerland and Canada and a variety of serotypes. Quantitative PCR (qPCR) revealed a >2-fold induction of plasmid-contained genes encoding an NADH peroxidase, cadmium ATPase, multicopper oxidase, and a ClpL chaperone protein during growth under salt (6% NaCl) and acid conditions (pH 5) and ProW, an osmolyte transporter, under salt stress conditions. No differences in salt and acid tolerance were observed between plasmid-cured and wildtype strains. This work highlights the abundance of specific plasmid types among food-related L. monocytogenes strains, the unique characteristics of G1 and G2 plasmids, and the possible contributions of plasmids to L. monocytogenes tolerance to food-related stresses.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".