Bibliographic record
Abstract
Conjugation of plasmids is widespread among bacteria and contributes to the spread of antibiotic resistance. In the natural environment, microorganisms predominantly exist in the form of biofilms or other bioaggregates, where they may be exposed to contaminants such as antibiotics, at subinhibitory concentrations. Bacterial cells in older biofilms have lower growth activity due to oxygen and nutrient limitation in the deeper layers of the biofilms. In batch culture, population growth eventually ceases during the stationary phase. Thus, the steady state of biofilms may resemble stationary growth phase cultures. Our objectives were to study (i) the effect of cell growth phases and (ii) subinhibitory and minimum inhibitory concentrations (MIC) of antibiotics on transconjugant formation in both batch cultures and biofilms. Additionally, (iii) the effect of variable nutrient concentrations on MIC was investigated and (iv) an optimization of RT-PCR method for the detection of traA gene (which encodes pilus biosynthesis) expression was carried out. To study the effect of cell growth phases on transconjugant formation, plate matings were carried out utilizing planktonic cultures grown to exponential or stationary phase of donor and recipient strains. The results showed that transconjugant abundance was the highest (20± 0.08%) when both plasmid donor and recipient cells were grown to the stationary phase. However, the growth phase of the donor did not seem to play a role in biofilms. When donor cells were harvested from either the exponential or stationary phase of growth, and inoculated into 24 h old recipient biofilms, there was no statistically significant difference between transconjugant abundance. A higher percentage of transconjugants was detected in plate matings when the donor was exposed to 0.5× minimum inhibitory concentration of gentamicin and additionally challenged with gentamicin at MIC. In biofilms, transconjugant formation was not enhanced when the donor cells were grown with 0.5× MIC gentamicin, and 0.5× MIC gentamicin was added to the biofilms. A decrease in nutrient concentration was associated with a decrease in the MIC. traA expression, detected using RT-PCR in plasmid donor cells grown to early exponential and late exponential phases did not coincide with an increase in transconjugants.
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".