Acid tolerance response of biofilm cells of<i>Streptococcus mutans</i>
Bibliographic record
Abstract
Streptococcus mutans, a major etiological agent of dental caries, is a component of the dental plaque biofilm and functions during caries progression in acidic lesions that may be at or below pH 4. In this study, we were interested in determining the acid tolerance of 1-7-day chemostat-grown biofilm cells of S. mutans BM71 growing in a semi-defined medium at a rate consistent with that of cells in dental plaque (dilution rate=0.1 h(-1)), as well as, assessing the capacity of 2- and 5-day biofilms to induce an acid tolerance response that would enhance survival at a killing pH (3.5). As expected, biofilm cell growth increased (2.5-fold) from day 1 to day 7 (10.6-25.7 x 10(6) cells cm(-)(2)) with the percentage live cells over that period averaging 79.4%, slightly higher than that of planktonic cells (77.4%). Biofilms were highly resistant to acid killing at pH 3.5 for 2 h with survival ranging from 41.8 (1 day) to 63.9% (7 day), while the percentage of live cells averaged 43.4%. Planktonic and dispersed biofilm cells were very acid-sensitive with only 0.0009%- and 0.0002-0.2% survivors, respectively. Unlike the planktonic cells, the incubation of 2- and 5-day biofilms at pH 5.5 for periods of up to 6 h induced strong acid tolerance responses that enhanced survival during a subsequent exposure to acid killing at pH 3.5.
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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 | 0.000 | 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".