Critical shear stresses of <i>Pseudomonas aeruginosa</i> biofilms from dental unit waterlines studied using microfluidics and additional magnesium ions
Bibliographic record
Abstract
A microfluidic approach was used to study the effect of shear stress on biofilms from a dental unit waterline (DUWL)-isolated P. aeruginosa strain, PPF-1. During the application of relevant shear stress levels to DUWLs, the response of the PPF-1 biofilm was observed and compared to that of a well-studied clinical P. aeruginosa strain, PAO1. The response measurements were repeated for biofilms exposed to additional Mg2+ ions. Optical density maps were transformed into pseudo three-dimensional representations of the complex biofilm structures, and computational fluid dynamic simulations were used to determine the critical shear stresses for biofilm sloughing. In the absence of Mg2+, PPF-1 biofilms showed weaker attachment than PAO1 biofilms and highly intertwined slough/regrowth cycles occurring within the shear stress range of 1.42 ± 0.32 and 0.95 ± 0.27 Pa. This suggests that in a low ionic environment, the PPF-1 strain produces ejected biofilm material nearly continuously, which can result in increased downstream colonization of engineered flow systems. Introducing Mg2+ into the PPF-1 biofilm culture increased mechanical stability, which resulted in elevated tolerances to shear stresses up to a critical value of 5.43 ± 1.52 Pa, which was similar to the critical shear stress value of 4.23 ± 1.22 Pa for the PAO1 strain. Moreover, the enhanced Mg2+ concentrations seemed to place the PPF-1 biofilm into a viscoplastic mechanical state, which resulted in signature responses to critical shear stresses, such as catastrophic sloughing involving abrupt tearing that produced clean edges at the fracture boundary, indicating that the biofilm had become brittle.
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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 | 0.000 | 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) | 0.000 | 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".