IGEM:IMPERIAL/2007/Projects/Biofilm Detector/Notes
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Infector Detector: Notes
Making Biofilm
- Freshly-grown growth-phase E. coli ZK1056 culture is added to sterile medium to a concentration of 5 × 107 cells/mL.
- Round 15 mm sterile glass coverslips are placed upright in the wells of a 24-well plate with sterile plastic stands
- Add 1 mL of E. coli solution to each well.
- The 24-well plate is immediately covered and transferred to a 30 °C incubator.
AHL produced in biofilms:
(Notes on the journal modeling AHL production in biofilms of the same bacterial population)
AHL synthesis is subject to autoinduction in which production of AHLs operates
as a positive feedback loop.
Assumptions made in the model:
- All bacterial cells are physiologically identical with regard to size, shape and permeability of the cell membrane, as well as production and degradation rates of the signalling molecules
- Bacterial population exhibit a standard logistic growth pattern
- No metabolic or physiological lag is assumed
- At very low Cbc, the net rate of AHL production, h(Cbc), is assumed to be determined solely by the difference between basal production, Bp, and degradation of AHLs
- Degradation of AHLs is proportional to the concentration of AHL and occurs at a rate d*Cbc
Not considered in the model: permeability constant a, which is characteristic of the bacterial cell membrane, the diffusability of a given AHL, and the viscosity of the cell and the biofilm
Conclusions from the model: high concentrations of AHL inside cells could be achieved at very low population densities. Rapid rise in AHL concentration early in population growth, followed by a plateau, followed by another rise to a second plateau
