Imperial College London/Notebook/8 September 2009

From 2009.igem.org

Contents

Testing

Diauxic growth 8th Sep

Protocol considerations

  • Using spectrophotometer at 600nm
  • Blanks are all the relevant carbon sources, but subsequently realised that all blanks were roughly the same (within 0.03)
    • Therefore, subsequent readings= blank + 6 sample
  • Overnight culture had OD of 1.64.
    • 800ul was put into each sample of 40ml~ 0.033 OD
    • ie same initial OD
  • Grown in 6 separate 50ml falcon tubes and shaking in incubator at 28 degrees Celsius
  • 1ml taken out at 1 hr intervals from the falcon tube and placed into spectrophotometer

Results

Diauxic growth.jpg
Download raw data

Conclusions

  • Glucose, as expected, had the highest growth rate
  • Cells under all secondary carbon source conditions appear to stop growth at 6 hrs.
    • Therefore, we can suggest that the switch point is after 6 hours
    • However, further data at longer time points are required to confirm this.

Suggestions/Improvements

  • Longer duration of taking readings (but currently limited to 8hrs- length of a day and multiplate reader evaporation)
  • Earlier switch point can be induced by adding a smaller concentration of glucose to media
    • suggested 0.01% Glucose for next experiment (we predict it will take around 2 hours)

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