Imperial College London/Notebook/8 September 2009

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

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)