Imperial College London/Notebook/11 September 2009

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
[[Media:Diauxic growth_11-09.xls| 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)