Reference no: EM132352557

In Lab 2 you generated a Bacterial Growth Curve and determined the Doubling Time for E. coli by plotting the Optical Density of the Growth Medium at different Timepoints. A more accurate -- and more useful -- Method would be to determine the Number of Viable Cells in the Growth Medium at different Timepoints.

You would inoculate a Flask containing 100 ml of Nutrient Broth in a Shaking Water Bath with 1000 μl of Exponential E. coli (1.0 x 1010 Cells/ml) at T= 0.

At each Timepoint, you take 500 μl from your Flask in the 37°C Shaking Water Bath and transfer it to a Tube containing 4.5 ml of Sterile Growth Medium (10-1 Dilution). You then transfer 500 μl from this 10-1 Dilution Tube to 4.5 ml of Sterile Medium in your 10-2 Tube. You continue this Dilution Process until you have made 10-1 through 10-8 Dilutions for each Timepoint. You then Spread Plate 100 μl from each of these Dilutions onto a Nutrient Agar Plate (Spread Plate Technique) and incubate these Plates at 37°C for 24 Hours.

The next Day, you count the Number of Colonies on the Plates you made at each Timepoint. You then do the necessary Calculations to determine the Number of Bacteria per Milliliter of Nutrient Broth in your 37°C Flask in the Shaking Water Bath.

Your Data are:

Timepoint Colonies

0 60

10 79

20 103

30 134

40 175

50 230

E. coli per ml

6.00 x 10^7

7.90 x 10^7

1.03 x 10^8

1.34 x 10^8

1.75 x 10^8

2.30 x 10^8

What was the Doubling Time for the E. coli in this Experiment?