5 September 2008

Wetlab

Colony Counting

After re-calibrating our illuminator, it can now count colonies with a fair degree of accuracy. Manual addition and removal of points allows us to fine-tune the results, so we will use this method from now on.

Trial Run: B. subtilis Growth Curve

In our second trial run to obtain growth and calibration curves for B. subtilis, we cultured our "B. subtilis" for two days and continously monitored the changes in OD600. By plotting OD600 against Time/h, we obtained the following growth curve for "B. subtilis".

Growth Curve for B. subtilis

Calibration Curve

For six of the data points from the above growth curve, we plated 0.1 ml of B. subtilis on LB agar plates and performed serial dilution in order to obtain the colony-forming units (CFU per ml) for the corresponding OD600. However, we only managed to obtain two sets of valid data. The B. subtilis mixtures we plated for higher values of OD600 were too dilute, hence no bacterial growth were observed on these LB agar plates.

Growth Curve for B. subtilis

Suggestions for Further Improvements

Pipette tips should be changed...