Interlab

We went to University of Washington Tacoma to use the FilterMax F5 Multi-Mode Microplate Reader. So we would like to say thank you to Dr. Finke for letting us to use his equipment!

The purpose of this year’s interlab protocol was to take the absorbance of the bacterial stain E. Coli (created by transforming the plasmid) and standardize the fluorescence rate for future use at iGEM. Our next week of interlab lab work was split into two days: calibration day and cell measurement protocol day. The team quickly learned the importance of accurate pipetting as we had our first experiences with the plate reader.

We followed all the protocols provided by iGem, so click hereto see the methods and materials we used.

Results:

After overnight incubation, we put out the samples and counted the one that had less than 300 colonies. After counting the samples, we multiplied with the dilution factor given in interlab to calculate CFU/mL. We had 6 samples each for positive and negative controls, and it was categorized by dilution 3, 4, and 5, and each sample had a different dilution factor according to the protocol. We noticed that there were a samples , so some of the data had to be left blank. CFU stands for colony forming unit, so the number recorded as CFU/mL shows the number of colonies present for every 1 mL of sample (similar as concept of molarity). And the concentration of bacteria is directly related to the fluorescence. If there is more concentration, it will fluorescence more. The measuring of absorbance also helped us to see the concentration, since high concentration of bacteria will scatter the light more than the diluted samples, resulting in the high absorbance value.