InterLab Study

As a team, we took part in iGEM’s Fifth International Interlaboratory Study in synthetic biology. Difficulty in taking reliable and reproducible measurements remains a key obstacle in the field of synthetic biology, especially for fluorescence data. Data from different groups usually cannot be compared because they are reported in different units or processed in different ways. The goal of the iGEM InterLab Study is to identify and correct the sources of systematic variability in synthetic biology measurements.

For the fifth installment of the InterLab, iGEM wants to answer the following question: Can we reduce lab-to-lab variability in fluorescence measurements by normalizing to absolute cell count or colony-forming units (CFUs) instead of OD? The parts used include six test devices (BBa_J364000, BBa_J364001, BBa_J364002, BBa_J364003, BBa_J364004, BBa_J364005), as well as a positive (BBa_I20270) and negative (BBa_R0040) control. All parts are located in the pSB1C3 plasmid and carry chloramphenicol resistance.

Our involvement in the study required that we submit measurement data dealing with the fluorescence of GFP and OD associated with cells transformed with different test devices. Throughout our experiments, we tested 8 plasmids (2 controls and 6 test devices), and we measured the absorbance and fluorescence of our samples using a Tecan Infinite m1000 pro plate reader. We broke the given procedure into four main components: (1) transforming the two controls and 6 test devices into competent DH5α cells, (2) measuring the OD600 reference point of LUDOX CL-X, (3) graphing a particle standard curve for monodisperse silica microspheres and a Fluorescein standard curve (4) measuring the GFP fluorescence and absorbance of samples of previously transformed DH5α cells taken over 2 hour intervals and 5) counting colony forming units (CFUs) per 0.1 OD600 E. coli cultures.

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