This year, Team Fudan-CHINA is participating in the fifth iGEM interlab study to determine correlation between fluorescence protein expression, cell absorbance and cell density.
Materials:
-iGEM Measurement Kit
-test plasmids delivered in Part Distribution Kit Plates
-self-made competent E.coli DH5α strain
-Bio-Tek Cystation plate reader
-Commonly used laboratory consumables

Calibration #1 – OD600 reference
LUDOX sample was prepared according to the interlab protocol of which OD600 and Abs600 was read through plate reader to establish a transformation of absorbance raw data into OD600 measurements. Path length fixation was turned off during this and every following test.
Calibration #2 – Absorbance standard curve
Serial dilution of silica beads was prepared on a 96 well plate according to the interlab protocol and Abs600 of each well was tested. An absorbance curve was generated using those data collected which seemed to partly deviate from a strict linear relationship. This should result from pipetting errors.
Calibration#3 – fluorescence standard curve
Serial dilution of standard fluorescein was prepared according to the interlab protocol and fluorescence of each well was tested under the condition of 485nm excitation and 528nm emission. Measurement gain was tuned to 50 to keep readings under OVERFLOW and was maintained during following tests.
Cell measurement
Each test plasmid was transformed into E.coli DH5α and single colony obtained on the plate. 2 colonies was picked and cultivated in 5mL LB medium + Chl overnight. Samples of 0hr and 6hr of incubation was prepared according to interlab protocol. Please be noted that cultures were diluted to Abs600 0.02 in 12mL LB + Chl in the original 15mL tube where it was grown overnight instead of a new 50mL tube. Besides, Abs600 of overnight culture was read and dilution to 0.02 calculated according to equation provided in the interlab protocol but dilution results seemed to deviate from expected Abs600 of 0.02. Please refer to our submitted data for further information.
Colony Forming Units per 0.1 OD600
Cell cultures were grown and prepared according to the interlab protocol and spread on LB + Chl plates to determine CFU. Please be noted that due to lack of 2mL tube some dilutions of overnight culture were mixed in a 12 well plate and shaking was performed instead of vortexting tubes before pipetting. Besides, each culture was tested in 2 repeats instead of 3 due to shortage of appropriate Chl+ plates. Raw data were submitted in the questionnaire.

iGEM 2018 interlab measurement study page: https://2018.igem.org/Measurement/InterLab 2018 interlab plate reader protocol(pdf): https://static.igem.org/mediawiki/2018/0/09/2018_InterLab_Plate_Reader_Protocol.pdf