• As a software team, we are proud to participate in interlab study and do some contribution to iGEM and synthetic biology community.

  • This year, interlab study aims to not only collect common and comparable data from teams all over the world but also see how close the

  • numbers worldwide can be.

  • Following the standard protocol given by headquarter, we measured GFP fluorescence and OD600 in Escherichia coli strain DH5α.

  • Below, we detail our Interlab Study experience and discuss what our findings could mean.

  • We transformed Escherichia coli DH5α with Device 1, 2, 3, positive control and negative control. Then we

  • inoculated them on LB plate which containing chloramphenicol. Then, we picked single colonies, afterwards,

  • moved them into liquid cultures (LB medium). After an overnight cultivation, liquid cultures were diluted

  • with LB medium until the value of OD600 reached 0.02. Then we took out 100 μL samples from the cultures

  • every hour (until 6 hours). At last, we measured OD600 and fluorescence of all samples.

  • The bacteria were cultivated in Lysogeny

  • Broth(LB) plate with chloramphenicol added

  • when doing transformation. The plates were

  • kept at 37°C. Colonies we picked were

  • grown in 5ml LB medium with chlorampheni-

  • col. Afterwards, they were kept at 37°C and

  • 220 rpm shaking frequency. We used 50ml

  • falcon tubes with 10ml LB medium and chlor-

  • amphenicol to target OD600 of 0.02.

Strains & Devices Transformed
  • We used Escherichia coli strain DH5α cells for t-

  • ransformation. Three devices and two controls are

  • all provided by iGEM HQ as follows:

  • Test Device 1: J23101.B0034.E0040.B0015 in pSB1C3

  • Test Device 2: J23106.B0034.E0040.B0015 in pSB1C3

  • Test Device 3: J23117.B0034.E0040.B0015 in pSB1C3

Generating FITC Fluorescence Standard
Curve by Using Plate Reader
  • We have used 96-well plates to do the plate reader’s measurement.

  • A serial dilution was performed to generate a FITC fluore-

  • scencestandard curve. When measuring fluorescence,the excitation

  • wavelength we set was 480nm and emission wavelength was 520nm.

Using LUDOX-S30 as
    A Single Point Reference
  • We used LUDOX-30 to transform our absorb-

  • ance data into standard OD600 measurement.

  • Volumes of LUDOX was 100μl. We prepared a

  • column of 4 wells containing 100 μl LUDOX

  • and 4 wells containing water. The samples

  • were measured using plate reader.

Measuring Fluorescence &
OD600 by Using Plate Reader
  • Colonies with devices tested by us were picked from the plates, then were cul-

  • tured overnight in 5ml LB medium with chloramphenicol. The liquid cultures

  • were diluted to target OD600=0.02. The fluorescence and OD600 of samples

  • at 0,1,2,3,4,5, and 6 hours were measured by using 96-well plate. The volumes

  • of samples were 100 μl. LB medium with chloramphenicol were used as blank.



  • Generally, the first hour maybe lag phase, during this time bacteria reproduced rarely. In the next 4 hours, roughly,

  • the value of AU increases exponentially in speed, which indicates the bacterium may in the logarithmic phase. The

  • growth rate ranks from high to low is device3, device2, device1, negative control and positive control. In fifth to

  • sixth hours, because of the limitation of nutrients, it turned to the stationary phase. Exceptionally, a replicatation

  • of device 3 increased so rapidly that it entered the decline phase on about the sixth hour.

Fig.1 Abs600 curve


We've done the whole experiment twice, and we get a little different result.

Fig.2 Standard curve for fluorescence intensity

  • At first time, result shows that, as time went by, the fluorescence value of device 2,device 1 and device 3

  • decreases one by one. Fluorescence value for device 2 is highest at every check point while device 3 is

  • lowest. Fluorescence value for device 1 is obviously higher than device 3 and negative control.

  • Fluorescence value for device 3 is close to negative control.

Fig.3 Fluorescence curve (the 1st time)

Fig.4 Fluorescence value (the 1st time)

  • At the second time, results of device 2 and 3 are in agreement to the first time, however, fluorescence

  • value for device 1 is pretty different, which going close with device 3 and negative control. It means that

  • device 1 strain didn’t express GFP. But device 1 contains GFP gene and it was able to express.

Fig.5 Fluorescence curve (the 2nd time)

Fig.6 Fluorescence value (the 2nd time)

Fig.7 Fluorescence/Abs600 curve