Team:TecCEM/InterLab

Synthetic biology and all the engineering disciplines need to be reliable and repeatable, this year iGEM TecCEM 2018 is one of the teams that participated in the Fifth International InterLaboratory Measurement Study. In this page, we report the results obtained during all protocols.

Competent cell - transformation DH5-alpha

Transformations of all devices were performed, and the resulting transformant strains were plated on LB agar, with 35 μg/mL chloramphenicol. Two colonies per plate were separated into two independent cultures.

Verification

We verified the presence and size of the device plasmids in the transformant strains by running an agarose gel electrophoresis.

Table 1. Devices from the Interlab Study with their pait number and respective size.

Device Part Number Size (bp)
Negative Control BBa_R0040 2124
Positive Control BBa_I20270 2989
Device 1 BBa_J364000 2988
Device 2 BBa_J364001 2988
Device 3 BBa_J364002 2988
Device 4 BBa_J364007 2988
Device 5 BBa_J364008 2988
Device 6 BBa_J364009 2988

Calibration Protocol

The main objective of this calibration LUDOX protocol is to use LUDOX CL-X to get the conversion factor between absorbance (Abs600) from the plate reader and the OD600 measurement.

Table 2. OD600 Reference Point - LUDOX Protocol

LUDOX CL-X H2O
Replicate 1 0.059 0.033
Replicate 2 0.061 0.033
Replicate 3 0.062 0.033
Replicate 4 0.060 0.033
Arith. Mean 0.061 0.033
Corrected Abs600 0.028
Reference OD600 0.063
OD600/Abs600 2.291

Particle standard curve - Microsphere Protocol

The aim of this protocol is to establish a standard curve from a microsphere solution. These microspheres have similar size and optic properties to bacterial cells, therefore, they may be used to calibrate. After preparing the Microsphere Stock Solution, serial dilutions were made in a 96-well plate as instructed. To achieve reliable results, the plate reader was set to shake the samples just before reading them. The reads were registered in the given Excel file and are shown below.

Fluorescence standard curve - Fluorescein Protocol

Following the protocol for the fluorescence standard curve using fluorescein, we prepared the corresponding reactants and the requested serial solutions in the 96-well plate.

Cell measurement Protocol

Table 3. Absorbance and fluorescence at hour 0 and hour 6.

Hour 0 Hour 0 Hour 6 Hour 6
Abs600 Raw Readings Fluorescence Raw Readings Abs600 Raw Readings Fluorescence Raw Readings
Negative Control 0.078375 153.5 0.46225 170.125
Positive Control 0.074 220.125 0.428125 1926.75
Device 1 0.0715 439.125 0.241 4319.5
Device 2 0.079125 266.625 0.442375 2148.5
Device 3 0.075625 151.125 0.430375 207.625
Device 4 0.074375 601.5 0.347625 5545.875
Device 5 0.075625 335.875 0.16425 2039
Device 6 0.077 227.125 0.45325 1151
LB + Chlor (Blank) 0.053375 158.625 0.051125 177.5

After performing all three calibration measurements, we proceeded to execute the cell measurement protocol, previously having the overnight cell culture of each device and control. We use the same plate and volume that we used in the calibration protocol, also the same settings in order to make valid the measurement. We defined the difference between the measurement of the absorbance and fluorescence, starting in the hour 0 until the hour 6.