Team:WHU-China/InterLab

Interlab Study

      It is a good opportunity for our team to participate in the project which aims to improve the measurement tools available to both the iGEM community and the synthetic biology community as a whole. And we are glad to cooperate with many other teams from around the world to solve the same problem in synthetic biology. This year's iGEM InterLab study is about could we use CFU/ml to replace the absorbance in fluorescence/od measurement.

To accomplish the goals, we use measure the fluorescence and absorbance with SpectraMax i3x plate reader. In additionally we need to get the competent DH5α and transforme the plasmids into cells. And this wiki will present the workflow and the results we get. We separate the wiki into 3 segments , and the first part is transformation of the plasmids into DH5α.

Transformation

According to the requirements of iGEM, we transformed all the parts (BBa_R0040, BBa_I20270, BBa_J364000, BBa_J364001, BBa_J364002, BBa_J364007, BBa_J364008, BBa_J364009) into competent DH5α. And we successfully get sufficient colonies in all the plates. Therefore we select 2 colonies in each plate to cultivate them In LB medium containing chloramphenicol for overnight with 37, 220rpm.

Calibration 1: OD600 Reference point - LUDOX

   Through this calibration, we could transform the absorbance (Abs600 ) data from plate reader into a comparable OD 600 measurement in the spectrophotometer, which will help a lot during the following experiments. By doing so, we get the data following.

Table 1: We get the ratiometric conversion factor of 3.549 in our plate reader after measuring the wells adding 100ul Ludox and water.

LUDOX CL-X

H2O

Replicate 1

0.056

0.039

Replicate 2

0.059

0.039

Replicate 3

0.058

0.040

Replicate 4

0.056

0.040

Arith. Mean

0.057

0.040

Corrected Abs600

0.018

Reference OD600

0.063

OD600/Abs600

3.549

Calibration 2: Particle Standard Curve - Microsphere

Because the monodisperse silica microspheres are similar to the cells in size and optical characteristics during measuring the absorbance in 600nm. It is necessary to construct the particle standard curve and in this way we could change the absorbance into estimated cells.

Table 2 :the raw data we get after diluting a series of monodisperse silica microspheres in the 96 cell well plates.

Number of Particles

2.35E+08

1.18E+08

5.88E+07

2.94E+07

1.47E+07

7.35E+06

3.68E+06

1.84E+06

9.19E+05

4.60E+05

2.30E+05

0

Replicate 1

0.542

0.347

0.202

0.124

0.080

0.059

0.050

0.047

0.043

0.041

0.040

0.042

Replicate 2

0.531

0.344

0.187

0.116

0.077

0.057

0.048

0.042

0.041

0.041

0.040

0.038

Replicate 3

0.794

0.319

0.177

0.105

0.076

0.062

0.049

0.046

0.043

0.042

0.040

0.039

Replicate 4

0.609

0.314

0.193

0.106

0.076

0.057

0.048

0.046

0.043

0.042

0.040

0.042

Arith. Mean

0.619

0.331

0.190

0.113

0.077

0.059

0.049

0.045

0.043

0.042

0.040

0.040

Arith. Std.Dev.

0.122

0.017

0.011

0.009

0.002

0.002

0.001

0.002

0.001

0.001

0.000

0.002

Arith. Net Mean

0.579

0.291

0.150

0.073

0.037

0.019

0.009

0.005

0.002

0.001

0.000

Figure 1:The Particle Standard Curve with monodisperse silica microspheres (log scale)

Figure 2 : The Particle Standard Curve with monodisperse silica microspheres (line scale)

 

Table 3: The raw data after measuring the fluorescence (excitation light: 485 nm, emission light 530nm) in plate reader.

Fluorescein uM

10.00

5

2.5

1.25

0.625

0.313

0.156

0.078

0.039

0.0195

0.0098

0

Replicate 1

4.833E+04

2.670E+04

2.013E+04

1.019E+04

4.769E+03

2.687E+03

1.385E+03

6.670E+02

3.450E+02

1.630E+02

6.800E+01

2.000E+00

Replicate 2

4.477E+04

3.233E+04

1.903E+04

1.032E+04

4.521E+03

2.770E+03

1.147E+03

5.660E+02

2.560E+02

1.950E+02

1.200E+02

4.000E+00

Replicate 3

4.932E+04

3.348E+04

2.032E+04

1.298E+04

6.118E+03

2.550E+03

1.468E+03

5.660E+02

2.710E+02

1.730E+02

7.900E+01

5.000E+00

Replicate 4

4.846E+04

3.634E+04

2.116E+04

1.180E+04

4.451E+03

3.568E+03

1.445E+03

7.330E+02

3.010E+02

1.310E+02

6.800E+01

8.000E+00

Arith. Mean

4.772E+04

3.221E+04

2.016E+04

1.132E+04

4.965E+03

2.894E+03

1.361E+03

6.330E+02

2.933E+02

1.655E+02

8.375E+01

4.750E+00

Arith. Std.Dev.

2.012E+03

4.042E+03

8.766E+02

1.323E+03

7.808E+02

4.586E+02

1.471E+02

8.192E+01

3.925E+01

2.660E+01

2.472E+01

2.500E+00

Arith. Net Mean

4.771E+04

3.221E+04

2.016E+04

1.132E+04

4.960E+03

2.889E+03

1.357E+03

6.283E+02

2.885E+02

1.608E+02

7.900E+01

 

Figure 3 : The fluorescein standard curve in log scale (excitation light:485nm, emission light 530nm)

Figure 4 : The fluorescein standard curve in line scale (excitation light:485nm, emission light 530nm)

 

The standard curve are straight line in both the line and log scale. So the standard curve may be credible after we use it in following experiment and the analyzing results.

Cell measurement

The fourth segment is the results of absorbance 600nm and fluorescence of transformed cells. According to the protocol we get the data and comparing them with the results in CFU/ml to get our conclusion whether CFU/ml could replace the absorbance in fluorescence/od in laboratory works.

Table 4: The raw data we get from the plate reader after measuring the samples from 0h and 6h during cultivation of the transformed cells.

Fluorescence Raw Readings:

Hour 0:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

LB + Chlor (blank)

Colony 1, Replicate 1

126

108

128

197

180

293

169

119

64

Colony 1, Replicate 2

93

104

72

250

136

264

151

164

66

Colony 1, Replicate 3

100

112

123

233

122

276

135

157

70

Colony 1, Replicate 4

98

129

135

189

78

258

98

148

68

Colony 2, Replicate 1

87

130

138

176

161

223

134

163

79

Colony 2, Replicate 2

112

131

125

156

244

161

142

159

66

Colony 2, Replicate 3

103

125

89

132

159

255

160

158

64

Colony 2, Replicate 4

89

139

105

143

134

245

148

163

66

 

Hour 6:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

LB + Chlor (blank)

Colony 1, Replicate 1

10203

18662

17149

18644

10574

22936

20801

13347

7858

Colony 1, Replicate 2

11003

19975

18619

19508

11235

23844

19238

13822

8292

Colony 1, Replicate 3

11132

20487

18620

19861

11685

24304

19073

14437

8165

Colony 1, Replicate 4

11888

21333

18801

20514

11712

29351

19624

14765

8494

Colony 2, Replicate 1

11077

17324

20389

18729

10855

25237

20372

15074

8274

Colony 2, Replicate 2

10855

18456

20509

18580

11291

25137

20489

15131

8684

Colony 2, Replicate 3

10900

18443

21305

19037

11065

24776

20467

15603

8563

Colony 2, Replicate 4

10386

18345

24383

18403

10966

25233

19799

15265

8544

 

Abs600 Raw Readings:

Hour 0:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

LB + Chlor (blank)

Colony 1, Replicate 1

0.05

0.053

0.049

0.05

0.062

0.048

0.045

0.054

0.041

Colony 1, Replicate 2

0.049

0.05

0.048

0.052

0.052

0.046

0.044

0.048

0.04

Colony 1, Replicate 3

0.049

0.055

0.051

0.055

0.058

0.046

0.046

0.053

0.042

Colony 1, Replicate 4

0.043

0.047

0.052

0.049

0.054

0.049

0.045

0.051

0.044

Colony 2, Replicate 1

0.048

0.052

0.056

0.052

0.051

0.047

0.043

0.049

0.041

Colony 2, Replicate 2

0.054

0.058

0.052

0.049

0.05

0.051

0.046

0.052

0.043

Colony 2, Replicate 3

0.052

0.049

0.054

0.051

0.053

0.049

0.048

0.05

0.042

Colony 2, Replicate 4

0.051

0.047

0.047

0.051

0.051

0.048

0.05

0.054

0.041

 

Hour 6:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

LB + Chlor (blank)

Colony 1, Replicate 1

0.313

0.224

0.22

0.239

0.271

0.229

0.214

0.24

0.043

Colony 1, Replicate 2

0.328

0.226

0.221

0.254

0.266

0.228

0.218

0.244

0.049

Colony 1, Replicate 3

0.294

0.218

0.217

0.25

0.264

0.234

0.216

0.252

0.043

Colony 1, Replicate 4

0.276

0.227

0.223

0.233

0.275

0.225

0.216

0.25

0.042

Colony 2, Replicate 1

0.279

0.236

0.238

0.264

0.249

0.255

0.206

0.205

0.044

Colony 2, Replicate 2

0.266

0.237

0.228

0.277

0.248

0.255

0.208

0.21

0.041

Colony 2, Replicate 3

0.27

0.236

0.236

0.264

0.241

0.252

0.202

0.202

0.05

Colony 2, Replicate 4

0.28

0.25

0.23

0.266

0.248

0.256

0.203

0.203

0.043

 

After synthesis the raw data that we get from the calibration protocol and cell measurement protocol, there are also some forms after analyzing. (for easily to compare the difference between the devices, there are some diagrams only present after cultivating 6h, because we think some data getting from samples in 0h is less valuable )

Table 5: The unit scaling factors of our standard curve in calibration experiment.


Unit Scaling Factors:

OD600 / Abs600

3.55

uM Fluorescein / a.u.

1.25E-04

Table 6: The net absorbance 600nm

 

Net Abs 600

Hour 0:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

0.009

0.012

0.008

0.009

0.021

0.007

0.004

0.013

Colony 1, Replicate 2

0.009

0.010

0.008

0.012

0.012

0.006

0.004

0.008

Colony 1, Replicate 3

0.007

0.013

0.009

0.013

0.016

0.004

0.004

0.011

Colony 1, Replicate 4

-0.001

0.003

0.008

0.005

0.010

0.005

0.001

0.007

Colony 2, Replicate 1

0.007

0.011

0.015

0.011

0.010

0.006

0.002

0.008

Colony 2, Replicate 2

0.011

0.015

0.009

0.006

0.007

0.008

0.003

0.009

Colony 2, Replicate 3

0.010

0.007

0.012

0.009

0.011

0.007

0.006

0.008

Colony 2, Replicate 4

0.010

0.006

0.006

0.010

0.010

0.007

0.009

0.013

 

Hour 6:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

0.270

0.181

0.177

0.196

0.228

0.186

0.171

0.197

Colony 1, Replicate 2

0.279

0.177

0.172

0.205

0.217

0.179

0.169

0.195

Colony 1, Replicate 3

0.251

0.175

0.174

0.207

0.221

0.191

0.173

0.209

Colony 1, Replicate 4

0.234

0.185

0.181

0.191

0.233

0.183

0.174

0.208

Colony 2, Replicate 1

0.235

0.192

0.194

0.220

0.205

0.211

0.162

0.161

Colony 2, Replicate 2

0.225

0.196

0.187

0.236

0.207

0.214

0.167

0.169

Colony 2, Replicate 3

0.220

0.186

0.186

0.214

0.191

0.202

0.152

0.152

Colony 2, Replicate 4

0.237

0.207

0.187

0.223

0.205

0.213

0.160

0.160

Figure 5 : The net absorbance in 600nm of transformed cells after 6h cultivation

 

Table 7: The net Fluorescence data


Net Fluorescein a.u.

Hour 0:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

62.00

44.00

64.00

133.00

116.00

229.00

105.00

55.00

Colony 1, Replicate 2

27.00

38.00

6.00

184.00

70.00

198.00

85.00

98.00

Colony 1, Replicate 3

30.00

42.00

53.00

163.00

52.00

206.00

65.00

87.00

Colony 1, Replicate 4

30.00

61.00

67.00

121.00

10.00

190.00

30.00

80.00

Colony 2, Replicate 1

8.00

51.00

59.00

97.00

82.00

144.00

55.00

84.00

Colony 2, Replicate 2

46.00

65.00

59.00

90.00

178.00

95.00

76.00

93.00

Colony 2, Replicate 3

39.00

61.00

25.00

68.00

95.00

191.00

96.00

94.00

Colony 2, Replicate 4

23.00

73.00

39.00

77.00

68.00

179.00

82.00

97.00

 

Hour 6:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

2345.00

10804.00

9291.00

10786.00

2716.00

15078.00

12943.00

5489.00

Colony 1, Replicate 2

2711.00

11683.00

10327.00

11216.00

2943.00

15552.00

10946.00

5530.00

Colony 1, Replicate 3

2967.00

12322.00

10455.00

11696.00

3520.00

16139.00

10908.00

6272.00

Colony 1, Replicate 4

3394.00

12839.00

10307.00

12020.00

3218.00

20857.00

11130.00

6271.00

Colony 2, Replicate 1

2803.00

9050.00

12115.00

10455.00

2581.00

16963.00

12098.00

6800.00

Colony 2, Replicate 2

2171.00

9772.00

11825.00

9896.00

2607.00

16453.00

11805.00

6447.00

Colony 2, Replicate 3

2337.00

9880.00

12742.00

10474.00

2502.00

16213.00

11904.00

7040.00

Colony 2, Replicate 4

1842.00

9801.00

15839.00

9859.00

2422.00

16689.00

11255.00

6721.00

 

Figure 6 : The net fluorescein of transformed cells after 6h cultivation (excitation light:485nm, emission light 530nm)

Table 8: The um fluorescence/OD data


uM Fluorescein / OD

Hour 0:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

0.242

0.129

0.281

0.520

0.194

1.150

0.923

0.149

Colony 1, Replicate 2

0.105

0.134

0.026

0.539

0.205

1.160

0.747

0.431

Colony 1, Replicate 3

0.151

0.114

0.207

0.441

0.114

1.811

0.571

0.278

Colony 1, Replicate 4

-1.055

0.715

0.294

0.851

0.035

1.336

1.055

0.402

Colony 2, Replicate 1

0.040

0.163

0.138

0.310

0.288

0.844

0.967

0.369

Colony 2, Replicate 2

0.147

0.152

0.230

0.527

0.894

0.417

0.891

0.363

Colony 2, Replicate 3

0.137

0.306

0.073

0.266

0.304

0.959

0.562

0.413

Colony 2, Replicate 4

0.081

0.428

0.229

0.271

0.239

0.899

0.320

0.262

 

Figure 7 : The ratio of fluorescein/OD in 0h (excitation light:485nm, emission light 530nm)

Figure 8 : The ratio of fluorescein/OD after cultivation for 6h (excitation light:485nm, emission light 530nm)

 

Discussion: According to the net fluorescence per od value, the order of the strengths of the different  promoters is estimated based on the average of two colonies in each group. The conclusion is that "device 4">"device 5">"device1" approximately equal to "positive control" >"device 2">"device 6">"device 3">"negative control". The results of the comparison with the official RFP were basically the same, while the positive and negative controls and the repetition of the two colonies indicated that the results were credible.

Table 9 : The unit scaling factors of our standard curve in calibration experiment.


Unit Scaling Factors:

Hour 6:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

0.305

2.098

1.845

1.935

0.419

2.850

2.661

0.980

Colony 1, Replicate 2

0.342

2.320

2.111

1.923

0.477

3.054

2.277

0.997

Colony 1, Replicate 3

0.416

2.475

2.112

1.986

0.560

2.971

2.217

1.055

Colony 1, Replicate 4

0.510

2.440

2.002

2.212

0.486

4.007

2.249

1.060

Colony 2, Replicate 1

0.419

1.657

2.195

1.671

0.443

2.826

2.625

1.485

Colony 2, Replicate 2

0.339

1.753

2.223

1.474

0.443

2.703

2.485

1.341

Colony 2, Replicate 3

0.373

1.867

2.408

1.721

0.461

2.822

2.753

1.628

Colony 2, Replicate 4

0.273

1.665

2.978

1.554

0.415

2.755

2.473

1.477

Particles / Abs600

4.00E+08

MEFL / a.u.

7.51E+08

Table 10: MEFL/particle


MEFL / particle

Hour 0:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

1.29E+04

6.89E+03

1.50E+04

2.78E+04

1.04E+04

6.15E+04

4.93E+04

7.95E+03

Colony 1, Replicate 2

5.64E+03

7.14E+03

1.41E+03

2.88E+04

1.10E+04

6.20E+04

3.99E+04

2.30E+04

Colony 1, Replicate 3

8.06E+03

6.07E+03

1.11E+04

2.36E+04

6.11E+03

9.68E+04

3.05E+04

1.49E+04

Colony 1, Replicate 4

-5.64E+04

3.82E+04

1.57E+04

4.55E+04

1.88E+03

7.14E+04

5.64E+04

2.15E+04

Colony 2, Replicate 1

2.15E+03

8.72E+03

7.39E+03

1.66E+04

1.54E+04

4.51E+04

5.17E+04

1.97E+04

Colony 2, Replicate 2

7.86E+03

8.15E+03

1.23E+04

2.82E+04

4.78E+04

2.23E+04

4.76E+04

1.94E+04

Colony 2, Replicate 3

7.33E+03

1.64E+04

3.92E+03

1.42E+04

1.62E+04

5.13E+04

3.01E+04

2.21E+04

Colony 2, Replicate 4

4.32E+03

2.29E+04

1.22E+04

1.45E+04

1.28E+04

4.81E+04

1.71E+04

1.40E+04

 

Hour 6:

Neg. Control

Pos. Control

Device 1

Device 2

Device 3

Device 4

Device 5

Device 6

Colony 1, Replicate 1

1.63E+04

1.12E+05

9.87E+04

1.03E+05

2.24E+04

1.52E+05

1.42E+05

5.24E+04

Colony 1, Replicate 2

1.83E+04

1.24E+05

1.13E+05

1.03E+05

2.55E+04

1.63E+05

1.22E+05

5.33E+04

Colony 1, Replicate 3

2.22E+04

1.32E+05

1.13E+05

1.06E+05

2.99E+04

1.59E+05

1.19E+05

5.64E+04

Colony 1, Replicate 4

2.73E+04

1.30E+05

1.07E+05

1.18E+05

2.60E+04

2.14E+05

1.20E+05

5.67E+04

Colony 2, Replicate 1

2.24E+04

8.86E+04

1.17E+05

8.93E+04

2.37E+04

1.51E+05

1.40E+05

7.94E+04

Colony 2, Replicate 2

1.81E+04

9.37E+04

1.19E+05

7.88E+04

2.37E+04

1.45E+05

1.33E+05

7.17E+04

Colony 2, Replicate 3

2.00E+04

9.99E+04

1.29E+05

9.20E+04

2.46E+04

1.51E+05

1.47E+05

8.71E+04

Colony 2, Replicate 4

1.46E+04

8.90E+04

1.59E+05

8.31E+04

2.22E+04

1.47E+05

1.32E+05

7.90E+04

Figure 9 : The ratio of fluorescein/particle in 0h (excitation light:485nm, emission light 530nm)

Figure 10 : The ratio of fluorescein/particle after cultivation for 6h (excitation light:485nm, emission light 530nm)

 

Discussion : MEFL/particle also show the same results that device 4 have the stongest promotor and device 3 have the weakest promotor. And the decreasing promotor strength is  "device 4">"device 5">"device1" approximately equal to "positive control" >"device 2">"device 6">"device 3">"negative control", which corresopnd to the results in flourescence per od .

 

 

CFU/ml data in Neg.Control and Pos.Control .

We dilute the neg.control and pos.control into the absorbance into 0.1, and we finish the following dilution according to the protocol. The protocol is easy to understand and there presents the data we record during experiment.

 

Table 11: The original absorbance of neg.control and pos.control after dilution in plate reader


Neg.Control Relplicate 1

Neg.Control Relplicate 2

Neg.Control Relplicate 3

Pos.Control Relplicate 1

Pos.Control Relplicate 2

Pos.Control Relplicate 3

LB+Cam

0.148

0.154

0.153

0.142

0.158

0.145

0.042

0.157

0.165

0.159

0.143

0.135

0.139

0.041

Table 12: The colony numbers in plates

Colony numbers

Final Dilution Factor

Neg.Control Relplicate 1

Neg.Control Relplicate 2

Neg.Control Relplicate 3

Pos.Control Relplicate 1

Pos.Control Relplicate 2

Pos.Control Relplicate 3

8*10^4

542

2300

1992

285

404

261

8*10^5

174

211

143

25

40

46

8*10^6

33

9

35

5

3

1

Final Dilution Factor

Neg.Control Relplicate 1

Neg.Control Relplicate 2

Neg.Control Relplicate 3

Pos.Control Relplicate 1

Pos.Control Relplicate 2

Pos.Control Relplicate 3

8*10^4

992

1488

660

267

209

221

8*10^5

140

288

79

16

22

22

8*10^6

8

53

16

2

13

1

Final CFU/ml

Neg.Control Relplicate 1

Neg.Control Relplicate 2

Neg.Control Relplicate 3

Pos.Control Relplicate 1

Pos.Control Relplicate 2

Pos.Control Relplicate 3

colony 1

2.01E+08

1.69E+08

1.97E+08

2.28E+07

3.20E+07

2.88E+07

colony 2

1.12E+08

3.27E+08

3.92E+07

2.14E+07

1.67E+07

1.77E+07

Figure 11 : The colony numbers per milliliter in 0.1 absorbance culture (600nm)

 

we selectively choose some data to calculate the final CFU/ml . The selective standard is according to the plate colony numbers which is between 30-300. After analyzing the final CFU/ml in the negative and positive control, we found that although the origin absorance are similar, there are some difference between the CFU/ml. we are not sure whether there exists pipetting errors during dilution process . But all the data we got shows that the expressing GFP consistantly in Pos.Control may affect the growth of bacteria .

Final conclusion

We could conclude that there are some relationships between the fluorescence/OD and fluorescence per particle, So it is definitely that we could use particle of cells to replace the Absorbance of cells. However, there is no obvious relationship between the particles of cells and the CFU/ml in culture. Because CFU/ml presents the numbers of survival cells and the bacteria which have relatively strong vitality. Compared with positive control, negative control obviously have a higher chance to express antibiotic resistant gene instead of the unnecessary GFP. So when transformed cells grow on the plates, there are more chances to survival in the antibiotic plates for cells who express more less unnecessary proteins.

Of course, there may exists some pipetting errors during dilution process, but the data we obtain from the experiment show that we may can’t normalize colony-forming units (CFUs) instead of OD during fluorescence measurements .

Figure 8 : The ratio of fluorescein/OD after cultivation for 6h (excitation light:485nm, emission light 530nm)

Figure 10 : The ratio of fluorescein/particle after cultivation for 6h (excitation light:485nm, emission light 530nm)
Figure 11 : The colony numbers per milliliter in 0.1 absorbance culture (600nm)