Part:BBa_J364000

Test Device 1 for the iGEM InterLab Study

This is a GFP expressing constitutive device for the 2017 iGEM InterLab study. It is called Test Device 1 for the study for easy reference.

This device is stored in pSB1C3 for the InterLab and is fully BioBrick compatible.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  INCOMPATIBLE WITH RFC[12]

  Illegal NheI site found at 7
  Illegal NheI site found at 30
  
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal BsaI.rc site found at 705
  

Team NAWI_Graz 2019: GFP dynamics of transformed Escherichia coli strains in LB broth

Background

In Team NAWI_Graz 2019 characterization, we found that in normal growth/incubation condition (37 ^oC, LB agar) BBa_J364000-transformed Escherichia coli BL21 cells had the highest GFP expression in comparison to BL21 Star and Top 10 strains. In order to confirm that we have measured the GFP Flourescence of those three strains over 44 hours period.

Experimental Design

We used three different strains of transformed E. coli (Top10,BL21 and BL21 Star) for this study. Transformed strains were incubated in 15 mL LB broth 37 ^oC overnight. Next day they were used to inoculate a 50 mL LB to OD₆₀₀=0.1. The cultures were then incubated at 37 ^oC, 140 rpm and samples were taken every 4 hours for 2 days to determine the green fluorescence protein (GFP) fluorescence intensity at 510 nm.

Result and Findings

• There are significant differences of GFP expression in different strains of E. coli (Top10, BL21, BL21 Star)
• The broth became ligh green in color under natural light after around 14-18 hours of incubation time.

          Figure 1: GFL Flourescence and OD600 Measurements with GFP containing E.coli strains and non GFP containing E.coli strains (control))

Figure 2: ~14 hours old GFP-transformed E. coli strains (Left: Top10, Middle: BL21, Right: BL21 Star)

Improvement

• Group: iGEM Team UESTC-China 2019
• Author: Qiuyun Huang, Zixin Wang

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We improved this reporter device into a surface presentation + reporting system (BBa_K3034007) by fusing GFP with INPNC so that the team could make reporter genes through GFP and anchor the target protein to the bacteria outer membrane for more applications.

Ice nucleation protein (INP) is a secretory outer membrane protein from Pseudomomas syringae P. flurorescens and several other Gram—negative bacteria[1]. INP can anchor one or more "passenger proteins" to the outer membrane of E.coli DH5α. The fixation of exogenous proteins on the cell surface through INPNC can not only greatly improve the efficiency of enzymatic reaction, but also avoid the degradation of exogenous proteins by intracellular enzymes of host cells.

Besides, we added a segment of linker between INPNC and GFP to ensure that two adjacent domains do not sterically interfere with one another.

Quantitative detection of fluorescence

We first cultured the bacteria overnight and made OD600 uniform. We ultrasonic broken, centrifuged and respectively resuspend precipitation to measure the distribution of GFP in E.coli DH5α carrying BBa_J364000 and E.coli DH5α carrying BBa_K3034007 (Fig.1).

Fig.1. The relative fluorescence intensity of E.coli DH5α carrying BBa_J364000 and E.coli DH5α carrying BBa_K3034007. The relative fluorescence intensity= Fluorescence of precipitation/ (Fluorescence of supernatant+ Fluorescence of precipitation)×100%.

The results showed that both precipitation and supernatant contained relatively strong GFP after centrifugation. Moreover, the distribution of GFP in E.coli DH5α with BBa_K3034007 was not significantly different from that in E.coli DH5α with BBa_J364000. But, the content of GFP in the broken E.coli DH5α with BBa_K3034007 was higher than that in the E.coli DH5α with BBa_J364000.