Composite

Part:BBa_K3331013

Designed by: Wang Weizhe   Group: iGEM20_XJTU-China   (2020-10-22)
Revision as of 21:20, 26 October 2020 by Cycling (Talk | contribs)

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E.coli galU+B.S pgmA

This part can increase the yield of EPS. The yield of EPS can be significantly increased by overexpressing two key enzymes galU and pgmA at the same time. The part galU is from Escherichia coli YJ4. The part pgmA is from Bacillus subtilis subsp. subtilis str. 168. Reference: Levander Fredrik et al. Applied and environmental microbiology,2002,68(2).


Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    COMPATIBLE WITH RFC[25]
  • 1000
    COMPATIBLE WITH RFC[1000]


Overview

In order to increase the production of exopolysaccharides (EPSs), we altered the levels of enzymes in the central metabolism. We selected and overexpressed two key enzymes, galU and pgmA at the same time. And we found we successfully enhance the production of EPSs in E.coli.DH5α

Figure 1:Plasmid we have constructed for galU&pgmA validations.
Figure 2:Designed verification circuit.

Characterization

The test plasmid was constructed by Golden Gate Assembly and was confirmed by colony PCR. The length of E.coli galU fragment is 981bp, and the length of B.S pgmA is 1875bp. The following results showed successful constructions.

Figure 1:PCR confirmation of the designed plasmid.

Our strain was cultured in ampicillin-resistant LB medium with strictly control variables. We stop the culture after 24 hours of culture. We measure the expression of EPS and the level of gene transcription during this period. RT-qPCR was conducted to test their expressions. And we can see these two genes were transcribed successfully.

Figure 2:RT-qPCR result of pgmA and galU.

Anthrone sulfuric acid method was used to detect EPS yields. Compared with the blank strain, the EPS yield of the engineering strain increased by 54.9%.The results of this study clearly show that it is possible to enhance the production of EPSs in DH5α by altering the expression of B.S. pgmA and E.coli galU.

Figure 3:Detection of the expression of EPS.

We also measured the growth of DH5α transferred into the plasmid by enzyme labeling instrument. We measure the OD value of bacteria every hour under the wavelength of 600nm and fit the results. It was compared with the blankDH5α and the growth curve was drawn.

Figure 4:Growth curve of strains.
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