Team:SDU-Denmark/Tour50

Results

If it looks like rubber and smells like rubber, it probably is rubber

The hours of work throughout the summer are justified by the excitement of new results. Each team member feels a distinct sense of pride. A peculiar sense of ownership. Accomplishement, even.

We invite you to dig deeper to view each an every one of our results and to experience our excitement. But before you do that, the following page points to our main accomplishments and presents a quick glance at the most cherished of our results: the production of Bacteriorganic Rubber.

In order to accomplish our goal, we had two subprojects: Optimization of the MEP pathway; in order to increase the amount of buildingblocks (IPP IPPIsopentenyl pyrophosphate and DMAPP DMAPPDimethylallyl pyrophosphate) for the rubber synthesis, and introduce the rubber polymerization enzyme, HRT2 prenyltransferase of Hevea brasiliensis, into the E. coli bacteria.

Optimization of MEP pathway
We attempted to optimize the MEP pathway by overexpressing the genes (Dxs. DXS1-deoxyxylulose-5-phosphate synthase and IspG IspG1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase) that our model predicted to be rate limiting. Unfortunately, we weren’t successful in building a construct containing ispG, and therefore could not test the consequences of overexpressing this particular gene. However, we did successfully build a construct that overexpressed the first rate-limiting step (Dxs). In order to verify if the IPP and DMAPP concentrations increased by overexpression of the dxs gene, we did gas chromatography (GC). Though efforts were made, we weren’t able to prove or disprove that more IPP and DMAPP were produced due to technical problems.

Figure 1. Rubber synthesis
The HRT2 prenyltransferase of Hevea brasiliensis was successfully introduced into the E. coli bacteria. H¹-NMR was performed to detect rubber produced by our bacteria in comparison with a polyisoprene standard as the positive control and wild type E. coli as the negative control. The results show strong indications that we have rubber-producing bacteria (Fig. 1). A second round of H¹-NMR stated that the result was reproducible, and we therefore can proudly pronounce that our CPS bacteria produces rubber; Bacteriorganic Rubber!

Figure 2. Controllable constructs
An important part of the design of our constructs was the capability to control the expression of genes converting the fast growing bacteria to a rubber producing suicidal (at least in theory) bacteria. We therefore placed the expression of Dxs under the control of the lac-promoter and the expression of HRT2 under the control of the Ara-promoter. We successfully proved that addition of IPTG induces the expression of Dxs, and addition of arabinose induces the expression of HRT2 (Fig. 2). A cell viability experiment showed that the cells apparently did not die, as expected, when producing rubber. This surprising result might be due to the very low concentration of rubber produced in the cells. But never the less rubber is indeed produced!

Added BioBrick parts and devices
iGEM primarily concerns the field of synthetic biology, and one of the ideals of iGEM is the vision of a large registry, where all imaginable DNA sequences usable for a synthetic microbiologist can be found in easy-to-use standardized parts. During our project, we have added 4 new basic parts and 13 devices to this registry. Dig deeper to explore the different Bricks and Submitted parts.

A different wiki
One of our stated goals during this year’s iGEM competition was to invent a novel and intuitive approach to the iGEM focus of passing on knowledge to a wide and varied audience through the use of a web interface. Through a lot of hard work and great feedback, we are confident that this goal has been accomplished and that our tour is to your liking, dear reader.

Jamboree result
At the Regional Jamboree in Lyon our project achieved a Gold medal, advancement to the World Championship in Boston and even a special award for Most Improved Registry Part. A further description of the goals and our solutions can be found in the ‘Judging Criteria’ section (Dig deeper).

Alongside all these achievements, we learned more about the hard work it requires to work together in large groups and received invaluable lab and life experiences.

Dig deeper to see all our results in details. Or go to the next chapter to see the future perspectives of our project.