Results
The diagram below is the outline of achievments we already made and next plan in future.
As we known, carbon sequestration using algea or micro seaweads is a hot field with great difficulties and challenges. Our project aims to build an ideal algae with increased ability of carbon dioxide fixation and decreased the recyle of fixed bioproducts. It is a big and long-time project with lots of work to do and with great challenges.
Inspiringly we have already moved forword with several critical and important steps in the past one year:
1. Fisrt of all, our team successfully cultured two of single-cell micro seaweeds selected from several candidates. One is an eukaryotic algae of dunaliella salina, and the other one is a prokaryotic alges of synechococcus sp. PCC 7002 that finally used in this project. Sequentially we did some basic characterizations for them like growth curve measurements and tests of antibiotic sensitivity.
2.Most importantly we constructed a modularized basic expression vector and prepared a series of biobrick compatible parts like promoters, terminators and cassettes of selectable markers. On base of these works, we can easily make compatible expression vectors and test different regulation parts in both eukaryotic and prokaryotic alges or even in other chassis. And we made a workable expression vector for synechococcus sp. PCC 7002.
3.We tried several commonly used transformation methods like electroporation, natural transformation and biolistic transformation, and succesfully transformed and expressed a reporter gene of EGFP and two carbon fixation genes which may help to promote the carbon fixation efficiency of this algae.
4.In order to increase the density help the alga to sink as designed, we should express metal binding proteins at the surface for absorption of metal irons. Because of the lag of some fundamental works, we fisrt use Escherichia coli as a model instead of synechococcus sp. PCC 7002 to test our assumptions. We quickly validated most of our design in E.coli cooperated with team of ASTWS-China.
5. And another remarkable work done by our team is that we designed and made a prototype of device for algae cultivation. Compared to the flask culture method, it has some obvious advantages including less cost, more biomass and more efficiency of space usage. Moreover it’s easier to be scaled up from lab to factory.
Of course, there’s lots of validation work left and optimization work to do in future, here we listed most of the important works we plan to do.
1. The results showed that the gene expression level in this algae is much lower than other commonly used chassis. We plant to cellect and screen as much parts as possible for this new chassis to promote the gene expression. And the codon optimisations for target genes might also be critical for their expressions as said by some references.
2. We have already expressed two carbon fixation genes in this algae and verified by PCR and western-blot, but there is still lack of direct evidence that this engineered algae has been improved its ability of photosynthesis or carbon fixation. And there are other genes involved in agar or cellulose synthesis, which might be much more suitable for our project. These validation or optimization works also need to be done in future.
3. Another important work that need to be done is the experiments of metal binding and sinking using synechococcus sp. PCC 7002 directly.
4. Finally is the work about the prototype of our cultivation device. We will test this device in a larger scale throuth parallel connection of numerous single devices or scale up the size of single device. And we will test the ‘sinking assumption’ of our transgenetic algae in a simulate environment of ocean using this scaled-up device.
