Team:StanfordBrownSpelman/Cellulose Acetate

Results

We were able to extract total DNA from P. fluorescens and amplify the four acetylation genes.

The prefix and suffix were added onto these PCR products, and then they were inserted (separately) into pSB1C3 for biobricking (see Submitted Bricks).

We were also able to show that the pUCD4 shuttle vector was effective in providing antibiotic resistance to G. hansenii, showing that our transformation protocol was effective. By plating both transformed and untransformed cells on antibiotic selection plates and using colony PCR to screen for the presence of the plasmid, we found that pUCD4 was effective at providing resistances to tetracycline and streptomycin.

Ultimately, we were unsuccessful in our attempts to ligate the wss genes into the pUCD4 plasmid: we were therefore unable to produce cellulose acetate biologically in G. hansenii. Future attempts could be made, possibly using a different shuttle vector. However, we continued to investigate the use of pure, unmodified bacterial cellulose as a building material. The first step in working towards producing our building material was to grow cultures of cellulose producing bacteria in sterile trays. After these cultures grew for 1-2 weeks, we removed the produced cellulose sheet from the culture to test various methods of drying. We experimented with drying the sheet in an oven, to produce an extremely thin layer of cellulose. We also wrapped fungal mycelium blocks provided by Ecovative, which we intend to be the body of our UAV, with wet cellulose, and allowed the cellulose to dry on its own. This will provide the platform for us to alter the biomaterial for flight, by, for example, making it waterproof.

One alteration we intend to make in order to produce a functional UAV is to draw circuits on the biomaterial to conduct electricity. In order to produce a biodegradable circuit, we worked with a company called AgiC, which prints circuits out of silver nano particles (see our Building a UAV page for a full circuit). By taking silver ink and painting it on to our bacterial cellulose, we were able to test the conductive capabilities of our building material.

Additional Information

Interested in what we've been working on and want to find more relevant information? Check out some of the following sites, companies, and people who either aided us in our production of biomaterials or collaborated with us in working to produce a viable biological unmanned aerial vehicle.

● Click here for a list of submitted biobricks, the four genes found in P. fluorescens responsible for the acetylation of the cellulose polymer. These genes are all found individually in the biobrick backbone and are fully biobrick compatible.

● Click here for more information on the specific protocols we used for working with G. hansenii and bacterial cellulose, including our recipe for Acetobacter Medium, an electroporation transformation protocol, and instructions on generating, cleaning, and drying bacterial cellulose.

Building a Biological UAV

Our team modeled, prototyped, and collaborated with Ecovative Design to grow a mycelium-based chassis for our biological drone. For more information on this process, including part designs, links to open source model files, and photographs of the biological and biodegradable UAV we built and flew, click here!

References

1. Fischer S et al. (2008) Properties and Applications of Cellulose Acetate. Macromol. Symp. 262: 89-96. DOI: 10.1002/masy.200850210

2. Ross P et al. (1991) Cellulose Biosynthesis and Function in Bacteria. Microbiological Reviews 55: 35-58. PMID: 2030672


3. Spiers AJ et al. (2003) Biofilm formation at the air–liquid interface by the Pseudomonas fluorescens SBW25 wrinkly spreader requires an acetylated form of cellulose. Molecular Microbiology 50: 15-27. PMID: 14507360


4. The United States Pharmacopeial Convention. Cellulose Acetate. USP-NF. 2013.


5. Hall PE et al. (1992) Transformation of Acetobacter xylinum with Plasmid DNA by Electroporation. Plasmid 28: 194-200.
 PMID: 1461938


6. Close TJ et al. (1984) Design and Development of Amplifiable Broad-Host-Range Cloning Vectors: Analysis of the wir Region of Agrobacterium tumefaciens Plasmid pTiC58. Plasmid 12: 111-118. PMID: 6095350


7. Spiers AJ et al. (2013) Cellulose Expression in Pseudomonas fluorescens SBW25 and Other Environmental Pseudomonads in Cellulose - Medical, Pharmaceutical, and Electronic Applications. DOI: 10.5772/53736

      

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