Description

Bacto-Aid

Our project faces the growing problems of both plastic pollution and the evolution of antibiotic resistant bacterias. Bacto-Aid is a sustainable concept with bacteria aiding us. We focused on producing a bandage, which consists of recombinant spider silk integrated with antimicrobial peptides, making it preventive towards infections. The plastic of which we wish to attach the spider silk, is biodegradable and produced in the lab as well.

The bacteriocins are the antimicrobial peptides in our hybrid silk. Resistance development in bacteria has been creating difficulties in curing infections with traditional antibiotics. The use of bacteriocins could shift some of the resistance pressure creating an alternative treatment. The bacteriocins act as bactericidal peptides through pore formation and interference with intracellular enzymatic reactions of specific target bacteria. Bacteriocins are essentially proteins that have bactericidal effect on specific strains. Today it is not used as an therapeutical antimicrobial compound, as it would be denatured in the stomach. Intravenous administration has been tested in mouse and shows promising results. Because proteins are translated from genes we can express desirable proteins in series. This allows us to incorporate bacteriocin proteins in between silk proteins. We, and the iGEM team of Stockholm, performed a MIC-test to observe the effect of our bacteriocins towards resistant bacteria. According to the test, the bacteriocins were proven to be quite effective. For further information about bacteriocins, read here.

The spider silk is chosen due to its angiogenic properties and proliferative effect on keratinocytes (skin cells), which is not seen in the traditional used gauze. The silk is produced by Nephila Clavipes made from repetitive protein expression of the dragline silk proteins. In order to obtain the ability to create silk , similar functions must be applicated to the E. Coli. Repetitive sequences of the genes MaSp1 and MaSp2 must be inserted into the plasmid of E. Coli. Synthesizing repetitive sequences are troublesome, and is difficult to do through 3A assembly, due to multiple scar-sites. To avoid scar sites, we tried to synthesize the silk with the help of the protocols provided by the 2015 iGEM team from UCLA, because they had already succeeded in producing spider silk from bacteria. The method gives way for hybrid silk, which consists of bacteriocins and spider silk with the same method. For further information about the spider silk, read here.

Poly-β-hydroxybutyrate (PHB) is a biosynthesized polyester, belonging to a group of bio-degradable plastics called polyalkanoates (PHA). PHB is non-toxic and has a high oxygen-permeability JAMBUNATHAN, P. & ZHANG, K. C. 2016. Engineered biosynthesis of biodegradable polymers. Journal of Industrial Microbiology & Biotechnology, 43, 1037-1058.<. The combination of different promoters and ribosomal binding sites has previously been shown to positively affect the yield of PHB. The yield has further been increased by the introduction of the pantothenate kinase BioBrick. By introducing a PHB secretion system into an E. coli plasmid we can achieve a production of PHB from the existing plastic producing BioBricks, that has left us with enough PHB to 3D print a part of a human jaw. The secretion system we introduce, use phasin as a transportermolecule for the secretion of PHB. Phasin binds to PHA's Hanisch, J., et al. (2006). "The Ralstonia eutropha H16 phasin PhaP1 is targeted to intracellular triacylglycerol inclusions in Rhodococcus opacus PD630 and Mycobacterium smegmatis mc2155, and provides an anchor to target other proteins." Microbiology 152(Pt 11): 3271-3280., which creates the possibility of its use when working with other types of bio-degradable PHA polyesters in bacteria.. For further information about PHB, read here.

This project was chosen due to the interest in synthetic spider silk. An article of interest that concluded antimicrobial effect of fused synthetic spider silk to human defenses became the pillar of our project Gomes, Silvia C, Isabel B Leonor, Joao F Mano, Rui L Reis og David L Kaplan (2011). “Antimicrobial functionalized gene- tically engineered spider silk.” eng. I: Bio- materials 32.18, s. 4255–4266. issn: 1878- 5905<. The idea of making PHB a part of our project as the plastic in the bandage, evolved from the desire to have an influence on solving the growing problem of plastic pollution. Bacto-Aid was the perfect project to make our two wishes come to life.

In the field of science, scientific reproduction is one of the most important aspects when confirming a hypothesis or theory. iGEM follows this specific scientific virtue by making it a part of both the bronze and gold criteria: the demands imply working with other team’s work. We took it further trying to reproduce parts of earlier iGEM team’s work: the 2015 UCLA team, the 2012 Tokyo Tech team, the 2013 Imperial College London and the 2015 Standford Brown team.

Why should consumers care?

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When designing our Bacto-Aid, it was important for us to ensure that Bacto-Aid consists of sustainable and renewable materials. The following survey shows, that Environmental friendly products are favored by 75 % of the consumers. With this in mind, our product satisfy the general opinion of the consumers.