Arts & Crafts with a touch of bacteria
As we near the end of summer here in bonnie Scotland, the final design of our hydrogen gas production system is on everyone's mind. We want to create a small system that allows immediate use of the gas produced while also sustaining our bacterial cells. Our 'artificial leaf', inspired by a 2015 paper on biohydrogen (Das et al., 2015), was kindly 3D printed by the College of Engineering here in the University of Edinburgh. Affectionately called a 'hydrolyte', assembly of this prototype was reminiscent of arts and crafts lessons - though with a tad more bacteria and chemicals involved!
An aliginate hydrogel, containing Rhodobacter sphaeroides, will be placed on top of the red, grooved panel. The flow of medium within the grooves will nourish the culture. The white panel will be transparent in the final design to allow photosynthesis, and contains 2 small holes for insertion of syringes. Hydrogen gas extraction will be carried out through these syringes.
For the hydrolyte, the R. sphaeroides cells will be immobilized in the alginate hydrogel/fabric composite. We measured the pore size of different types of polyester fabrics to determine which would be best for our system. The 2015 paper used a range of fabrics with different pore sizes, the lower end being 250 micrometres. Das et al. also worked with an algal species that is larger in cell size than our bacterium. We chose to work with poly-cotton and poly-linen as the pore sizes were approximately 100 micrometres. As poly-silk is non-porous, it would be unsuitable due to a restriction of nutrient flow to the bacterial cells.
Coming up: level 2 assembly of our genetic constructs containing the hydrogen producing enzymes, and transformation of Rhodobacter through conjugation with E. coli.
Thank you to all those who have supported our project so far, stay tuned for more updates!
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