With our Pichitecture bricks we wanted to generate a material that, when upscaled and integrated, can reduce CO2 emissions of the building industry. To make sure that our product has the potential to do so we created a model to see what would be needed to upscale our product.
The results showed that upscaling is possible. To produce 1000kg of our Pichitecture bricks, 337.5 L medium is needed. We decided to look specifically into the production of gelatin since a different version of the material we are creating was already produced and tested by Chelsea M. & Heveran et.al (2020). For 1000kg Pichitecture material, 33.75 kg gelatin and 3.38 kg CaCO3 are needed. Our model showed that if the gelatin was produced in a stirred tank reactor (CSTR) with roughly 900L working volume for 33.75kg, a supernatant volume of 11.250 m3 with a titer of 3 g/L is needed. We were also able to model the biomass needed to produce the necessary amount of CaCO3 based on an equation from Lamerand 2022. For 1000kg Pichtecture bricks 16.9 kg biomass is needed to produce 3.375 kg CaCO3.
Because we wanted to increase efficiency, we were interested in the approach of transferring our expression cassette into cyanobacteria with the hope to combine precipitation reaction and the expression of our polymers. Therefore, we generated a model to find out whether our chosen polymers would be suitable. It was unfortunately found that none of them were likely to be expressed.
The best news for us was that the expression of one of our polymers, spider silk, was achieved in Pichia pastoris and a second one, PHB, will be expressed in the upcoming days, after the wiki freeze. Therefore, we could prove that the material needed can be produced with a synthetic approach rather than having to harvest the spider silk from nature. Furthermore, one can explore the fixation of CO2 in the process of production when using cyanobacteria as a host for a plasmid with this insert.
We are proud that we can add our plasmids and expression cassettes to the iGEM bio brick database and hope that future iGEM teams will benefit from them.
To find out if our bricks even have the capacity to withstand the forces that they would endure, we started building prototypes and tested them. Here we played around with mixtures to find the one that would be most suitable for upscaling and usage. We had four rounds with different mixtures, learning from each round what to improve upon. We were able to produce bricks that were water resistant and endured the amount of weight we tested them with. We have also found combinations with sand and lignin which appear promising. This would further increase the positive impact of our bricks, as desert sand to this day is not widely used in the building industry and lignin is a waste product in the paper industry.
With our ongoing collaboration with our sponsor Wienerberger we are excited to find out how well our material performs compared to the other materials used in the building industry. As of the date of the wiki freeze, we are in the process of providing them with samples to test in their laboratory.