The world is reaching the tipping point beyond which climate change may become irreversible. If this happens, we risk denying present and future generations the right to a healthy and sustainable planet – the whole of humanity stands to lose.Kofi Annan, Former Secretary-General of UN
We are the iGEM 2022 team from Vienna, consisting of 11 students from diverse collegiate backgrounds, combining our origin stories in the attempt to tackle a major contributor to worldwide carbon emissions: 11% of total carbon emissions can be attributed to production of building materials.
Biomineralization and Carbon Fixation: Cyanobacteria possess the remarkable ability to take carbon dioxide from the air and convert it to a solid mineral, calcium carbonate. They manage it with a bacterial microcompartment called a carboxysome, primarily with the enzyme RuBisCo. These minerals are the solids which just need some connecting to make the material we want.
Creating Crosslinks: A variety of biopolymers came to mind when we thought of sticky proteins that could hold our building material together, but finally, we settled on the following: spider silk, gelatin and polyhydroxybutyrate (PHB). They are here to act as a “glue” to the produced minerals. And who produces them? Hidden in the name of our project, the yeast Pichia pastoris.
Recycling and consideration of circular economies: Various industries create waste products that can, as of today, not be used, or are severely underutilized. However, FEAR NOT! In our project, we also welcome such materials in our brick-building concept. Lignin, a waste product of the paper and pulp industry, sand (desert and river varieties) and, kindly provided by our sponsor Wienerberger, rubble from construction sites all have a place in our material to test if their use could improve the properties of what we create.
We use Golden Gate Assembly to engineer Pichia pastoris to express sticky biopolymers. In the process of assembly, we create novel plasmids for spider silk MaSp, gelatin, as well as PHB. Meanwhile, we look into whether we can create plasmids for Synechocystis PCC 6803, so, in potential applications of the project, it could both perform biomineralization and protein expression.
Mixing together our ingredients in different proportions, we create bricks, and test their material properties to see if they perform in accordance to the standards set by stakeholders. We also create bricks with our cyanobacteria cultures to see whether the brick properties change upon addition. To further solidify our concept, we model two approaches: an exploration of whether we can express our polymers in Synechocystis via a machine learning model, and a putative upscaling model based on existing literature to see what material is needed for one ton of Pichitecture.
Our project sets out to offer a sustainable alternative to current production processes. With the help of microorganisms, we can contribute to the creation of sustainable building materials, reducing harm to the environment and the strain from copious carbon emissions produced by standard processes.
We sincerely hope that our concept of building materials produced with biomineralization and usurping metabolic pathways of various microorganisms can inspire further work to reduce CO2 emissions in this sector. Additionally, we want our wide spectrum of biopolymers used to motivate other researchers to dream big and try truly adventurous concepts in their projects!