Description

Mars has become the new goal in the international space race during this century. Unlike earlier space races the goal is no longer to simply get there but has expanded into also staying there. This is due to the fact that the travel time and distance have increased, meaning that the mission to Mars will aim to create habitable structures to live in. This can further be seen as the pilot project for settlements in other parts of space.

To accomplish the goal of colonization, there are two options available:either bring the heavy materials from earth, which can be truly expensive (1) or use the resources already on Mars. Our project tries to explore the option of using the biomass available to bring the mission of colonizing Mars closer to reality.

Our suggestion is to use fungi-based building materials (mycotectures) to construct the structure, as the fungi can be grown on Mars. The fungi can be engineered here on Earth and transported as spores in the spacecraft, thereby mostly removing the cost of transport. The environment on Mars is not as hospitable as on Earth, meaning that both humans and materias will be exposed to radiation from space and needs to be protected from it. To this end we suggest melanin as part of the solution, as has been tried by the Stanford Brown 2016 team.
The temperature on Mars varies a lot due to seasonal changes and location, so if we were to grow the structure in its entirety at once it will be expensive, in energy needed for heating.Therefore we have instead developed a method suitable for growing smaller identical parts in a more controlled environment.

We are not the first group to attempt the production of mycotectures. We have sought out the Green Island, NY-based company Ecovative Design for guidance. They have been extremely helpful in determining growth and baking conditions, when producing the bricks. Furthermore, their genetics department has shared their protoplasting protocol and the Ganoderma resinaceum strain that they use themselves. In this regard, as we were limited in accessible enzymes we have tried to change Ecovative’s protocol to a potentially cheaper option. This has been done by leaving out one of the enzymes needed and trying to run the protoplastation with only one enzyme but in higher dosages.

To not only reach the desired solution of our project, but for us to also achieve satisfactory data, we needed to be able to discuss our ideas and plans. It was from the early start that we cooperated with the Stanford-Brown-RISD team for heavy troubleshooting and the sharing of supervisor knowledge. None of our projects would be what they are today if it wasn’t for the exciting meetings our two teams had early on in which we elaborated on each others ideas and helped finding the answers.

To minimize the different types of shapes that we need the fungi to grow into to assemble the final structure, we have based our design on geodesic domes, which are made up of repeating the same few different triangle pieces, with different side lengths. We have furthermore used COMSOL® for making a mechanical model of the final structure to confirm the structural integrity.
For this we used properties measured by industrial grade equipment at DTU as well as equipment of our own design.
We chose to primarily work with Aspergillus oryzae as working with Schizophyllum commune and Pleurotus ostreatus proved to be too difficult and time-consuming. When choosing the substrate for our bricks it was noted that A. oryzae is a known koji mold, so we chose different variants of rice for substrate. When going to Mars it would completely defeat the purpose of using mycotectures to have to transport tonnes of rice, of course. That is why we have planned for the final substrate on Mars to be cyanobacteria as they produce O₂ from carbon dioxide and can function as a carbon source. The growth temperature used for growing the bricks in the lab where 28°C in darkness as that was the temperature found to be the most beneficial for the fungus.

Modelling the behaviour of fungal growth provides a quicker way of determining conditions as compared to going into the lab and testing all combinations. We have therefore developed two models that study the hyphal growth in details and that follows the biomass development in a more generalized view.

To modify the fungi with the needed properties we have transformed different genes in E. coli (Dh5-ɑ) for Gibson assembly (and later on 3A assembly), as this proved more efficient that Crispr9 (2). To ensure our bacteria held the gene correctly, we used PCR and gel electrophoresis on our samples before sending them to sequencing.