Hong Kong team develops yeast, gelatin and sand "living" material for Mars construction

Centre · 1Scientists in Hong Kong say they have developed a low-cost "living" building material made from genetically engineered yeast, gelatin and sand that can be 3D printed under conditions simulating Mars. 1 Centre · 2The study was published last month in Chem Circularity, a Cell Press journal, under the title 'Engineered living building material for low-energy construction on Mars'. 1 2 Centre · 1The material was developed by Professor Qiu Jishen and his team at the Hong Kong University of Science and Technology, with scientists from Hong Kong Polytechnic University. 1

Centre · 2The material combines sand or other granular particles with a gelatin hydrogel and Saccharomyces cerevisiae yeast whose surface is modified to display adhesive proteins, including mussel foot proteins. 1 2 Centre · 2It hardens during freeze-drying (at −55°C and 0.0001 atm for 48 hours in the tests), leaving a porous gelatin scaffold with yeast cells embedded in its walls. 2 1 Centre · 2The optimised formulation, with 25% biological components in the added solids, had a compressive strength of about 12 MPa, around 170 per cent higher than the control, and a flexural strength of 6 MPa. 1 2

Centre · 2The researchers printed a small beacon-like structure, 45mm high and 30mm in diameter, in a chamber at 0.01 atmospheres and minus 30 degrees. 1 2 Centre · 2Processing is far less energy-intensive than sintering Martian soil at about 1,000°C: the team estimated that 1 cubic metre would need under an hour of solar-panel operation versus several days for sintering, and the paper puts the energy requirement several tens of times lower. The paper cautions this is a first-order estimate that excludes microbial cultivation, nutrient supply, bioreactor pressurisation and other operations. 1 2 Centre · 2The material can be recycled: after crushing, rehydrating and gentle heating, fourth-generation samples kept a compressive strength of about 11.8 MPa, and the yeast stayed viable across repeated recycling. 1 2

Centre · 2The material still depends on Earth: it relies on porcine gelatin and externally supplied nutrients. Qiu said 1 cubic metre would need only tens of kilograms of Earth-supplied raw materials, 70 to 80 per cent of it gelatin, and that this could in theory fall to zero if Martian methane, carbon dioxide and water ice could be converted into gelatin or nutrients. 1 2 Centre · 2Qiu's team describes the current material as a structural component rather than a complete habitat. Open questions include radiation tolerance, permeability, thermal conductivity, long-term durability, tensile behaviour and full-scale fabrication. Zhu Xiaohong of Beijing University of Technology, who was not involved, called it an important direction but said applications are not yet mature. The team also sees uses on Earth, such as Antarctic research stations. 1 2