Lab safety:

Before starting the experimental work of the new iGEM season, all of our team members must pass the safety and security training that is carried out by senior supervisors who have significant lab work experience. In our laboratory, students are working under constant supervision by our instructors while following the regulations and norms of experimental work provided by the Institute of Technology in University of Tartu. The experimental work is carried out in a Level 1 Biosafety laboratory. Our team works only with non-pathogenic organisms belonging to the White List.

Project safety

In our project “Space Yeast” we are working with genetically modified baker’s yeast Saccharomyces cerevisiae and bacteria cloning-compatible strains of Escherichia coli. Both of these belong to the iGEM White List in order to make the experimental work and subsequent implementation safer. We are also using the tyrosinase gene from Bacillus megaterium, which is also considered not harmful to humans or the environment. We follow biohazard waste disposal rules to ensure that no genetically modified cells are released from the lab.

Our project consists of three different approaches to create three yeast strains. Each of them poses a very low risk of spreading the final product into the environment. The first approach is based on producing melanin in yeast cell cytoplasm by overexpression of a bacterial tyrosinase. For this we use the pRS306 plasmid vector as a backbone for the final construct. As a shuttle vector that can be used in both yeast and bacteria, pRS306 contains both E. coli origin of replication and an antibiotic resistance gene. Therefore, this poses a possible risk of spreading antibiotic resistance genes in case either yeast strains or bacteria used to clone the construct are released into the environment. To mitigate this risk, we use a different vector backbone in the other two approaches, where bacterial origin and the antibiotic resistance gene are removed from the plasmid before yeast transformation.

Although not in the scope of our this year’s iGEM project, there is a risk of the engineered yeast cells being released within the spacecraft. This may affect astronauts’ health. In order to minimize this risk, we propose to use special containers with a double lock system.

Dual use

Our project does not produce any new virulence factors. We aimed to engineer yeast strains that produce melanin, which is non-toxic and not harmful to the environment. While melanin in yeast is aimed to provide protection against UV and ionizing radiation, its synthesis in the engineered yeast is controlled by galactose-inducible promoters. For this reason, our yeast strains maintain the radiation resistance only in highly specific conditions, limiting their use in other environments for other purposes. Production of melanin includes synthesis of compounds that are toxic to the yeast cells. Our project attempts to limit the cytotoxic effect by introducing nanoparticle scaffolding. This allows to create a physical barrier and to control the localization of the malignant metabolites. Successful solutions on how to overcome the toxicity of certain biosynthesis pathways could, in principle, be used in other cell factories and this could open new possibilities to produce harmful compounds using synthetic biology. However, this risk at the moment is only hypothetical.