Yeast in Space
Humans and yeast have traveled together through a long history of terrestrial explorations and will continue to do so as mankind explores space. Candida species of yeast accompany us as part of our microbiome and humans will find ways to carry Saccharomyces species of yeast with them on their space travels in order to make bread and beer/wine. In addition to its health and gastronomic roles, yeasts have also proven to be highly useful tools for exploring the biologic impacts of the space environment. An international consortium has produced a library of clones in which each of the ~6, 200 known open reading frames of the yeast Saccharomyces cerevisiae has been systematically deleted. For fitness profiling, this library of clones is exposed to a stressor such as galactic cosmic radiation, changes in mass transport, or shear stress and allowed to proliferate for up to 100 generations. By systematically identifying those genes and gene pathways that are required to resistant exposure to spaceflight stimuli, the mediating and buffering gene pathways can be delineated, which can be augmented experimentally to identify countermeasures. At the end of the exposure, the relative abundance of each clone is enumerated by next-generation sequencing. Those clones carrying a deletion of a gene needed for survival in the presence of spaceflight stimuli have reduced growth or fitness. Secondarily, these techniques can be applied to assess drug-induced changes during spaceflight. Broad stimulus libraries, including radiation types and radiomimetics, collected and assessed at 20+ generations are available for comparison.
