Enabling Clonal Analyses of Yeast in Outer Space by Encapsulation and Desiccation in Hollow Microparticles

Simon Ng; Cayden Williamson; Mark van Zee; Dino Di Carlo; Sergio R Santa Maria

doi:10.3390/life12081168

Enabling Clonal Analyses of Yeast in Outer Space by Encapsulation and Desiccation in Hollow Microparticles

Life (Basel). 2022 Jul 31;12(8):1168. doi: 10.3390/life12081168.

Authors

Simon Ng^{1

2}, Cayden Williamson¹, Mark van Zee¹, Dino Di Carlo^{1

3

4}, Sergio R Santa Maria^{5

6}

Affiliations

¹ Department of Bioengineering, University of California-Los Angeles, Los Angeles, CA 90095, USA.
² Space Life Sciences Training Program, NASA Ames Research Center, Mountain View, CA 94035, USA.
³ Department of Mechanical and Aerospace Engineering, University of California-Los Angeles, Los Angeles, CA 90095, USA.
⁴ California NanoSystems Institute (CNSI), University of California-Los Angeles, Los Angeles, CA 90095, USA.
⁵ Space Biosciences, NASA Ames Research Center, Mountain View, CA 94035, USA.
⁶ KBR, Fully Integrated Lifecycle Mission Support Services, Mountain View, CA 94035, USA.

Abstract

Studying microbes at the single-cell level in space can accelerate human space exploration both via the development of novel biotechnologies and via the understanding of cellular responses to space stressors and countermeasures. High-throughput technologies for screening natural and engineered cell populations can reveal cellular heterogeneity and identify high-performance cells. Here, we present a method to desiccate and preserve microbes in nanoliter-scale compartments, termed PicoShells, which are microparticles with a hollow inner cavity. In PicoShells, single cells are confined in an inner aqueous core by a porous hydrogel shell, allowing the diffusion of nutrients, wastes, and assay reagents for uninhibited cell growth and flexible assay protocols. Desiccated PicoShells offer analysis capabilities for single-cell derived colonies with a simple, low resource workflow, requiring only the addition of water to rehydrate hundreds of thousands of PicoShells and the single microbes encapsulated inside. Our desiccation method results in the recovery of desiccated microparticle morphology and porosity after a multi-week storage period and rehydration, with particle diameter and porosity metrics changing by less than 18% and 7%, respectively, compared to fresh microparticles. We also recorded the high viability of Saccharomyces cerevisiae yeast desiccated and rehydrated inside PicoShells, with only a 14% decrease in viability compared to non-desiccated yeast over 8.5 weeks, although we observed an 85% decrease in initial growth potential over the same duration. We show a proof-of-concept for a growth rate-based analysis of single-cell derived colonies in rehydrated PicoShells, where we identified 11% of the population that grows at an accelerated rate. Desiccated PicoShells thus provide a robust method for cell preservation before and during launch, promising a simple single-cell analysis method for studying heterogeneity in microbial populations in space.

Keywords: Saccharomyces cerevisiae; cell encapsulation; hydrogel; microbes; microfluidics; preservation; single-cell analysis; space biology.

Grants and funding

BioSentinel Project/NASA/NASA/United States