Worth its Salt?: Testing the Effects of Mars and Europa-Analog Salts on the MinION Sequencer

The Oxford Nanopore MinION, a portable DNA sequencer utilizing nanopore technology, has attracted attention from the astrobiological community as a potential life detection tool. However, nanopore sequencing technology—which was not created for space exploration—hasn't been fully established as a viable spaceflight instrument. Previous research has demonstrated the MinION's ability to withstand long journeys to remote field sites on Earth (Johnson et al., 2017), its tolerance of radiation (Sutton et al., 2019), as well as its ability to perform in altered gravity (Castro-Wallace et al., 2017). Yet the harsh conditions of spaceflight and extreme conditions on other worlds still pose significant challenges. Because many promising targets for astrobiology are highly saline environments, we decided to probe the MinION's resilience to varying levels of Mars and Europa-analog salts, including perchlorate and calcium sulfate. We added brines made with nuclease-free water to samples of standard lambda DNA to simulate salt concentrations, then analyzed the performance of the sequencer by comparing total number of reads and signal-to-noise ratio. We found that perchlorate is far harsher on the MinION system than calcium sulfate, and that reads decrease as salt concentration increases. Interestingly, this analysis offers a counterpoint to Sutton et al.'s work, which suggested that the MinION could far more easily tolerate the expected radiation dose on Mars than on Europa. These results demonstrate the importance of adding a desalting step in sample preparation if using nanopore technology to detect biosignatures.

Works Cited:

Castro-Wallace et al., 2017, Scientific Reports, (7), 18022.

Johnson et al., 2017, J Biomol Tech, (1):2-7.

Sutton et al., 2019, Nature Scientific Reports, (9), 5370.