Data from: A submersible, off-axis holographic microscope for detection of microbial motility and morphology in aqueous and icy environments

• Main Authors: Lindensmith, Christian A., Rider, Stephanie, Bedrossian, Manuel, Wallace, J. Kent, Serabyn, Eugene, Showalter, Gordon M., Deming, Jody W., Nadeau, Jay L.
• Format: Dataset
• Language: unknown
• Published: 2017
• Subjects: astrobiology; sea ice; motility; marine microorganisms; Holocene; Greenland; Nuuk; Sea ice
• Online Access: https://zenodo.org/record/4937128; https://doi.org/10.5061/dryad.rc63v

Sea ice is an analog environment for several of astrobiology's near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM) that is capable of resolving individual bacterial cells, and demonstrated its utility for immediately imaging samples taken directly from sea ice at several locations near Nuuk, Greenland. In all samples, the appearance and motility of eukaryotes were conclusive signs of life. The appearance of prokaryotic cells alone was not sufficient to confirm life, but when prokaryotic motility occurred, it was rapid and conclusive. Warming the samples to above-freezing temperatures or supplementing with serine increased the number of motile cells and the speed of motility; supplementing with serine also stimulated chemotaxis. These results show that DHM is a useful technique for detection of active organisms in extreme environments, and that motility may be used as a biosignature in the liquid brines that persist in ice. These findings have important implications for the design of missions to icy environments and suggest ways in which DHM imaging may be integrated with chemical life-detection suites in order to create more conclusive life detection packages. Chemotaxis Middle ChamberHolograms of Malene Bay brine sample exposed to a bottom-to-top serine gradient (data file 2015.03.30 06-28) Data for Fig. 9 B, C in paper and Video S9.Holograms.zipChemotaxis Side ChamberBrine sample exposed to a right-to-left serine gradient. Data file 2015.03.30 06-14. Data for Fig. 9 A in paper.201503300614.zipSeawater at +4CMalene Bay seawater kept overnight at +4 C with the addition of 1/2 strength 2216 marine medium. File 2015.03.30 05-58. Data for Figures 7 and 8E in paper and Videos 4 and 7.201503300558.zipBrine at +4 CMalene Bay ...