DOI: 10.5061/dryad.rc63v
title: Data from: A submersible, off-axis holographic microscope for detection of microbial motility and morphology in aqueous and icy environments

description: 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.
description: 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 brine kept overnight at +4 C with the addition of 1/2 strength 2216 marine medium. File 2015.03.30 05-28. Data for Figures 8F in paper and Video 8.Archive.zipBrine at -4CMalene Bay brine kept overnight at -4 C with no additions. File 2015.03.28 08-11. Data for Figure 8D in paper and Video 6.Archive.zipBrine in situBrine in situ at Kobbefjord. No additives or treatments. Data file 2015.03.26 11-10. Data for Video 3.Archive.zipBrine in situ+serineKobbefjord brine + serine in situ. Data file 2015.03.26 11-16. Data for Fig. 8B.Hologramssubset.zipMB Brine + serineMalene Bay brine + serine. Data file 2015.03.25 06-40. Data for Fig. 8 A, C and Videos 2 and 5.Hologramssubset.zipMB Brine in situMalene Bay brine, no treatments, recorded in situ. Data for Fig. 6 A. Data file 2015.03.27 10-46.HolgramsSubset.zipMalene Bay eukaryotesMalene Bay, unmodified, showing eukaryotes. Data for Fig. 6. Data file 2015.03.25 10-10Hologramssubset.zipFourierMaskNuukDataFourier mask for data sets.