Hostname: page-component-586b7cd67f-gb8f7 Total loading time: 0 Render date: 2024-11-27T22:17:47.824Z Has data issue: false hasContentIssue false
  • English
  • Français

Gypsum-hosted endolithic communities of the Lake St. Martin impact structure, Manitoba, Canada: spectroscopic detectability and implications for Mars

Published online by Cambridge University Press:  18 September 2014

T. Rhind ,
J. Ronholm ,
B. Berg ,
P. Mann ,
D. Applin ,
J. Stromberg ,
R. Sharma ,
L.G. Whyte  and
E.A. Cloutis
T. Rhind
Affiliation:
Department of Geography, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
J. Ronholm
Affiliation:
Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
B. Berg
Affiliation:
Department of Geography, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
P. Mann
Affiliation:
Department of Geography, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
D. Applin
Affiliation:
Department of Geography, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
J. Stromberg
Affiliation:
Department of Earth Sciences, Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario N6A 5B7, Canada
R. Sharma
Affiliation:
Department of Geography, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
L.G. Whyte
Affiliation:
Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
E.A. Cloutis*
Affiliation:
Department of Geography, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
*
e-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

There is increasing evidence that Mars may have once been a habitable environment. Gypsum is targeted in the search for Martian biosignatures because it can host extensive cryptoendolithic communities in extreme terrestrial environments and is widespread on Mars. In this study the viability of using different spectroscopy-based techniques to identify the presence of gypsum endolithic communities was investigated by analysing various cryptoendoliths collected from the Lake St. Martin impact crater (LSM), a Mars analogue site found in Manitoba, Canada. Concurrently, the cryptoendolithic microbial community structure present was also analysed to aid in assigning spectroscopic features to microbial community members. Two main morphologies of endolithic communities were collected from gypsum deposits at LSM: true cryptoendolithic communities and annular deposits on partially buried boulders and cobbles <1 cm below the soil surface. Endolithic communities were found to be visibly present only in gypsum with a high degree of translucency and could occur as deep as 3 cm below the exterior surface. The bacterial community was dominated by a phylum (Chloroflexi) that has not been previously observed in gypsum endoliths. The exterior surfaces of gypsum boulders and cobbles are devoid of spectroscopic features attributable to organic molecules and detectable by reflectance, Raman, or ultraviolet-induced fluorescence spectroscopies. However, exposed interior surfaces show unique endolithic signatures detectable by each spectroscopic technique. This indicates that cryptoendolithic communities can be detected via spectroscopy-based techniques, provided they are either partially or fully exposed and enough photon–target interactions occur to enable detection.

Keywords

biosignaturecryptoendolithgypsumMarsRamanspectroscopy
Type
Research Article
Information
International Journal of Astrobiology , Volume 13 , Issue 4 , October 2014 , pp. 366 - 377
Copyright
Copyright © Cambridge University Press 2014 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allwood, A.C., Burch, I.W., Rouchy, J.M. & Coleman, M. (2013). Morphological biosignatures in gypsum: diverse formation processes of messinian (~6.0 Ma) gypsum stromatolites. Astrobiology 13(9), 870–886.CrossRefGoogle ScholarPubMed
Bannatyne, B.B. (1959). Gypsum-anhydrite deposits of Manitoba. Manitoba Mines Branch 258, 46.Google Scholar
Bannatyne, B.B. & McCabe, H.R. (1984). Manitoba crater revealed. GEOS 13, 10–13.Google Scholar
Barbieri, R. & Stivaletta, N. (2011). Continental evaporites and the search for evidence of life on Mars. Geol. J. 46, 513–524.Google Scholar
Battler, M.M., Osinski, G.R. & Banerjee, N.R. (2013). Mineralogy of saline perennial cold spring on Axel Heiberg Island, Nunavut, Canada and implications for spring deposits on Mars. Icarus 224, 364–381.CrossRefGoogle Scholar
Bell, J.F. et al. (2003). Mars exploration rover athena panoramic camera (Pancam) investigation. J. Geophys. Res. 108, 8063. DOI: 10.1029/2003JE002070, E12.Google Scholar
Berenblut, B.J., Dawson, P. & Wilkinson, G.R. (1973). A comparison of the Raman spectra of anhydrite (CaSO4) and gypsum (CaSO4.2H2O). Spectrochim. Acta 29A, 29–36.CrossRefGoogle Scholar
Boison, G., Mergel, A., Jolkver, H. & Bothe, H. (2004). Bacterial life and dinitrogen fixation at a gypsum rock. Appl. Environ. Microbiol. 70(12), 7070–7077.Google Scholar
Boomer, S.M., Lodge, D.P., Dutton, B.E. & Pierson, B. (2002). Molecular characterization of novel red green nonsulfur bacteria from five distinct hot spring communities in Yellowstone National Park. Appl. Environ. Microbiol. 68(1), 346–355.Google Scholar
Botero, L.M., Brown, K.B., Brumefielf, S., Burr, M., Castenholz, R.W., Young, M. & McDermott, T.R. (2004). Thermobaculum terrenum gen. nov., sp, nov.: a non-phototrophic gram-positive thermophile representing an environmental clone group related to the Chloroflexi (green non-sulfur bacteria) and Thermomicrobia. Arch. Microbiol. 181, 269–277.Google Scholar
Bryant, D.A. & Frigaard, N.U. (2006). Prokaryotic photosynthesis and phototrophy illuminated. Trends Microbial 14(11), 488–496.CrossRefGoogle ScholarPubMed
Bryant, D.A. et al. (2007). Candidatus Chloracidobacterium thermophilum: an aerobic phototrophic acidobacterium. Science 317, 523–526.CrossRefGoogle ScholarPubMed
Cady, L.S., Farmer, J.D., Grotzinger, J.P., Schopf, J.W. & Steele, A. (2003). Morphological biosignatures and the search for life on Mars. Astrobiology 3(2), 351–368.CrossRefGoogle ScholarPubMed
Campanella, L., Cubadda, F., Sammartino, M.P. & Saoncella, A. (2000). An algal biosensor for the monitoring of water toxicity in estuarine environments. Water Res. 35, 69–76.CrossRefGoogle Scholar
Canfield, D.E., Sørensen, K.B. & Oren, A. (2004). Biogeochemistry of a gypsum-encrusted microbial ecosystem. Geobiology 2, 133–150.CrossRefGoogle Scholar
Carter, J., Poulet, F., Bibring, J.P., Mangold, N. & Murchie, S. (2013). Hyfrous minerals on Mars as seen by the CRISM and OMEGA imagine spectrometers: updated global view. J. Geophys. Res., Planets 118, 1–28.Google Scholar
Choi, D.W. et al. (2010). Spectral and thermodynamic properties of methanobactin from γ- proteobacterial methan oxidizing bacteria: a case for copper competition on a molecular level. J. Inorg. Biochem. 104, 1240–1247.Google Scholar
Cloutis, E.A. et al. (2006). Detection and discrimination of sulphate minerals using reflectance spectroscopy. Icarus 184, 121–157.CrossRefGoogle Scholar
Cloutis, E.A., Craig, M.A., Mustard, J.F., Kruzelecky, R.V., Jamroz, W.R., Scott, A., Bish, D.L., Poulet, F., Bebring, J.P. & King, P.L. (2007). Stability of hydrated minerals on Mars. Geophys. Res. Lett. 34, L20202.Google Scholar
Cloutis, E.A., Craig, M.A., Kruzelecky, R.V., Jamroz, W.R., Scott, A., Hawthorne, F.C. & Mertzman, S.A. (2008). Spectral reflectance properties of minerals exposed to simulated Mars surface conditions. Icarus 195, 140–168.CrossRefGoogle Scholar
Cloutis, E.A., Berard, G., Mann, P. & Stromberg, J. (2011). The Gypsumville – Lake St. Martin impact structure: Shocked carbonates, intracrater evaporates and cryptoendoliths. In Analogue sites for Mars Special Meeting, the 42nd Annual Lunar and Planetary Science Conference, The Woodlands, Texas. Abstract #6009.Google Scholar
Cockell, C.S., Lee, P., Osinski, G., Horneck, G. & Broady, P. (2002). Impact-induced microbial endolithic habitats. Meteor. Planet. Sci. 37, 1287–1298.Google Scholar
Cockell, C.S., Scheurger, A.C., Billi, D., Friedmann, E.I. & Panitz, C. (2005). Effects of a simulated Martian UV flux on the cyanobacterium, Chroococcidiopsis sp. 029. Astrobiology 5(2), 127–140.Google Scholar
Cockell, C.S., Osinski, G.R., Banerjee, N.R., Howard, K.T., Gilmour, I. & Watson, J.S. (2010). The microbe-mineral environment and gypsum neogenesis in a weathered polar evaporite. Geobiology 8, 293–308.CrossRefGoogle Scholar
Cogdell, R.J., Howard, T.D., Bittl, R., Schlodder, E., Geisenheimer, I. & Lubitz, W. (2000). How carotenoids protect bacterial photosynthesis. Phil. Trans. R. Soc. Lond. B Biol. Sci. 355(1402), 1345–1349.Google Scholar
Costello, E.K. & Schmidt, S.K. (2006). Microbial diversity in alpine tundra wet meadow soil: novel Chloroflexi from a cold, water-saturated environment. Environ. Microbiol. 8, 1471–86.Google Scholar
Dartnell, L.R. et al. (2012). Experimental determination of photostability and fluorescence-based detection of PAHs on the Martian surface. Meteor. Planet. Sci. 47, 806–819.CrossRefGoogle Scholar
Dartnell, L.R. & Patel, M.R. (2013). Degradation of microbial fluorescence biosignatures by solar ultraviolet radiation on Mars. Int. J. Astrobiol. 13, 1–12.Google Scholar
Davis, W.L. & McKay, C.P. (1996). Origins of life: a comparison of theories and application to Mars. Orig. Life Evol. Biosph. 26, 61–73.CrossRefGoogle ScholarPubMed
Delaye, L. & Lazcano, A. (2005). Prebiological evolution and the physics of the origin of life. Phys. Life Rev. 2, 47–64.CrossRefGoogle ScholarPubMed
de Vera, J.P., Duali, S., Kereszturi, A., Konca, L., Lorek, A., Mohlmann, D., Marschall, M. & Pocs, T. (2013). Results on the survival of cryptobiotic cyanobacteria samples after exposure to Mars-like environmental conditions. Int. J. Astrobiol. 13, 35–44.CrossRefGoogle Scholar
Dong, H., Rech, J.A., Jiang, H., Sun, H. & Buck, B.J. (2007). Endolithic cyanobacteria in soil gypsum: occurrences in Atacama (Chile), Mojave (United States), and Al-Jafr Basin (Jordan) deserts. J. Geophys. Res. 112(G2), G02030.Google Scholar
Douglas, S., Abbey, W., Mieke, R., Conrad, P. & Kanik, I. (2008). Textural and mineralogical biosignatures in an unusual microbialite from Death Valley, California. Icarus 193, 620–636.CrossRefGoogle Scholar
Edwards, H.G.M. (2010). Raman spectroscopic approach to analytical astrobiology: the detection of key geological and biomolecular markers in the search for life. Phil. Trans. R. Soc. A 368, 3059–3065.CrossRefGoogle ScholarPubMed
Edwards, H.G.M., Newton, E.M., Wynn-Williams, D.D., Dickensheets, D., Schoen, C. & Crowder, C. (2003). Laser wavelength selection for Raman spectroscopy of microbial pigments in situ in Antarctic desert ecosystem analogues of former habitats on Mars. Int. J. Astrobiol. 1(4), 333–348.CrossRefGoogle Scholar
Edwards, H.G.M., Jorge Villar, S.E., Parnell, J., Cockell, C. & Lee, P. (2005a). Raman spectroscopic analysis of cyanobacterial gypsum halotrophs and relevance for sulfate deposits on Mars. Analyst 130, 917–923.CrossRefGoogle ScholarPubMed
Edwards, H.G.M., Moody, C.D., Jorge Villar, S.E. & Wynn-Williams, D.D. (2005b). Raman spectroscopic detection of key biomarkers of cyanobacteria and lichen symbiosis in extreme Antarctic habitats: evaluation for Mars lander missions. Icarus 174, 560–571.CrossRefGoogle Scholar
Ellery, A., Kolb, C., Lammer, H., Parnell, J., Edwards, H., Richter, L., Patel, M., Romstedt, J., Dickensheets, D., Steele, A. & Cockell, C. (2003). Astrobiological instrumentation for Mars – the only way is down. Int. J. Astrobiol. 1(4), 365–380.CrossRefGoogle Scholar
Farmer, J.D. & Des Marias, D.J. (1999). Exploring for a record of ancient Martian life. J. Geophys. Res. 104(E11), 26977–26995.CrossRefGoogle ScholarPubMed
Filella, I. & Penuelas, J. (1994). The red edge and shape as indicators of plant chlorophyll content, biomass and hydric state. Int. J. Remote Sens. 15(7), 1459–1470.CrossRefGoogle Scholar
Friedmann, E.I. (1982). Endolithic microorganisms in the Antarctic cold desert. Science 215, 1045–1053.CrossRefGoogle ScholarPubMed
Gall, A., Yurkov, V., Vermeglio, A. & Robert, B. (1999). Certain species of the Proteobacteria possess unusual bacteriochlorophyll a environments in their light-harvesting proteins. Biospectroscopy 5, 338–345.3.0.CO;2-D>CrossRefGoogle ScholarPubMed
Garbary, D.J., Van Thielen, N. & Miller, A. (1996). Endolithic algae from gypsum in Nova Scotia. J. Phycol. 32(Suppl.), 17.Google Scholar
Garrity, G.M. & Holt, J.G. (2001). Phylum BVI. Chloroflexi phy. nov. In Bergey's Manual of Systematic Bacteriology, ed. Boone, D.R., Castenholz, R.W. & Garrity, R.W., pp. 427–446. Springer, New York, NY, USA.Google Scholar
Gendrin, A., Mangold, N., Bibring, J-P., Langevin, Y., Gondet, B., Poulet, F., Bonello, G., Quantin, K., Mustard, J., Arvidson, R. & LeMouelic, S. (2005). Sulfates in Martian layered terrains: the OMEGA/Mars express view. Science 307, 1587–1589.CrossRefGoogle ScholarPubMed
Gomez, F.M. et al. (2012). Habitability: where to look for life? Halophilic habitats: earth analogs to study Mars habitability. Planet. Space Sci. 68, 48–55.CrossRefGoogle Scholar
Grotzinger, J.P. et al. (2013). A habitable fluvio-lacustrine environment at Yellowknife Bay, Gale Crater, Mars. Science 10(1126), 1–17.Google Scholar
Hughes, K.A. & Lawley, B. (2003). A novel Antarctic microbial endolithic community within gypsum crusts. Environ. Microbiol. 5(7), 555–565.Google Scholar
Holm, N.G. & Andersson, E. (2005). Hydrothermal simulation experiments as a tool for studies of the origin of life on earth and other terrestrial planets: a review. Astrobiology 5, 444–460.CrossRefGoogle ScholarPubMed
Kelly, C.A., Poole, J.A., Tazaz, A.M., Chanton, J.P. & Bebout, B.M. (2012). Substrate limitation for methanogenesis in hypersaline environments. Astrobiology 12(2), 89–97.Google Scholar
Kleinegris, D.M.M., van Es, M.A., Janssen, M., Brandenburg, W.A. & Wijffels, R.H. (2010) Carotenoid fluorescence in Dunaliella salina . J. Appl. Phycol. 22(5), 645–649.Google Scholar
Kraus, G.H. & Weis, E. (1991) Chlorophyll fluorescence and photosynthesis: the basics. Annu. Rev. Plant Physiol. Plant Mol. Biol. 42, 313–349.Google Scholar
Krishnamurthy, N. & Soots, V. (1971). Raman spectrum of gypsum. Can. J Phys. 49, 885–896.CrossRefGoogle Scholar
Kubo, Y., Ikeda, T., Yang, S.Y. & Tsuboi, M. (2000). Orientation of carotenoid molecules in the eyespot of algae: in situ polarized resonance Raman spectroscopy. Appl. Spectrosc. 54, 1114–1119.CrossRefGoogle Scholar
Langevin, Y., Poulet, F., Bibring, J-P. & Gondet, B. (2005). Sulfates in the north polar region of Mars detected by OMEGA/Mars express. Science 307, 1584–1586.Google Scholar
Leybourne, M.I., Denison, R.E., Cousens, B.L., Bezys, R.K., Gregoire, D.C., Boyle, D.R. & Dobrzanski, E. (2007). Geochemistry, geology, and isotopic (Sr, S, and B) composition of evaporites in the Lake St. Martin impact structure: new constraints on the age of melt rock formation. Geochem. Geophys. Geosyst. 8, 1–22. DOI: 10.1029/2006GC001481.Google Scholar
Lim, D. (2002). Microbiology, 3rd edn. Kendall/Hunt Publishing Company, Dubuque, Iowa.Google Scholar
Lopez-Reyes, G. et al. (2013). Analysis of the scientific capabilities of the ExoMars Raman Laser Spectrometer instrument. Eur. J. Mineral. 25, 721–733.Google Scholar
Lutz, M. (1974). Resonance Raman spectra of chlorophyll in solution. J. Raman Spectrosc. 2, 497–516.CrossRefGoogle Scholar
Marshall, C.P. & Marshall, A.O. (2010). The potential of Raman spectroscopy for the analysis of diagenetically transformed carotenoids. Philos. Trans. R. Soc. A: Math. Phys. Eng. Sci. 368(1922), 3137–3144.Google Scholar
Martinez-Frias, J., Amaral, G. & Vázquez, L. (2006). Astrobiological significance of minerals on Mars surface environment. Rev. Environ. Sci. Biotechnol. 5, 219–231.CrossRefGoogle Scholar
Massé, M., Bourgeois, O., Mouélic, S., Verpoorter, C., Le Deit, L. & Bibring, J.P. (2010). Martian polar and circum-polar sulfate-bearing deposits: sublimation tills derived from the north polar cap. Icarus 209, 434–451.Google Scholar
McCabe, H.R. & Bannatyne, B.B. (1970). Lake St. Martin crypto-explosion crater and geology of surrounding area. Geolog. Surv. Manitoba 3, 70–79.Google Scholar
McKay, C.P. (1997). The search for life on Mars. Orig. Life Evol. Biosph. 27(1–3), 263–289.Google Scholar
Merzlyak, M.N., Gitelson, A.A., Chiykunova, O.B., Solovchenko, A.E. & Pogosyan, S.I. (2003). Application of reflectance spectroscopy for analysis of higher plant pigments. Russ. J. Plant Physiol. 50(5), 704–710.CrossRefGoogle Scholar
Milliken, R.E., Grotzinger, J.P. & Thomson, B.J. (2010). Paleoclimate of Mars as captured by the stratigraphic record in Gale Crater. Geophys R. Lett. 37, L04201.Google Scholar
Morris, R.V., Lauer, H.V., Lawson, C.A., Gibson, E.K., Nace, G.A. & Stewart, C. (1985). Spectral and other physicochemical properties of sub-micron powders of hematite, maghemite, magnetite, goethite, and lepidocrocite. J. Geo. Phys. Res. 90(B4), 3126–3144.CrossRefGoogle Scholar
Murchie, S.L. et al. (2009). A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars reconnaissance orbiter. J. Geo. Phys. Res. 114, E00D06.Google Scholar
Panieri, G., Lugli, S., Manzi, V., Palinska, K.A. & Roveri, M. (2008). Microbial communities in Messinian evaporite deposits of the Vena del Gesso (northern Apennines, Italy). Stratigraphy 5, 343–352.Google Scholar
Panieri, G., Lugli, S., Manzi, V., Schreiber, B.C., Palinska, K.A. & Roveri, M. (2010). Ribosomal RNA gene fragments from fossilized cyanobacteria identified in primary gypsum from the late Miocene, Italy. Geobiology 8, 101–111.Google Scholar
Preston, L.J. & Dartnell, L.R. (2014). Planetary habitability: lessons learned from terrestrial analogues. Int. J. Astrobiol. 13(01), 81–98.Google Scholar
Poch, O., Noblet, A., Stalport, F., Correia, , Grand, N., Szopa, C. & Coll, P. (2013). Chemical evolution of organic molecules under Mars-like UV radiation conditions simulated in the laboratory with the MOMIE setup. Planet. Space Sci. 85, 188–197.Google Scholar
Quesada, A., Vincent, W.F. & Lean, D.R.S. (1999). Community and pigment structure of Arctic cyanobacterial assemblages: the occurrence and distribution of UV-absorbing compounds. FEMS Microb. Ecol. 28, 315–323.Google Scholar
Raulin, F. & McKay, C.P. (2002). The search for extraterrestrial life and prebiotic chemistry. Planet. Space Sci. 50, 655–655.CrossRefGoogle Scholar
Richardson, L.L. (1995). Remote sensing of algal bloom dynamics. BioScience 46(7), 492–501.Google Scholar
Robert, B., Frank, H.A., Young, A.J., Britton, G. & Cogdell, R.J. (1999). The Photochemistry of Carotenoids, pp. 189. Kluwer Academic Publishers, Dordrecht, The Netherlands.Google Scholar
Schloss, P.D., Westcott, S.L., Ryabin, T., Hall, J.R., Hartmann, M., Hollister, E.B., Lesniewski, R.A., Oakley, B.B., Parks, D.H., Robinson, C.J. et al. (2009). Introducing mothur: open-source, platform-independent, community-supported software for describing and comparing microbial communities. Appl. Environ. Microbiol. 75(23), 7537–7541.Google Scholar
Schloss, P.D., Gevers, D. & Westcott, S.L. (2011). Reducing the effects of PCR amplification and sequencing artifacts on 16S rRNA-based studies. PLoS ONE 6(12), e27310–e27310.Google Scholar
Schmieder, M., Jourdan, F., Tohver, E., Mayers, C., Frew, A. & Cloutis, E. (2013). The age of the lake Saint Martin impact structure (Manitoba, Canada). 44th Lunar and Planetary Science Conference (abstract).Google Scholar
Schopf, J.W., Farmer, J.D., Foster, I.S., Kudryavtsev, A.B., Gallardo, V.A. & Espinoza, C. (2012). Gypsum-permineralized microfossils and their relevence to the search for life on Mars. Astrobiology 12(7), 619–633.Google Scholar
Seager, S., Turner, E.L., Schafer, J. & Ford, E.B. (2005). Vegetation's Red Edge: a possible spectroscopic biosignature for extraterrestrial life. Astrobiology 5(3), 372–389.Google Scholar
Seckback, J. (Ed). (1999). Enigmatic Microorganisms and Life in Extreme Environments. Kluwer Academic Publishers, Dordrecht, The Netherlands.Google Scholar
Sefton-Nash, E., Catling, D.C., Wood, S.E., Grindrod, P.M. & Teanby, N.A. (2012). Topographic, spectral, and thermal inertia analysis of interior layered deposits in Iani Chaos, Mars. Icarus 221, 20–42.Google Scholar
Sherman, D.M. & Waite, T.D. (1985). Electronic spectra of Fe3+ oxides and oxide hydroxides in the near IR to UV. Am. Mineral. 70, 1262–1269.Google Scholar
Shibata, Y., Saga, Y., Tamiaki, H. & Itoh, S. (2007). Polarized fluorescence of aggregated bacteriochlorophyll c and baseplate bacteriochlorophyll a in single chlorosomes isolated from Chloroflexus aurantiacus . Am. Chem. Soc. 46, 7062–7068.Google Scholar
Sigler, W.V., Bachofen, R. & Zeyer, J. (2003). Molecular characterization of endolithic cyanobacteria inhabiting exposed dolomite in central Switzerland. Environ. Microbiol. 5(7), 618–627.Google Scholar
Simoneit, B.R.T. (2004). Prebiotic organic synthesis under hydrothermal conditions: an overview. Adv. Space Res. 33, 88–94.Google Scholar
Squier, A.H., Hodgson, D.A. & Keely, B.J. (2004). A critical assessment of the analysis and distributions of scytonemin and related UV screening pigments in sediments. Org. Geochem. 35, 1221–1228.Google Scholar
Squyres, S.W. et al. (2012). Ancient impact and aqueous processes at Endeavour Crater, Mars. Science 336, 570–576.Google Scholar
Stivaletta, N., López-García, P., Boihem, L. & Barbieri, R. (2010). Biomarkers of endolithic communities within gypsum crusts (Southern Tunisia). Geomicrobiol. J. 27, 101–110.Google Scholar
Stoker, C.R. & Bullock, M.A. (1997). Organic degradation under simulated Martian conditions. J. Geo. Phys. Res. 102(E5), 10881–10888.Google Scholar
Stromberg, J.M., Applin, D.M., Cloutis, E.A., Rice, M., Berard, G. & Mann, P. (2014). The persistence of a chlorophyll spectral bio signature from Martian evaporite and spring analogues under Mars-like conditions. Int. J. Astrobiol. 13(3), 203–223.Google Scholar
Strommen, D.P. & Nakamoto, K. (1977). Resonance Raman spectroscopy. J. Chem. Educ. 54, 474.Google Scholar
Summons, R.E., Amend, J.P., Bish, D., Buick, R., Cody, G.D., Des Marais, D.J., Dromart, G., Eigenbrode, J.L., Knoll, A.H. & Sumner, D.Y. (2011). Preservation of Martian organic and environmental records: final repost of the Mars biosignature working group. Astrobiology 22(2), 157–181.Google Scholar
Suo, Z., Avci, R., Schweitzer, M.H. & Deliorman, M. (2007). Porphyrin as an ideal biomarker in the search for extraterrestrial life. Astrobiology 7(4), 605–615.Google Scholar
van Amerongen, H., Vasemel, H. & van Grondelle, R. (1988). Linear dichroism of chlorosomes from Chloroflexus aurantiacus in compressed gels and electric fields. Biophys. J. 54, 65–76.Google Scholar
van Amerongen, H., van Haeringen, B., van Gurp, M. & van Grondelle, R. (1991). Polarized fluorescence measurements on ordered photosynthetic antenna complexes. Biophys. J. 59, 992–1001.CrossRefGoogle ScholarPubMed
Vasmel, H., van Dorssen, R.J., Vasmel, H. & Amesz, J. (1986) Pigment organization and energy transfer in the green photosynthetic bacterium Chloroflexus aurantiacus . Photosynth. Res. 9, 33–45.Google Scholar
Villar, S.E., Edwards, H.G.M. & Benning, L.G. (2006). Raman spectroscopic and scanning electron microscopic analysis of a novel biological colonization of volcanic rocks. Icarus 184, 158–169.Google Scholar
Wardlaw, N.C., Stauffer, M.R. & Hoque, M. (1969). Striations, giants grooves, and superposed drag folds, Interlake area, Manitoba. Can. J. Earth Sci. 6(4), 577–593.Google Scholar
Wierzchos, J., Ascaso, C. & McKay, C.P. (2006). Endolithic cyanobacteria in halite rocks from the hyper arid core of the Atacama Desert. Astrobiology 6(3), 415–422.Google Scholar
Wierzchos, J., Mara, B.C.A., De Los Rios, A., Davila, A.F., Sanchez-Almazo, I.M., Artieda, O., Wierzchos, K., Gomez-Silva, B., McKay, C.P. & Ascaso, C. (2011). Microbial colonization of Ca-sulfate crusts in the hyper arid core of the Atacama Desert: implications for the search for life on Mars. Geobiology 9, 44–60.Google Scholar
Wray, J.J. et al. (2010). Identification of the Ca-sulfate bassanite in Mawrth Vallis, Mars. Icarus 209, 416–421.Google Scholar
Wray, J.J. et al. (2011). Columbus crater and other possible groundwater-fed paleolakes of Terra Sirenum, Mars. J. Geophys. Res. 116, E01001.Google Scholar
Wynn-Williams, D.D., Edwards, H.G.M. & Garcia-Pichel, F. (1999). Functional biomolecules of Antarctic stromatolitic and endolithic cyanobacterial communities. Eur. J. Phycol. 34(4), 381–391.Google Scholar
Yamada, T., Sekiguchi, Y., Hanada, S., Imachi, H., Ohashi, A., Harada, H. & Kamagata, Y. (2006). Anaerolinea thermolimosa sp. nov., Levilinea saccharolytica gen. nov., sp. nov. and Leptolinea tardivitalis gen. nov., sp. nov., novel filamentous anaerobes, and description of the new classes Anaerolineae classis nov. and Caldilineae classis nov. in the bacterial phylum Chloroflexi . Int. J. Syst. Evol. Microbiol. 56(6), 1331–1340.Google Scholar
Ziolkowski, L.A., Mykytczuk, N.C.S., Omelon, C.R., Johnson, H., Whyte, L.G. & Slater, G.F. (2013). Arctic gypsum endoliths: a biogeochemical characterization of a viable and active microbial community. Biogeosciences 10(11), 7661–7675.Google Scholar