Next Article in Journal
Crosslinked Hyaluronic Acid Gels for the Prevention of Intrauterine Adhesions after a Hysteroscopic Myomectomy in Women with Submucosal Myomas: A Prospective, Randomized, Controlled Trial
Previous Article in Journal
Identification and Validation of Aerobic Adaptation QTLs in Upland Rice

Biosignatures Associated with Freshwater Microbialites

Department of Plant Pathology, Washington State University, Pullman, WA 99163, USA
RAW Molecular Systems (RMS) LLC, Spokane, WA 99218, USA
Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW 2052, Australia
School of Geography and Earth Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada
School of Earth and Environmental Sciences, University of Queensland, QLD 4072, Australia
NASA Ames Research Center, Moffett Field, CA 94035, USA
Author to whom correspondence should be addressed.
These authors equally contributed.
Life 2020, 10(5), 66;
Received: 31 March 2020 / Revised: 11 May 2020 / Accepted: 11 May 2020 / Published: 15 May 2020
Freshwater microbialites (i.e., lithifying microbial mats) are quite rare in northern latitudes of the North American continent, with two lakes (Pavilion and Kelly Lakes) of southeastern BC containing a morphological variety of such structures. We investigated Kelly Lake microbialites using carbon isotope systematics, phospholipid fatty acids (PLFAs) and quantitative PCR to obtain biosignatures associated with microbial metabolism. δ13CDIC values (mean δ13CDIC −4.9 ± 1.1‰, n = 8) were not in isotopic equilibrium with the atmosphere; however, they do indicate 13C-depleted inorganic carbon into Kelly Lake. The values of carbonates on microbialite surfaces (δ13C) fell within the range predicted for equilibrium precipitation from ambient lake water δ13CDIC (−2.2 to −5.3‰). Deep microbialites (26 m) had an enriched δ13Ccarb value of −0.3 ± 0.5‰, which is a signature of photoautotrophy. The deeper microbialites (>20 m) had higher biomass estimates (via PLFAs), and a greater relative abundance of cyanobacteria (measured by 16S copies via qPCR). The majority of PLFAs constituted monounsaturated and saturated PLFAs, which is consistent with gram-negative bacteria, including cyanobacteria. The central PLFA δ13C values were highly depleted (−9.3 to −15.7‰) relative to δ13C values of bulk organic matter, suggesting a predominance of photoautotrophy. A heterotrophic signature was also detected via the depleted iso- and anteiso-15:0 lipids (−3.2 to −5.2‰). Based on our carbonate isotopic biosignatures, PLFA, and qPCR measurements, photoautotrophy is enriched in the microbialites of Kelly Lake. This photoautotrophy enrichment is consistent with the microbialites of neighboring Pavilion Lake. This indication of photoautotrophy within Kelly Lake at its deepest depths raises new insights into the limits of measurable carbonate isotopic biosignatures under light and nutrient limitations. View Full-Text
Keywords: Kelly Lake; Pavilion Lake; microbialites; biosignatures Kelly Lake; Pavilion Lake; microbialites; biosignatures
Show Figures

Figure 1

MDPI and ACS Style

White, R.A., III; Soles, S.A.; Brady, A.L.; Southam, G.; Lim, D.S.S.; Slater, G.F. Biosignatures Associated with Freshwater Microbialites. Life 2020, 10, 66.

AMA Style

White RA III, Soles SA, Brady AL, Southam G, Lim DSS, Slater GF. Biosignatures Associated with Freshwater Microbialites. Life. 2020; 10(5):66.

Chicago/Turabian Style

White, Richard Allen, III, Sarah A. Soles, Allyson L. Brady, Gordon Southam, Darlene S.S. Lim, and Greg F. Slater. 2020. "Biosignatures Associated with Freshwater Microbialites" Life 10, no. 5: 66.

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop