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Wide distribution of autochthonous branched glycerol dialkyl glycerol tetraethers (bGDGTs) in U.S. Great Basin hot springs

Hedlund, Brian P. and Paraiso, Julienne J. and Williams, Amanda J. and Huang, Qiuyuan and Wei, Yuli and Dijkstra, Paul and Hungate, Bruce A. and Dong, Hailiang and Zhang, Chuanlun (2013) Wide distribution of autochthonous branched glycerol dialkyl glycerol tetraethers (bGDGTs) in U.S. Great Basin hot springs. Terrestrial Microbiology, 4 (222). pp. 1-10. ISSN 1664-302X

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Publisher’s or external URL: http://dx.doi.org/10.3389/fmicb.2013.00222

Abstract

Branched glycerol dialkyl glycerol tetraethers (bGDGTs) are membrane-spanning lipids that likely stabilize membranes of some bacteria. Although bGDGTs have been reported previously in certain geothermal environments, it has been suggested that they may derive from surrounding soils since bGDGTs are known to be produced by soil bacteria. To test the hypothesis that bGDGTs can be produced by thermophiles in geothermal environments, we examined the distribution and abundance of bGDGTs, along with extensive geochemical data, in 40 sediment and mat samples collected from geothermal systems in the U.S. Great Basin (temperature: 31–95°C; pH: 6.8–10.7). bGDGTs were found in 38 out of 40 samples at concentrations up to 824 ng/g sample dry mass and comprised up to 99.5% of total GDGTs (branched plus isoprenoidal). The wide distribution of bGDGTs in hot springs, strong correlation between core and polar lipid abundances, distinctness of bGDGT profiles compared to nearby soils, and higher concentration of bGDGTs in hot springs compared to nearby soils provided evidence of in situ production, particularly for the minimally methylated bGDGTs I, Ib, and Ic. Polar bGDGTs were found almost exclusively in samples ≤70°C and the absolute abundance of polar bGDGTs correlated negatively with properties of chemically reduced, high temperature spring sources (temperature, H2S/HS−) and positively with properties of oxygenated, low temperature sites (O2, NO−3). Two-way cluster analysis and nonmetric multidimensional scaling based on relative abundance of polar bGDGTs supported these relationships and showed a negative relationship between the degree of methylation and temperature, suggesting a higher abundance for minimally methylated bGDGTs at high temperature. This study presents evidence of the widespread production of bGDGTs in mats and sediments of natural geothermal springs in the U.S. Great Basin, especially in oxygenated, low-temperature sites (≤70°C).

Item Type: Article
Publisher’s Statement: This Document is Protected by copyright and was first published by Frontiers. All rights reserved. It is reproduced with permission
ID number or DOI: 10.3389/fmicb.2013.00222
Keywords: geothermal springs, membrane-spanning lipids, bGDGTs, thermophiles, Great Basin, lipids
Subjects: Q Science > QH Natural history > QH301 Biology
Department/Unit: College of Engineering, Forestry, and Natural Science > Biological Sciences
Research Centers > Center for Ecosystem Science and Society
Date Deposited: 28 Mar 2016 21:44
URI: http://openknowledge.nau.edu/id/eprint/1878

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