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

Brian P. Hedlund, Julienne J. Paraiso, Amanda J. Williams, Qiuyuan Huang, Yuli Wei, Paul Dijkstra, Bruce A. Hungate, Hailiang Dong, Chuanlun L. Zhang

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Branched glycerol dialkyl glycerol tetraethers (bGDGTs) are membrane-spanning lipids that likelystabilize 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 areknown 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 ofbGDGTs 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 ofoxygenated, low temperature sites (O2, NO-3). Two-way cluster analysis and nonmetric multidimensionalscaling 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).

Original languageEnglish (US)
JournalFrontiers in Microbiology
Volume4
Issue numberAUG
DOIs
StatePublished - Jan 1 2013

Keywords

  • Geothermal springs
  • Great basin
  • Lipids
  • Membrane-spanning lipids
  • Thermophiles
  • bGDGTs

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

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