Impacts of temperature and pH on the distribution of archaeal lipids in Yunnan hot springs, China

Weiyan Wu,Chuanlun L Zhang,Hailiang Dong,Wenjun Li,Huanye Wang,Liu He

doi:10.3389/fmicb.2013.00312

Abstract

In culture experiments and many low temperature environments, the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) commonly shows a strong correlation with temperature; however, this is often not the case in hot springs. We studied 26 hot springs in Yunnan, China, in order to determine whether temperature or other factors control the distribution of GDGTs in these environments. The hot springs ranged in temperature from 39.0 to 94.0°C, and in pH from 2.35 to 9.11. Water chemistry including nitrogen-, sulfur-, and iron species was also determined. Lipids from the samples were analyzed using liquid chromatography–mass spectrometry (LC–MS). Distributions of GDGTs in these hot springs were examined using cluster analysis, which resulted in two major groups. Group 1 was characterized by the lack of dominance of any individual GDGTs, while Group 2 was defined by the dominance of GDGT-0 or thaumarchaeol. Temperature was the main control on GDGT distribution in Group 1, whereas pH played an important role in the distribution of GDGTs in Group 2. However, no correlations were found between the distribution of GDGTs and any of the nitrogen-, sulfur-, or iron species. Results of this study indicate the dominance of temperature or pH control on archaeal lipid distribution, which can be better evaluated in the context of lipid classification.

Highlights

Isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) as essential membrane lipids of Archaea widely occur in natural environments (Schouten et al, 2013 and references therein)
Results of this study indicate the dominance of temperature or pH control on archaeal lipid distribution, which can be better evaluated in the context of lipid classification
Soils surrounding Yunnan hot springs were not sampled in this study, they were collected in later field trips (Xie et al, unpublished), and showed an obvious difference in GDGT distribution from geothermal springs (Figure A2 in Appendix), suggesting that GDGTs in the hot springs are dominated by those

Summary

Introduction

Isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) as essential membrane lipids of Archaea widely occur in natural environments (Schouten et al, 2013 and references therein). They can contain up to eight cyclopentyl rings (Trincone et al, 1988; Schouten et al, 2000, 2007). The ratio of thaumarchaeol (Thaum) to GDGT-0 (caldarchaeol) correlated with the relative abundance of Thaumarchaeota to Euryarchaeota in natural settings (Zhang et al, 2006; Turich et al, 2007; Yang et al, 2010), which is consistent with the notion that thaumarchaeol is the biomarker for Thaumarchaeota and GDGT-0 the major component of euryarchaeotal membrane lipids (Schouten et al, 2007)

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Conclusion