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

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.

A diagnostic GDGT signature for the impact of hydrothermal activity on surface deposits at the Southwest Indian Ridge

“…Similar studies, however, have shown that pH also governs GDGT distributions in thermophilic archaea, with RI increasing as pH decreases in diverse settings (e.g. Boyd et al, 2011Boyd et al, , 2013Wu et al, 2013;Kaur et al, 2015).…”

Carbon Oxidation State in Microbial Polar Lipids Suggests Adaptation to Hot Spring Temperature and Redox Gradients

“…Kaur et al (2015) observed an increase in GDGT ring abundance with temperature between a pH range of 5.5-7.2 in hot springs from the Taupo volcanic zone in New Zealand, though their low pH samples did not. Wu et al (2013) studied GDGTs in Yunnan hot springs, China, and found that ring index increased with temperature in one statistical grouping and increased with acidity in the other.…”

Heat Stress Dictates Microbial Lipid Composition along a Thermal Gradient in Marine Sediments

“…In addition to studies using cultured microorganisms, a limited number of investigations have attempted to reconcile microbial membrane adaptations and lipid distributions in relation to elevated temperatures in natural settings. For instance, variations in the degree of cyclization of glycerol-based tetraether lipids are captured by the Ring-index, which has been applied as a proxy for archaeal membrane lipid adaptation to heat stress in terrestrial hot springs ( Pearson et al, 2004 , 2008 ; Schouten et al, 2007 ; Boyd et al, 2013 ; Paraiso et al, 2013 ; Wu et al, 2013 ; Jia et al, 2014 ). Supported by studies in pure cultures of thermophiles ( De Rosa et al, 1980 ; Uda et al, 2001 ; Shimada et al, 2008 ; Boyd et al, 2011 ), the rationale is that by increasing the number of rings, tetraethers are packed more tightly, decreasing membrane permeability under heat stress ( Gliozzi et al, 1983 ; Gabriel and Chong, 2000 ; Gliozzi et al, 2002 ).…”