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Title: Distribution and abundance of tetraether lipid cyclization genes in terrestrial hot springs reflect pH

Many Archaea produce membrane‐spanning lipids that enable life in extreme environments. These isoprenoid glycerol dibiphytanyl glycerol tetraethers (GDGTs) may contain up to eight cyclopentyl and one cyclohexyl ring, where higher degrees of cyclization are associated with more acidic, hotter or energy‐limited conditions. Recently, the genes encoding GDGT ring synthases,grsAB, were identified in two Sulfolobaceae; however, the distribution and abundance ofgrshomologs across environments inhabited by these and related organisms remain a mystery. To address this, we examined the distribution ofgrshomologs in relation to environmental temperature and pH, from thermal springs across Earth, where sequences derive from metagenomes, metatranscriptomes, single‐cell and cultivar genomes. The abundance ofgrshomologs shows a strong negative correlation to pH, but a weak positive correlation to temperature. Archaeal genomes and metagenome‐assembled genomes (MAGs) that carry two or moregrscopies are more abundant in low pH springs. We also findgrsin 12 archaeal classes, with the most representatives in Thermoproteia, followed by MAGs of the uncultured Korarchaeia, Bathyarchaeia and Hadarchaeia, while several Nitrososphaeria encodes >3 copies. Our findings highlight the key role ofgrs‐catalysed lipid cyclization in archaeal diversification across hot and acidic environments.

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Journal Name:
Environmental Microbiology
Page Range / eLocation ID:
p. 1644-1658
Medium: X
Sponsoring Org:
National Science Foundation
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