Multiple environmental parameters impact lipid cyclization in Sulfolobus acidocaldarius

Area of Science:

• Microbiology
• Biochemistry
• Geochemistry

Background:

• Archaeal lipid membrane composition is crucial for homeostasis.
• Glycerol dibiphytanyl glycerol tetraether (GDGT) ring number historically linked to temperature.
• Emerging evidence suggests pH and energy availability influence GDGT cyclization.

Purpose of the Study:

• To investigate the impact of multiple environmental variables on GDGT cyclization in Sulfolobus acidocaldarius.
• To understand the relationship between GDGT cyclization and cellular growth parameters.
• To determine if GDGT cyclization reflects a universal cellular response to energy availability.

Main Methods:

• Cultivation of Sulfolobus acidocaldarius DSM639 under varied temperature, pH, oxygen flux, and agitation.
• Quantification of growth rate, biomass yield, and core lipid compositions.
• Analysis of the degree of glycerol dibiphytanyl glycerol tetraether (GDGT) cyclization.

Main Results:

• GDGT cyclization degree correlated with growth rate across most tested conditions.
• The study identified key individual parameters influencing GDGT cyclization.
• Findings suggest GDGT cyclization is a sensitive indicator of cellular energy status.

Conclusions:

• GDGT cyclization in archaeal lipids appears to be a universal response to cellular energy availability.
• This response is observed in both thermoacidophiles and mesoneutrophilic Thaumarchaea.
• Further multi-factor experiments are needed to refine the understanding of homeostatic membrane responses.