Fundamental drivers for endolithic microbial community assemblies in the hyperarid Atacama Desert

Area of Science:

• Astrobiology
• Microbial Ecology
• Geomicrobiology

Background:

• Endolithic microbial communities inhabit rock interiors in hyperarid deserts as a survival strategy.
• Understanding the composition and assembly drivers of these unique ecosystems remains a challenge.

Purpose of the Study:

• To investigate the diversity and community composition of endolithic microorganisms.
• To identify the key drivers shaping endolithic communities across different lithic substrates in the Atacama Desert.

Main Methods:

• Collected endoliths from four distinct rock types (calcite, gypsum, ignimbrite, granite) in the Atacama Desert.
• Employed microscopy, mineralogy, spectroscopy, and high-throughput sequencing for comprehensive analysis.

Main Results:

• Endolithic communities exhibited high substrate specificity.
• Four dominant phyla (Cyanobacteria, Actinobacteria, Chloroflexi, Proteobacteria) were consistently found across substrates.
• Rock architecture (available space, physical structure, water retention) emerged as the primary driver, overriding substrate chemistry and light transmission.

Conclusions:

• Substrate properties, particularly rock architecture, significantly influence endolithic microbial community structure and diversity.
• This finding advances our understanding of life's adaptation strategies at the dry limits of Earth.